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TRANSMITTAL

Florida Institute of Technology Department of Marine and Environmental Systems TO: Dr. Stephen Wood Florida Institute of Technology 150 W. University Blvd. Melbourne, FL 32901 FROM: Team Constant Contact 150 W. University Blvd. Melbourne, FL 32901 RE: Team Constant Contact Final Report DATE SUBMITTED: July 25, 2009

Dr. Stephen Wood; Please review the attached report which was written on our senior design project. Our senior design project was the vertical-axis marine turbine system. We have prepared this proposal to the best of our ability, including references to any text material quoted in this report. Thank you and please contact team leader Joshua Lappen at jlappen@fit.edu if you have any further questions.

Sincerely,

Team Constant Contact

Joshua Lappen _____________________

Travis Schramek _____________________

Michael Smit _____________________

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Team Constant Contact

Joshua Lappen

Team Members:

Travis Schramek Michael Smit

Team Website: http://my.fit.edu/~jlappen/TCC/

Florida Institute of Technology Department of Marine and Environmental Systems

Ocean Engineering Design, 2009 Dr. Stephen Wood, P.E.

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Acknowledgements Team Constant Contact would like to thank:

• Dr. Stephen Wood for his help throughout our project.

• Bill Bailey for his help around the machine shop.

• Jim Tryzbiak for his help around the machine shop.

• Dr. Frank Leslie for his insight into all aspects of renewable energy.

• Dr. Ron Reichard for his help with fluid flows.

• Alan Shaw for his help during the manufacturing of our turbines.

• Vector Works Marine Inc., as well as Janelle Boisvert for their help building the Gorlov Turbine

• Tim Fletcher for his help with the testing of the turbines.

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Table of Contents

1. INTRODUCTION .................................................................................................................................................. 1

1.1 MOTIVATIONS ......................................................................................................................................................... 1 1.2. OBJECTIVES ............................................................................................................................................................ 1 1.3. ORGANIZATION ....................................................................................................................................................... 1

2. BACKGROUND.................................................................................................................................................... 2

2.1 PREVIOUSLY EXISTING SYSTEM .................................................................................................................................... 2 2.1.1 Wind Systems ............................................................................................................................................... 2 2.1.2 Marine Type Systems ................................................................................................................................... 3

3. DESIGN............................................................................................................................................................... 7

3.1. DESIGN EVOLUTION ................................................................................................................................................. 7 3.1.1 Initial Design ................................................................................................................................................ 7 3.1.2 Preliminary Design ....................................................................................................................................... 8

3.2. FINAL DESIGN ......................................................................................................................................................... 9 3.2.1 Turbine Housing ........................................................................................................................................... 9 3.2.2 Bearing ....................................................................................................................................................... 11 3.2.3 Shaft System............................................................................................................................................... 11 3.2.4 Turbine Design ........................................................................................................................................... 11 3.2.5 Pontoon Boat Mounting............................................................................................................................. 14

4. MANUFACTURING AND CONSTRUCTION ......................................................................................................... 15

4.1. TURBINE HOUSING ................................................................................................................................................. 15 4.1.1. Bearing ...................................................................................................................................................... 15

4.2. TURBINES............................................................................................................................................................. 16 4.2.1. Darrieus Turbine ........................................................................................................................................ 16 4.2.2. Gorlov Helical Turbine ............................................................................................................................... 27 4.2.3. Savonius Turbine ....................................................................................................................................... 37

4.3. POWER SYSTEM .................................................................................................................................................... 38 4.3.1. Generator housing .................................................................................................................................... 38 4.3.2 Data Recording System .............................................................................................................................. 38

4.4 PONTOON BOAT ATTACHMENT STRUCTURE ................................................................................................................. 39 4.5 MATERIALS ........................................................................................................................................................... 40

4.5.1 Material Choices ........................................................................................................................................ 40 4.5.2 Biofouling and Corrosion Control ............................................................................................................... 41

5. TESTING ........................................................................................................................................................... 42

5.1 INITIAL SET UP: ...................................................................................................................................................... 42 5.2 TESTING PROCEDURES: ............................................................................................................................................ 45

5.2.1 Savonius Turbine: ....................................................................................................................................... 45 5.2.2 Darrieus Turbine:........................................................................................................................................ 46 5.2.3 Gorlov Turbine:........................................................................................................................................... 47

6. RESULTS ........................................................................................................................................................... 49

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6.1 SAVONIUS TURBINE ................................................................................................................................................ 49 6.2 DARRIEUS TURBINE ................................................................................................................................................. 50 6.3 GORLOV TURBINE ................................................................................................................................................... 51

7. CONCLUSIONS .................................................................................................................................................. 52

7.1 AIRFOIL PROFILE ..................................................................................................................................................... 52 7.2 PULSING/VIBRATING ............................................................................................................................................... 52 7.3 ANGLE OF ATTACK .................................................................................................................................................. 52 7.4 MANUFACTURING .................................................................................................................................................. 52

8. FUTURE CONSIDERATIONS ............................................................................................................................... 53

8.1. POSSIBLE FUTURE APPLICATIONS .............................................................................................................................. 53 8.2. GENERATOR IMPROVEMENTS ................................................................................................................................... 53 8.3 AIRFOIL IMPROVEMENTS .......................................................................................................................................... 53

APPENDIX A: WORKS CITED ................................................................................................................................. 54

APPENDIX B: BILL OF MATERIALS ......................................................................................................................... 55

APPENDIX C: PROJECT BUDGET ............................................................................................................................ 56

APPENDIX D: SCHEDULE (GANNT CHART) ............................................................................................................ 59

APPENDIX E: HOURS WORKED ............................................................................................................................. 60

List of Figures

FIGURE 1: EXAMPLE OF HORIZONTAL AXIS WIND FARM IN CALIFORNIA 2 FIGURE 2: SAVONIUS TURBINE 3 FIGURE 3: DARRIEUS WIND TURBINE 4 FIGURE 4: GORLOV HELICAL TURBINE 5 FIGURE 5: EFFICIENCY OF DIFFERENT TURBINE TYPES 6 FIGURE 6: INITIAL DESIGN 7 FIGURE 7: PRELIMINARY DESIGN - SIDE VIEW OF TURBINE HOUSING BODY WITH TURBINE TEMPLATE 8 FIGURE 8: PRELIMINARY DESIGN - INTERCHANGEABLE TURBINE AXIS 9 FIGURE 9: COMPUTER ENGINEERED DRAWING OF FINAL TURBINE HOUSING DESIGN 10 FIGURE 10: COMPUTER ENGINEERED DRAWING OF TURBINE HOUSING WITH GORLOV TURBINE 10 FIGURE 11: COMPUTER ENGINEERED DRAWING OF THE DARRIEUS TURBINE 12 FIGURE 12: COMPUTER ENGINEERED DRAWING OF THE GORLOV HELICAL TURBINE 13 FIGURE 13: COMPUTER ENGINEERED DRAWING OF THE SAVONIUS TURBINE 13 FIGURE 14: TURBINE HOUSING DURING WELDING 15 FIGURE 15: BEARING HOUSING 15 FIGURE 16: HOT WIRE CUTTING OF DARRIEUS BLADES 17 FIGURE 17: FOAM CUTOUT OF DARRIEUS BLADE 18 FIGURE 18: APPLICATION OF FILLER MATERIAL TO DARRIEUS BLADE 19 FIGURE 19: FIBER GLASSING OF DARRIEUS BLADE 19 FIGURE 20: EXTRA FIBER GLASSING ON THE DARRIEUS BLADE 20 FIGURE 21: DARRIEUS BLADES DRYING AFTER FIBER GLASSING 21 FIGURE 22: DARRIEUS BLADE AFTER INITIAL FIBER GLASSING 21 FIGURE 23: PNEUMATIC SANDING OF FIBER GLASSED BLADE 22 FIGURE 24: PNEUMATIC SANDING OF FIBER GLASSED BLADE 22 FIGURE 25: REMOVING FOAM FROM DARRIEUS BLADE TIPS 23 FIGURE 26: DARRIEUS BLADES PREPPED FOR MOUNTING FOAM 23 FIGURE 27: SUPPORT FOAM IN DARRIEUS BLADE TIP 24 FIGURE 28: THE TEAM TAPPING HOLES 25 FIGURE 29: DARRIEUS BLADES AFTER PRIMING 25 FIGURE 30: FILLING PINHOLES FOUND AFTER PRIMING 26 FIGURE 31: DARRIEUS BLADES AFTER PAINTING 26 FIGURE 32: COMPLETED DARRIEUS TURBINE (TOP VIEW) 27 FIGURE 33: COMPLETED DARRIEUS TURBINE (SIDE VIEW) 27 FIGURE 34: GORLOV MOLD BEING CUT WITH CNC 28 FIGURE 35: COMPLETED GORLOV MOLD 29 FIGURE 36: FIRST GEL COAT ON GORLOV BLADE MOLD 30 FIGURE 37: TRI-AXIAL FIBERGLASS CLOTH 30 FIGURE 38: GORLOV TURBINE MOLD PREPARATIONS 31 FIGURE 39: OUTER FIBERGLASS COAT OF BLADE ON THE MOLD 32 FIGURE 40: REMOVING BLADE FROM MOLD 32 FIGURE 41: BLADE AS REMOVED FROM MOLD 33 FIGURE 42: APPLICATION OF FILLER ON COMPLETED HALF OF BLADE 34

FIGURE 43: COMPLETED & PAINTED GORLOV BLADES 35 FIGURE 44: COMPLETED GORLOV TURBINE 36 FIGURE 45: COMPLETED GORLOV TURBINE 36 FIGURE 46: COMPLETED SAVONIUS TURBINE 38 FIGURE 47: DATA RECORDING DEVICE 39 FIGURE 48: SCREENSHOT OF LABVIEW SOFTWARE 39 FIGURE 49: PONTOON BOAT ATTACHMENT 40 FIGURE 50: UNDERSIDE OF PONTOON BOAT 42 FIGURE 51: BOLTING ON ATTACHMENT STRUCTURE 43 FIGURE 52: COMPLETED STRUCTURE BEFORE ATTACHMENT 44 FIGURE 53: ATTACHING TURBINE HOUSING 44 FIGURE 54: ARIEL PICTURE OF TESTING SITE 46 FIGURE 55: CHANGING THE TURBINES 47 FIGURE 56: TURBINE HOUSING WITH GORLOV BLADE INSTALLED 48 FIGURE 57: CHART OF TURBINE POWER BY CURRENT VELOCITY 49 FIGURE 57: BROKEN BLADE OF DARRIEUS TURBINE 50

List of Tables

TABLE 1: AVERAGED EXPERIMENTAL DATA FOR SAVONIUS TURBINE ........................................................................ 49 TABLE 2: AVERAGED EXPERIMENTAL DATA FOR DARRIEUS TURBINE ......................................................................... 50 TABLE 3: AVERAGED EXPERIMENTAL DATA FOR GORLOV TURBINE ........................................................................... 51

Executive Summary

The goal of Team Constant Contact is to design and construct the most efficient vertical-axis turbine for renewable energy in marine applications. During the initial testing phase, multiple turbine types will be tested to determine the most efficient configuration for our application. During the second phase, our team will fabricate a buoy configuration using the chosen turbine and deploy it for field testing. The entire project will be completed within the $1200 budget provided by Florida Tech.

The team constructed three different turbine designs based off of two different principles, drag and lift. The drag type turbine was a Savonius turbine. This is a very basic turbine that has multiple “cups” that catch the water and spin the turbine. The second turbine that the team researched and constructed was a Darrieus turbine. This turbine uses the principle of lift to propel its rotation. Using blades based on a simple airfoil shape, the turbine has the ability to use its lift and spin faster than the fluid flow. The last turbine we researched and constructed was the Gorlov Helical turbine. The blades in this turbine are in a helical shape. The advantage of the helical shape is that at least one part of the blade will have constant contact with the fluid flow allowing for efficient spinning of the blade.

A turbine housing structure was designed and constructed to test the turbines in an area of free fluid flow. The turbine housing was constructed with an incorporated pulley system and ac motor. The pulley system created a 1/8 ratio from the turbine to the motor. The turbine housing allowed for the turbines to be switched out easily with a system of flanges that could be connected to each of the turbines. Another structure was designed and constructed to attach the turbine housing to the pontoon boat. This structure was designed to safely handle, with a safety factor of 3, the drag forces that would be created by the entire submerged structure. The testing was done in the channel on the west side of the Indian River Lagoon next to FIT anchorage. Each turbine was placed in the turbine housing and run for 20 seconds at speeds ranging from 1-4 mph.

The results showed that the airfoil style turbines have a great ability to produce power. The Darrieus turbine produced the highest RPM’s. The Gorlov turbine produced much less power but also had a starting speed of 1 mph compared to the Darrieus which had to be at a minimum of 2 mph while still not being easy to start rotation. The Savonius turbine produced the least amount of RPM’s but due to its “cup” like shape, it had enough torque to produce the second most electrical power.

The airfoil shape and angle of attack were two considerations for the Gorlov and Darrieus turbines that were not adequately addressed in the construction of the turbines in the project. For continuation of the research these two factors should be normalized and tested again in this structure for a more accurate comparison of the two turbine types.

1. INTRODUCTION Team Constant Contact was formed in January of 2009 as a senior project for a group of ocean engineers interested in renewable marine energy. The project that Team Constant Contact presented was a device that harnessed energy from ocean currents using a vertical axis. The team used their device to test multiple vertical-axis turbines in a marine environment.

1.1 Motivations

Team Constant Contact is motivated by the prospects of vertical-axis marine turbines as a source of renewable energy. This team is motivated to increase the amount of research on vertical axis turbines.

1.2. Objectives

The objective of Team Constant Contract was to develop and present a final product that was well researched, designed and manufactured. This product would be optimized by testing a number of blades to find the best fit for the application. The device produced will produce an ample amount of electricity to power a variety of applications.

1.3. Organization

Team Constant Contact was organized as follows:

• Joshua Lappen: Team Leader

• Travis Schramek: Blade Design and Research

• Geordy Smit: PRO/Engineer Drawings and Design, Generator Selection

2. Background

2.1 Previously Existing System

2.1.1 Wind Systems

The use of turbines as a power source began in rural areas after their initial application to activities such as grain grinding and pumping water. This technology fell to the way side once electric grids spread to the areas using the wind turbines. Throughout a majority of the twentieth century wind power was strictly used to charge batteries and creating powers for very remote areas (Burton, Jenkins, Sharpe, Bossanyi, 2001). Many federally funded research projects in renewable energy emerged in the U.S. in 1973 when oil prices spiked. This push in the field of renewable energy helped develop large scale prototypes of both horizontal and vertical axis turbines.

The UK, Germany, Canada, and Sweden also pushed for advancements in this field. The Danish 3 blade design is easily recognizable as the most common turbine used within the current wind power industry. This style of turbine uses a fixed-speed drive train, and with its simple architecture it has ability to produce 1.5 MW when having a 60m radius (Burton et al, 2001).

Figure 1: Example of horizontal axis wind farm in California

(http://www.pollutionissues.com/Ec-Fi/Electric-Power.html)

Large wind turbine projects usually consist of the traditionally more efficient horizontal axis windmills. However, the vertical axis turbines (VATs) are becoming widely used in smaller, private applications. They can generate electricity with less wind and less space. Having a vertical axis turbine means you don’t need extra space for the large horizontal prop to spin. Another advantage is that the entire structure does not have to move to catch the wind. The large windmills need to mechanically turn into

the wind which takes electricity. Vertical axis turbines are also better suited for urban areas or poorer countries that need basic electricity needs (Hurst, Vertical Axis Turbines: The Future of Micro Wind?, 2008).

2.1.2 Marine Type Systems

Marine turbines have been in service for many years carrying out similar activities to the original wind turbines. Innovation in the field began to occur during the Industrial Revolution ( Burton et al, 2001). In this time period new principles and materials were applied to help improve the efficiency of the turbines of the day. Most marine turbines, primarily water wheels, held the disadvantage of being quite large. This was necessary for them to produce sufficient amounts of power. The principles of these turbines have been built upon for some time to help create today’s hydro power industry.

In the development of the ocean energy industry multiple types of devices converted have been from other applications. While having its basis in the water wheel today’s hydro power industry has taken large amounts of insight from the development of wind energy systems. The evolution of wind energy has showed engineers today the advantages and disadvantages of different devices used within the industry. The development of Vertical Axis Turbines (VATs) was done mostly in the field of wind energy where new designs and theories have been tested to develop many efficient turbine set ups. The deployment of these VATs to the marine arena has allowed for more efficient energy extraction from sources of renewable energy.

Drag-Type Turbines

The most basic styles of vertical axis turbines are based off of the principle of drag. The Savonius turbine is the best example of this type (Figure 2). The turbine blades act as cups, catching the fluid as it moves which then moves the turbine around the central axis. These turbines cannot spin faster than the velocity of the fluid medium that they are in due to this design. The curvature of the back side of the blade allows for the turbine to spin easily into the flow.

Figure 2: Savonius Turbine

(Source: http://farm1.static.flickr.com/48/115831820_b0574cf7e3.jpg)

Lift-Type Turbines

The Darrieus Turbine

This style of turbine, shown in Figure 3, was patented in France in 1925 and in the US in 1931 by Georges Jean Marie Darrieus (Darrieus, 1931). Two curved airfoils are attached to a central axis which they rotate around. The lift force created can pull the blades of the turbine around at a speed greater than the current flow (Gorlov, 1998). This allows the turbine to spin at high rpms. Used in the wind application, this blade type is not self starting. Research has been done to try and develop a self starting form of the Darrieus turbine but none have been completely successful in applying them to real world conditions but no drastic innovations have been made (DeCoste, McKay, Robinson, Whitehead, & Wright, 2005). A small motor is needed to help start the rotation of most basic styles of this VAT. Once the rotation is started, wind movement over the blades can create enough torque to continue the blade movement. Although it has its problems, this blade style was still the prominent blade on the market for marine applications until the mid to late 90’s. Due to fact that the density of water is roughly 850 times larger than that of air, the velocity of water can be much less than the velocity of air to result in the same power production (Borgnakke, Sonntage, 2009). The higher fluid density results in more torque with the blades, allowing the turbine to be self starting and eliminating the need for a motor to initiate the rotation of the turbine.

Figure 3: Darrieus Wind Turbine

(Source: http://www.solarnavigator.net/images/wind_turbines_Darrieus_windmill.jpg)

A variation of this turbine that was within Darrieus’ patent was the H bar style. Instead of the blades being curved and attached to an upper and lower section of the central axis support, the blades were straight and connected with a cross support (Darrieus, 1931). This set up creates the appearance of an H. The original design had two blades. When fluid flows through the turbine there is a point where the two blades are in a position where the flow no longer encourages rotation causing a stall point (DeCoste, McKay, Robinson, Whitehead, & Wright, 2005). The addition of one or more blades eliminates this design flaw. Analysis of the correct number of blades for this style of turbine has been done by Dalhousie University’s Department of Mechanical Engineering and a 3 blade set up was deemed as the most powerful and efficient (DeCoste et al, 2005 ).

The following companies currently using the Darrieus turbine in marine applications today: Alternative Hydro Solutions Ltd, New Energy Corporation, Blue Energy Company.

Gorlov Helical Turbine

Figure 4: Gorlov Helical Turbine

Source: (Gorlov, 1998)

The Gorlov Helical turbine was based off of the principles and original shape of the Darrieus turbine. The Gorlov turbine (Figure 4) has a helical shape. When fluid flow moves through this turbine the helical shape assures that there is always some part of the turbine’s blades making contact with the flow. This unique characteristic has eliminated the pulsation of the turbine, which occurs with the Darrieus turbine (Gorlov, 1998). With the manipulation to the design an increase in efficiency and speed resulted which can be seen in Figure 5. This turbine was invented by Alexander M. Gorlov, a Mechanical Engineering Professor at Northeastern University in Boston, MA. He has received the Edison Patent Award for this design. This helical form has been thoroughly tested at the University of Michigan (Gorlov, 1998). Current companies such as GCK Technology and Hydrovolt have used these turbines in field applications.

Figure 5 below shows a comparison of the efficiencies of Different Marine-Type turbines.

Figure 5: Efficiency of Different Turbine Types

Source: (Gorlov, 1998)

3. Design

3.1. Design Evolution

3.1.1 Initial Design

The initial design goals were to create a very simple structure to harness a vertical axis turbine. The initial design had no intended applications; it was simply a versatile power device.

The initial design (Figure 6) consisted of a steel frame consisting of piping sandwiched between two plates. The single turbine in this device was the Gorlov Helical Turbine. It would transfer the mechanical energy harnessed from the ocean to a generator contained in a pressure housing (grey). Floatation would be provided by syntactic foam located on the top of the structure. The entire device would have been anchored at a depth of 5 ft below the water line.

Figure 6: Initial Design

The initial design had a variety of problems:

1. It provided no opportunity for experimentation with confined flow.

2. The possibility of rotation of the entire turbine housing.

3. The restriction to test and use only one type of turbine.

4. The steel frame would be heavy and corrode quickly.

A secondary preliminary drawing was drawn with a closed structure. However, after consulting with Dr. Ron Reichard, it was decided that a closed structure was not an option. He provided insight into the workings of the fluid mechanics of airfoil type turbines. Airfoil type turbines are based on the principle of creating pressure. By creating a confined flow, the device would alter the pressure around the turbine. The altered pressure would reduce the function of many of the blade types we wished to use. He informed us that the only time in which a confined flow should be used, is when using a drag-type turbine.

3.1.2 Preliminary Design

The preliminary design was drawn out to solve the problems in the initial design. This design incorporates a structure for two purposes:

1. To be mounted to the front of the pontoon boat for testing of multiple turbine configurations under multiple flow speeds.

2. To be modified into a buoy, using the turbine found to be the best for the application.

The two very different purposes require a versatile turbine housing structure. The turbine housing of this design was comprised of an Aluminum frame connected using tees and elbows. This frame will be made up of 1.25 inch, schedule 40 aluminum piping for structural stability and corrosion protection. Figure 7 shows a preliminary drawing of the structure.

Figure 7: Preliminary Design - Side View of Turbine housing body with Turbine Template

The turbine shaft would have been attached to the turbine housing through a machined bracket. This bracket would have been machined out of an aluminum rod and will house two bearings. The bracket was to be welded to the turbine housing. Designs of this bracket have been completed.

The initial design stated that there would be two mounting systems: a pontoon boat mounting system and a buoy conversion system.

On the central axis there was an interchangeable section that will allow for easy switching between blades. Flanges connected these blade attachments. Figure 8 below shows a template for an interchangeable turbine axis.

Figure 8: Preliminary Design - Interchangeable Turbine Axis

The three experimental blades that the preliminary design called for testing are the Lenz2 Turbine, Darrieus Turbine and Gorlov Helical Turbine. Each experimental turbine had a maximum height of 24 inches and a diameter of 16 inches.

3.2. Final Design

The final design chosen for use in the project is very similar to the preliminary design described in Section 3.1.2 Preliminary Design.

3.2.1 Turbine Housing

The turbine housing of the device is simple and modifiable. The purpose of the turbine housing is to provide support for the mechanisms of the device, as well as provide a versatile mounting surface. By creating a simple structure that has versatile mounting surfaces, the device will have many applications.

The turbine housing is constructed using welded aluminum piping. The aluminum piping is 1.25” nominal, schedule 80, 6065-T6 aluminum piping.

Figure 9: Computer Engineered Drawing of Final Turbine housing Design

Figure 10: Computer Engineered Drawing of Turbine Housing with Gorlov Turbine

3.2.2 Bearing

At the ends of each of the support shaft is a bearing setup. The bearings selected are 1” I.D. flanged, sealed bearings. They will be lubricated using waterproof grease. Each support shaft is held in place using two bearings. This system requires two bearings for stability because the central turbine shaft is removable.

3.2.3 Shaft System

The shaft of the turbine is separated into upper, middle and lower sections. The upper and lower sections are considered support shafts and are held in place using bearings. The central shaft is the interchangeable turbine shaft.

The upper and lower support shafts are comprised of 1” aluminum round. This will provide a stable platform for the turbine shaft to attach to. The upper shaft will also be attached to a pulley system to transfer rotation to the generator.

The middle interchangeable turbine shaft is comprised of 1.25” nominal aluminum tubing. The interchangeable turbine shaft is bolted to the upper and lower sections by way of flanges. By using this system, each turbine can easily be removed during the testing phase.

3.2.4 Turbine Design

Each turbine is built around its own turbine shaft. As described in section The design called for a bent aluminum frame. After a discussion with a Bill Bailey we determined that the Schedule 80, 6065-T6 1.25” nominal Aluminum piping could not be bent to 90 degrees at the specified radius. This called for a change in the design and the addition of aluminum elbows. All straight sections of the housing were cut out of the original Aluminum piping. The supports connecting the two square frames were milled to fit snuggly onto the piping to allow for good welding. The final dimensions of the structure are 29”x33”x24”.

Figure 14: Turbine Housing during welding

each turbine shaft is bolted to the upper and lower support shafts. Specially built arms connect the blade to the turbine shaft. Each turbine will have a standard diameter of 16” and a length of 24”.

Darrieus Turbine

The Darrieus Turbine consists of 3 blade system. Each blade of the Darrieus Turbine is constructed with a shape of NACA 632-015 and a total blade length of 24”. This shape has been found to be one of the most commonly used foil shapes for Darrieus Turbines. The blade arms are manufactured to hold each blade at a 5° angle of attack. Figure 11 on the following page shows a computerize drawing of the turbine

Figure 11: Computer Engineered Drawing of the Darrieus Turbine

Gorlov Helical Turbine

The Gorlov Helical Turbine will consist of a 3 blade system. It has an airfoil shape defined by NACA 0020, a total blade height of 24”, and a pitch of 60 degrees. Figure 12 below shows a computerize drawing of the turbine

Figure 12: Computer Engineered Drawing of the Gorlov Helical Turbine

Savonius Turbine

The Savonius Turbine will consist of a 3-blade system. Each blade will be constructed from cut-up 55 gallon plastic drums. Figure 13 below shows a computerize drawing of the turbine

Figure 13: Computer Engineered Drawing of the Savonius Turbine

3.2.5 Pontoon Boat Mounting

The pontoon boat attachment structure was designed to follow many guidelines. The structure must hold the turbine housing completely submerged below the water surface. It may not hinder the steering of the pontoon boat. It was designed to avoid any modification to the pontoon boat. The team came up with a design that incorporated 2” aluminum square beams that would attach to preexisting holes in the pontoon boat structure.

4. Manufacturing and Construction

4.1. Turbine housing

The design called for a bent aluminum frame. After a discussion with a Bill Bailey we determined that the Schedule 80, 6065-T6 1.25” nominal Aluminum piping could not be bent to 90 degrees at the specified radius. This called for a change in the design and the addition of aluminum elbows. All straight sections of the housing were cut out of the original Aluminum piping. The supports connecting the two square frames were milled to fit snuggly onto the piping to allow for good welding. The final dimensions of the structure are 29”x33”x24”.

Figure 14: Turbine Housing during welding

4.1.1. Bearing

A 3” diameter solid cylinder of 6065-T6 Aluminum was used as the bearing housing. The outer edge was shurred up to create a flush surface to work off of. The inner area was milled out on the lathe to the outer diameter of the bearings. The milled aluminum bearing shaft was then welded onto square flanges that had been cut out of a stock aluminum plate on the CNC machine. The bearings were then press fit tightly into place. The final product can be seen in Figure 15.

Figure 15: Bearing Housing

4.2. Turbines

4.2.1. Darrieus Turbine

Hot Wire Cutting:

The initial plan for the Darrieus turbine was to cut each individual blade out of foam using a jig. A large amount of foam was found in Dr. Wood’s lab that he said the team could use for these blades. First, a hot wire cutter was used to cut the large block, which was originally 3’ x 2’ x 2’, into smaller pieces so cutting each blade on the jig would be easier.

To cut the blocks evenly, lines were drawn along the edges of the blocks to cut our three 3’ x 8” x 14” blocks. Josh and Travis used the wire cutter together and attempted to cut out the three bocks evenly. After each of the blocks was cut they were examined. Each one had ridges and was not square. The team decided it would be best to contact Alan Shaw for advice on using a hot wire cutter. The team went with Wet Mobile Watts when they were meeting with Alan Shaw and discussed their problems of squaring the blocks with Mr. Shaw. After further discussions within the team, Alan Shaw was contacted again to see if he could help with the cutting of the airfoil blades. After Alan Shaw offered his help, the team met with Mr. Shaw to cut out the airfoils. In preparation for the meeting two identical air foil shapes were cut out of aluminum sheeting on the CNC machine to be used as the templates for the blades. A small squared block with usable dimensions was found and Bill Bailey gave the team the OK to use it.

A grid was drawn of the sides of the desired block of foam to hot wire cutting the airfoils. This grid was used to line up the templates on both sides. The templates had predrilled holes so they could be nailed to the foam in the correct location on the block.

The templates were lined up on the grid on the sides of the foam block and were then stuck on with short nails. The hot wire cutter was then turned on and the heat was tested on a spare block of foam.

Alan said when the heat was correct and told Josh and Travis that the line must be fairly taunt to prevent the ridges that occurred on their previous attempt at hot wire cutting foam. Lines were drawn at ¼, ½, and ¾ down the template. These markings allowed for the individuals on both sides of the block to move around the template at the same speed. The wire cutter was held by Alan and Travis on both sides of the block.

Figure 16: Hot Wire cutting of Darrieus Blades

For the first blade the wire came in the top edge of the block. Alan called out the points along the stencil he was at. The wire ran along the Aluminum stencil cutting the correct shape (Figure 16). The cut was continued past the end of the tailing edge then back towards the stencil and around the bottom portion. This ensured the edge would be straight and not be rounded by the slack in the wire. The wire was lead slowly around the leading edge of the template and back out of the block where the wire began the cut.

Figure 17: Foam cutout of Darrieus Blade

Glassing:

West Systems Epoxy Resin and Harder were used to glass the Darrieus blades. To begin the glassing process a mixture of epoxy resin, harder and micro-balloon, called slur, was made. This was spread over the airfoils to reduce the amount of resin they would soak up and add strength to them. After this had been applied a mixture of West 205 Epoxy Resin and 206 Hardener was mixed with a small amount of micro-balloon.

Figure 18: Application of filler material to Darrieus Blade

Sheets of unidirectional cloth were cut so the main strands will extend along the span of the airfoils. This type of cloth and cut gave added strength for compressive and tension forces along the span of the airfoils. The strips of cloth were paced over each of the four blades and were covered with the mixture that had just been made (Figure 19). The cloth soaked up small amounts of the slur and so little mixture was needed to squeegee the resin throughout the cloth.

Figure 19: Fiber glassing of Darrieus Blade

A second layer of the same cloth was added and over the first and the resin was moved over the glass with the squeegee. Eight 6”x3” pieces of bi-directional cloth were cut for the ends of each blade. These pieces gave added thickness to the glass on the ends and more importantly strength for attaching the blades to the turbine itself. The pieces of cloth were placed on the blades and more resin hardener mixture was spread over them. The difference in the types of glass and their fiber orientation can be seen in Figure 20.

Figure 20: Extra Fiber glassing on the Darrieus Blade

Duck tape was lined along the edges of a flat bench. The blades were then moved to this bench and the trailing edges were placed along the lines of duck tape. Small wedges were used to prop the leading edges up forcing the trailing edges to rest on the table as they cured (Figure 21). This caused the trailing edge, which needed to be thin and flat in the final product to have a nice defined line. These were left overnight to cure.

Figure 21: Darrieus blades drying after fiber glassing

Figure 22: Darrieus Blade after initial fiber glassing

The following day the edges of the dried cloth were cut off with a pneumatic saw and sanded by hand with 120 grit sand paper. The trailing edge was the most important part of the next step. A pneumatic sander was used to remove a small amount of foam from the trailing edge (Figure 23). This allowed for the formation of a resin pool and allowing the cloth on one side of the blade to sit close to the cloth on the other side making the edge tighter and more rigid. The same process that was done to initially glass the first side was repeated for the second side.

Figure 23: Pneumatic Sanding of Fiber glassed Blade

After the second side had dried each turbine blade was sanded with 120 grit sand paper. The leading edge was then glassed with bi-axial glass cut on a 45 degree angle. This type of glass and orientation prevented the blades from breaking in half on the leading edge which is the area that takes a majority of the force. Putty was used to fill any small pinholes or dings in the fiberglass and was then sanded down for a smooth finish on the blades (Figure 24).

Figure 24: Pneumatic Sanding of Fiber glassed Blade

One inch measurements were marked off of the ends of each blade. A pneumatic grinder was then used on the inside of the blade to remove the foam from the end all the way to the 1” line (Figure 25). This was being done to allow for the formation of a solid end cap that could be used to attach the blades to the turbine. Once all the foam had been removed a slow curing epoxy resin/hardener mix was applied to the inside of the ends of the blades (Figure 26).

Figure 25: Removing foam from Darrieus Blade tips

Figure 26: Darrieus blades prepped for mounting foam

Crow’s foot weave cloth was cut into squares to fit into the open ends of the blades. Once the mixture was applied to the inside of the blades the cloth was placed inside and then wetted with the mixture into place. The blades were then left overnight to cure. The next day the ends were then trimmed to be flush with the original end marking. Small block of 40 lb density, very high density, foam were cut to be placed into the ends of the blades (Figure 27). The holes that would be made to attach the blades would be drilled and tapped into these blocks.

Figure 27: Support foam in Darrieus blade tip

Chop glass and micro-balloon were mixed into an epoxy resin and hardener combination to fill these ends and make them solid. Team Constant Contact can be seen working together to fill the ends of these blades (Figure 28). After the end caps had time to cure the holes were drilled 1 5/8” from the leading edge down the center line of the blades. A second hole was drilled 1 ½” down the line from the first hole on the ends of each blade. These holes were then tapped. After they were tapped screws were placed in the holes of each blade and they were hung in a latter for their first layer of primer.

Figure 28: The Team Tapping Holes

Prime and Painting:

After the first layer of gray primer the blades were sanded and then putty was applied to the imperfections on the blades. The blades went through the putty and sanding process 3 times before they reached final paint (Figure 31).

Figure 29: Darrieus Blades after Priming

Figure 30: Filling Pinholes found after priming

Figure 31: Darrieus Blades after Painting

The Blades were then painted with a white gloss paint that is normally used on aircraft. After two coats of paint the blades were completed.

Final Assembly:

The turbine arms were created in PRO/Engineer. The arms were cut out on the CNC Machine by Bill Bailey. The arms were then spaced by 24”, the length of the Darrieus turbine blades, and welded onto the central axis. The arms had holes cut for attaching the blades in them from the PRO/Engineer drawing so small aluminum screws were used with washers to finish assembling the turbine.

Figure 32: Completed Darrieus Turbine (Top View)

Figure 33: Completed Darrieus Turbine (Side View)

4.2.2. Gorlov Helical Turbine

Design Process

These turbine blades could be cut out by hand using a hot wire cutter. After developing the procedure for the construction of the Darrieus turbine, the team deemed this idea unpractical. The next best option for the team was to try and create a mold to pop the blades off from. This mold needed to be cut out by a CNC machine to make sure the dimensions of the blades were followed correctly. The team knew of a company located on the space coast named Vector Works Marine Inc. who had large 5 axis mills. Contact was made with Janelle Boisvert, an FIT Ocean Engineering graduate, at VectorWorks.

Janelle spoke with her supervisors and they cleared the project at no cost to the team. After initial designs were sent to Vector Works and they created a design for the molds using their modeling programs. The blades were to be created with two separate female molds, one for the outer section and one for the inner section. The blades were symmetrical throughout the length which would allow the molds to be placed together during the blade construction process. Travis met with Janelle and Mark at their location in Titusville and toured the facilities and discussed the construction process further.

Construction Process

The correct type of foam for the mold was designated when Travis made the initial visit, a 4lb density trymer foam. The low density foam would be easy for the mill to cut and allow the milling to run unsupervised. Initial cost estimates for the foam ran from $900- $1400. After talking to a wide range of foam producing companies the team found ITW Insulations on the internet and Mel Rasco became the teams contact in the company. Mel offered the foam free of cost including shipping and had it sent to VectorWorks on June 26th. The foam came in as Two 12”x12”x 33” blocks of 4lb trymer foam as ordered. The foam was received by VectorWorks on Monday June 29th and it was placed on the mill for the first time on July 1st. By having low density foam Vector Works was able to set up the mill and the program and run the cutting process at night. The molds were placed on the mill a second time on July 8th. Final cuts were made to sure up the edges and the molds were completed. The molds were then picked up and later taken to Alan Shaw’s hanger to begin the construction of the blades.

Figure 34: Gorlov Mold being cut with CNC

Figure 35: Completed Gorlov Mold

The molds were finely sanded with 120 grit sandpaper to take away the ridges left by the 1”bit used by the mill. After the sanding was complete a mixture of West 205 Epoxy resin and 206 hardener was mixed with the addition of micro-balloon to help fill the pores of the foam. The foam was then coated with the mixture. As the mixture was being created two 14”x33” pieces of crow’s foot weave 8 oz cloth was cut at a 45 degree angle, along the weave line, and prepped for placement on the molds. Once the mixture was thoroughly spread the cloth was placed onto the molds. The 45 degree cut allowed the edges of the cloths to fold over the sharp edges of the molds. Another mixture of 205 West Resin and 206 Hardener was made and applied to any spots that had not yet soaked up resin from the foam (Figure 35). After resin had been spread over the mold a small squeegee was used to spread any of the pools of resin that had formed.

The mold was allowed to set and then bias sanded with 90 grit sand paper to reduce ridges and bubbles while keeping the contour intact. Another session of filling with putty was done and sanded again. Two coats of gray primer were sprayed on the molds to help revile any pinholes and inaccuracies in the contour and leading edges on the molds. Two sessions of sanding and putting followed before the final 2 coats of primer were applied. The molds were cut by Vector Works 2mm larger than the planned size of the blades to allow for the buildup of fiberglass and paint on the mold. The mold was then complete.

Figure 36: First Gel Coat on Gorlov Blade Mold

Figure 37: Tri-axial Fiberglass cloth

The flange of the mold was covered with painters tape to prevent from damaging the outside of the mold while making parts. Three to six coats of release agent, depending on thickness of the coats, were sprayed onto the mold and allowed 5 minutes to dry. An initial coat of white/yellow gel coat was sprayed in each mold once the release agent had cured (Figure 36). While this initial prep of the mold was being done fiberglass cloth was being prepped. A layer of tri-axial cloth (Figure 37) was laid on the

inside of a crow’s foot weave. This allowed for maximum support with a quick production time. The two sheets for each side of the mold were laid onto each other and then onto a piece of sulafane. They were wet with a fast curing polyester resin hardener mix while on this sulafane. This allowed for the application to be smooth and quick. Fiberglass chop was cut into 6”x1” pieces for each end of each mold. Once the gel coat was dried the 6”x1” pieces were placed on the end of each mold and wet with a polyester resin hardener mix (Figure 38). Once these end pieces were soaked, the pre assembled cloth set up was placed on the turbines with the crow’s foot weave lying on the gel coat. The suliafane was then removed from the back and the cloth was smoothed out with a small amount of resin on a brush (Figure 39). The molds were then moved into the sun and left to dry.

Figure 38: Gorlov Turbine Mold Preparations

Figure 39: Outer Fiberglass Coat of Blade on the mold

Approximately 25 minutes after they were placed in the sun the molds were brought back inside the hanger. The fiber glass was hot to touch but almost completely cured. A fan was placed on the molds to cool the blades and prep the tool for removal of the molds. After 5 minutes the molds were cool enough to remove and a small wedge was run around the outside of the fiberglass removing them (Figure 40). The two blades were placed together to allow them to cure more and hold their shape (Figure 41).

Figure 40: Removing Blade from Mold

Figure 41: Blade as removed from mold

The same process was repeated for the next set of parts on the molds. While this process continued the edges of the already molded parts were cut with a pneumatic jig saw and band saw. Micro-balloon and polyester resin was mixed as filler for the insides of the blades. A large volume of micro-balloon was used to keep the density of the filler low. A denser mix of polyester resin and chopped glass was mixed to fill in the ends of the blades for a more rigid support to connect into.

Once the second set of parts had dried on the mold the filler was placed inside the blades cavity as well as in the parts that had been trimmed (Figure 42). The trimmed parts were then placed onto the parts still in the mold and compressed to form the blade. The blades were held down with light sand bags that would not harm the finish of the blades. These parts were left to dry overnight and in the morning the blades were popped off of the molds.

Figure 42: Application of filler on completed half of blade

The edges were cut with the pneumatic jig saw and then the blades were sanded lightly by hand with 200 grit sand paper. As this was occurring the process for making parts in the mold began again. Once the two parts had cured they were removed from the molds. The edges were then cut down and the same two fillers were made for this final blade. The blade was filled and clamped together and left overnight to dry. After wet sanding this blade the three Gorlov blades were complete (Figure 43).

Figure 43: Completed & Painted Gorlov Blades

The arms connecting the blades to the central axis were made from 1”x1/8” Aluminum rod. The rode was cut into six 7.5” sections and six 3” sections. These 3” pieces were welded perpendicular to the 7.5” pieces creating the “T” style arms that were desired. ¼” holes were drilled in the 3” sections of the arms to allow for the blades to be connected. An end mill was used on the 7.5” section to create the necessary curvature so they could be easily welded to the central axis.

Three arms were connected to one side of the turbine blades with 1/8” width screws. The team then helped to line up the arms correctly on the central axis with Bill Bailey. Bill then welded the top arms in

place. The turbine was then flipped over with the arms being held by just the top arms. The arms for the bottom were then lined up in their proper position and were welded in place. The bottoms of the blades

were then predrilled and screwed in. The Gorlov Turbine was then complete (Figure 44 & Figure 45).

Figure 44: Completed Gorlov Turbine

Figure 45: Completed Gorlov Turbine

4.2.3. Savonius Turbine

The construction process for the Savonius was divided into three parts; the blades, the wood attachment, and the central axis. The central axis, or turbine shaft, was constructed first, followed by the wood attachment, and then the blades. The last step was assembling everything together.

The shaft of the turbine was made first out of 6065-T6 aluminum. Using the lathe, the ends of the shaft had to be cut down so the flanges would fit on a little lip. This was welded onto the end and would be the flange that attaches the turbine to the superstructure. Then another flange was welded on the bottom, 3 inches above the other, so the bottom wood attachment would slide down the shaft and sit on the flange. Since the original turbine was going to be a Lenz 2, and the flanges were already cut out and there was a design flaw with the flanges. There should have been only three holes (instead of four) cut out so that each blade could be attached on the inside to the flange with their own hole and be exactly 120 degrees apart.

The wooden attachments were cut out next. Each is a 24 in. diameter circle with the center hole for the axis. Once these were completed, it was time to start making the blades. The blades were cut out of a 55 gallon plastic blue drum. They were cut out to be 24” long and have an 8” cord length. Using a 90 degree piece of aluminum, brackets were made to screw into the wood and attach the turbine blades to it. Next, 120 degrees had to be marked on the wood to make sure the blades were exactly symmetrical. From there, it was just figuring out a way to make all the blades even and parallel to the axis and attach to each wood attachment. One problem was that the screws that were planned to attach the blades to the inside could not be used as planned because the flange was in the way of where the screws came out in the bottom. To compensate for this, some screws had to be attached more towards the outside of the blade. This created a space between the blade’s edge and the shaft since the screw wasn’t holding it all the way on the inside. Once everything was attached, and the holes were in place it was time to take the blades back off so the wood could be painted. After it was painted the blades were assembled one last time before the top flange on the shaft was welded on for the final

Figure 46: Completed Savonius Turbine

4.3. Power System

4.3.1. Generator housing

A circular aluminum plate was cut to attach the motor to. The plate was cut on the CNC machine with tapped holes for the four screws that the motor would be mounted with. Extended holes were drilled into the plate to attach the plate to the turbine housing. Marine sealant was used to coat each of the seals and screw holes to prevent water from entering the motor. A thin runner material was cut to form a gasket to help seal the top of the motor. A thin Aluminum plate was cut to hold the gasket to the motor and create a seal. Marine grade grease was packed around the motor’s shaft and the gasket and top plate were placed on the motor. The screws were then used to attach the motor to the plate. The marine sealant was then used to coat the edges for the gasket to help establish a better seal. The motor was left overnight to allow for the sealant to cure.

4.3.2 Data Recording System

Data for the experiment was to be in the form of voltage, current and Rotations-Per-Minute. In order to lower error within the experiment, the team approached Larry Buist to design and build a device that would record the data accurately and automatically. Larry Buist created a device that records the data (Figure 47) and sends via serial cable to a computer with LabVIEW software. The LabVIEW program (Figure 48) written by Mr. Buist then both displays the data and records it to a data file.

Figure 47: Data Recording Device

Figure 48: Screenshot of LabVIEW software

4.4 Pontoon Boat Attachment Structure

After the requirements were known, measurements were taken on the boat that was designated for us. The boat had previous drilled holes in aluminum beams under the deck of the boat. The holes were measured so that the holes that were to be in the attachment structure would line up. Material was ordered and the cost was split with Team Sharks so they could use the structure also for their testing. Once the material was received, beams were cut to size so that Bill Bailey could set up and weld the

structure together easily. When the structure was complete and it was time to test, it was attached to the pontoon boat. This went flawlessly as all the holes lined up and the structure was set to test.

Figure 49: Pontoon Boat Attachment

4.5 Materials

4.5.1 Material Choices

The frame was constructed out of 6061 T6 marine grade aluminum. Aluminum is a strong, light metal. Since the system needs to float, aluminum is a much better choice than steel which is cheaper but much heavier. The design was tested in a fairly calm environment so this aluminum held up perfect. The team also thought about using composites for the frame however, although it is cheaper and lighter, the manufacturing of the frame with composites would have been a daunting task. Five and 6000 series aluminum are considered marine grade because it is alloyed with magnesium that cuts down on corrosion. 6061-T6 aluminum uses precipitation hardening process that has magnesium and silicon as its main alloying elements. It has an ultimate tensile strength of 42,000 psi. Using TIG or MIG welding machines, this aluminum has good weld ability. This is important to us because our entire frame will be welded (Understanding Extruded Aluminum Alloys).

The blades were constructed out of foam, fiberglass and resin. The composite material blades were light but strong enough to hold through a swift current. The primary function of the blades was to be as light as possible with equally minimal resistance. If the project was to be manufactured for larger applications in the ocean, these blades would have to be made out of aluminum. This means more resistance, however with the larger scale project, strength becomes more important.

To get optimum current, the system needed to be designed to sit atop the water with the blades as high as possible in the water column. To do this, the weather buoy will be attached atop our frame. The buoy is made of foam filled PVC piping. The PVC is water tight and will not corrode. The foam gives it the floatation needed to obtain optimum current speeds. Attached to the buoy is an aluminum crown that will be used to connect the buoy to our structure.

To anchor the system in place steel chains will be attached to hooks on our frame. Then weights will be attached to the other end of the chain to anchor it down. Since the system needs to float in the same location, the chains will need to be tensioned in from to keep it stationary. This will have to be done on site and the weight will have to be determined depending the current speed at the location.

4.5.2 Biofouling and Corrosion Control

The system will be painted with antifouling paint. This is necessary because it will be at the water line, with some above, exactly where barnacles like to grow. The anti-fouling paint will keep sea life from growing on the buoy or frame. Any added weight to the structure will mean it will gradually sink, getting away from the area of current wanted. The blades will also have to be painted. The blades are more important because the weight of the blades is directly related to the resistance of the blades spinning. Also, the goal is to have any debris to glide right through our system.

The only possible corrosion on our device is on our steel ball bearings. The ball bearings chosen are sealed; however, grease will be added to the surface for corrosion purposes. The grease will help create a layer between the bearings and the damaging salt water.

5. Testing

5.1 Initial Set Up:

On Tuesday July 14, 2009 the team went to the boat ramp on the south side of the Melbourne causeway and launched the pontoon boat. The team transported the attachment structure to the boat ramp with Travis’ truck. Once the pontoon boat was in the water it was pulled along the side of the dock and the attachment structure was walked to the boat.

Once the structure was lined up with the correct holes 3/8” bolts and nuts were used to then attach the structure to the pontoon in the 6 predrilled locations (Figure 50 & Figure 51). The structure aligned correctly the first time and the team did not need to drill any new holes.

Figure 50: Underside of Pontoon Boat

Figure 51: Bolting on Attachment Structure

Once the system was on the docks the boat was pulled into the crew docks stern first to help prevent from running aground. Snorkeling equipment, a lap top, the speed gage and turbine housing were all brought about the pontoon boat.

Figure 52: Completed Structure before Attachment

Life preserves were attached to two places on the turbine housing. Two team members then entered the water in basic snorkeling gear. The turbine housing was then lowered into the water and moved into its position under the attachment structure (Figure 53). Eight U-bolts were then used to attach the structures together. This was done with the structure fully submerged so a mask and snorkel were used to make it easier.

Figure 53: Attaching Turbine Housing

Once the turbine housing was attached the current meter’s cord as well as the cord from the motor were zip tied to the structure leading them towards the boat. The speed gage was then hooked up to a battery onboard the boat. It was then turned on and program 3 was selected to read the water velocity. The computer was then turned on and LabVIEW was opened. The program written by Larry Buist was open. A team member in the water spun the turbine to make sure the computer was getting readings. Data was being received by the computer therefore the system was ready for testing.

5.2 Testing Procedures:

The following is the ideal testing procedures:

1. Attach the turbine into the device at the dock. 2. Position the boat in the channel. 3. Accelerate so the boat will be traveling at a speed of 1 mph. 4. Begin recording in Lab View program. 5. Record for 20 seconds 6. Repeat steps 2 to 5 at speeds of 2, 3, 4, mph.

5.2.1 Savonius Turbine:

The boat was driven at a slow speed until the team reached the channel leading out of the anchorage. The velocity meter was turned on and Lab View was prepared for the first test. The boat speed was increased until it was moving at a consistent 2mph. Once the boat was at speed, the program was used to begin recording data for approximately 20 seconds. Once this data was saved the boat speed was increased to 3mph. Data was then recorded again for 20 seconds. The engine was taken out of gear to make sure the data was recorded correctly which it was. The speed was increased to 4 mph and data was recorded for 20 seconds. The data was consistent through the whole 20 seconds on each of the 3 trails. The data was saved in excel files. When speeds of 3 mph and 4 mph were reached the attachment structure was displacing large amounts of water around it.

Figure 54: Ariel Picture of Testing Site

5.2.2 Darrieus Turbine:

Once the Savonius testing was done the boat was anchored along the edge of the channel. Two team members entered the water with 19mm wrenches (Figure 55). One team mate loosened the nuts and bolts while the other took them off. Once the bolts were removed the turbine was taken out of the top of the turbine housing. Then the Darrieus turbine was placed into the housing and the flanges were lined up. The bolts were inserted and secured with the nuts. The testing was done with the same method as with the Savonius turbine. The pontoon boat became a problem and died multiple times. A test at 2 mph and 4 mph were preformed before the team decided it was no longer safe to be on the water with the faulty boat.

Figure 55: Changing the turbines

As the team was moving into the anchorage the throttle was moving back and forth from idle to full throttle. Eventually the turbine failed, and the motor became unmanageable. The boat was then pulled to the sea wall and the turbine housing was removed and placed on the seawall. The boat was then towed to the dock by the pontoon boat being used by Wet Mobile Watts.

The Testing was stopped for the day and the boat was fixed that evening by Tim Fletcher.

5.2.3 Gorlov Turbine:

Due to the faulty boat, the Gorlov testing was delayed until Thursday July 16, 2009. The first step was placing the Gorlov turbine into our turbine housing which was done on land (Figure 56). Everything was then loaded onto the boat and we attached the structure in the channel where the testing was done, rather than put the entire structure on at the dock and risk running aground before testing began. Testing was done at 1,2, and 3 miles per hour. Four miles per hour seemed too fast and the team decided to not risk breaking the attachment structure from the large drag force.

Figure 56: turbine Housing with Gorlov Blade Installed

6. Results Using the data collector talked about previously, the team collected the following data:

Figure 57: Chart of Turbine Power by Current Velocity

6.1 Savonius Turbine

Table 1: Averaged Experimental Data for Savonius Turbine

Speed Average Voltage

Average Current

Average RPMs

Average Power

[MPH] [V] [mA]

[W] 2 11.13 50.22 39 0.56 3 13.44 60.11 61 0.81 4 13.69 61.58 63 0.84

With an increase in water velocity the turbine had an increase in power production. The power increased more from the speed of 2 mph to 3 mph than from 3mph to 4mph. The smaller increase could have meant the turbine was coming closer to its peak power point.

6.2 Darrieus Turbine

Table 2: Averaged Experimental Data for Darrieus Turbine

Speed Average Voltage

Average Current

Average RPMs

Average Power

[MPH] [V] [mA]

[W] 2 13.91 62.73 79 0.87 3 14.71 65.67 88 0.97

During the testing the pulsing was very noticeable. Team members could feel the boat moving with the pulses and see the attachment structure moving at the same time.

It was difficult to get the Darrieus turbine to start spinning. This experimental result backed the research found on this turbine previously discussed in this paper. The boat had to be at a minimum of 2 mph for the turbine to begin to spin and at times required a rapid deceleration to begin the spinning.

The turbine produced the highest amount of power. More measurements were necessary to gain conclusive results on the behavior of this turbine at multiple speeds.

Just before the boat hit 4 MPH the experiment the blades failed. A rapid increase in speed from the throttle resulted in a very rapid acceleration of the boat which the turbine could not handle. Two of the blades fractured in the center of the airfoil and one of the two broken ones ripped off of the turbine (Figure 58). A team member had to jump into the water to then retrieve the turbine blade as it floated behind the boat.

Figure 58: Broken Blade of Darrieus Turbine

6.3 Gorlov turbine

Table 3: Averaged Experimental Data for Gorlov Turbine

Speed Average Voltage

Average Current

Average "Counts"

Average Power

[MPH] [V] [mA]

[W] 1 8.00 35.56 43 0.28 2 8.50 38.73 56 0.33 3 8.92 40.12 87 0.36

The Gorlov blade did not pulsate as much as the Darrieus turbine, as expected from theory. The turbine started spinning easily at 1 mph. Once the turbine started spinning, the boat continued to run smoothly with only small amounts of pulsation in the attachment structure and the bow of the boat. This blade also did not break and had no visible damage breakage when examined after the testing.

This turbine had the lowest power production but was the smoothest running and started producing power at the lowest speed.

7. Conclusions

7.1 Airfoil Profile

The airfoil used for the Gorlov turbine, NACA 0020, was chosen because it was the same airfoil type used by Gorlov in his experiments between 1996 and 1998. This airfoil was symmetrical and did not form a large amount of lift. The Darrieus turbine used to the NACA 63(2)-015 airfoil. This airfoil created large amount of lift. During the testing the throttle on the boat was malfunctioning. While returning to the dock the boat rapidly accelerated. The rapid acceleration of the boat and fluid flow around the airfoils created too much force and fractured two of the three airfoils on the turbine in the center of the blades. The bolts on one of the blades were sheared off due to the high amount of force created by the airfoil. The team concluded that the results would have not came out as they did if the airfoils on both of the blades were the same.

7.2 Pulsing/Vibrating

While testing the Darrieus turbine large amounts of pulsation in the turbine occurred. This resulted in the bow of the pontoon shaking with the pulses. The amount of shaking increased with an increase in speed of fluid flow. The theory behind the Gorlov turbine stated that it would reduce pulsation in the turbine compared to the H-frame Darrieus style turbines (Gorlov, 1998). While testing the Gorlov the amount of pulsation was minimal and much less than Darrieus turbine.

7.3 Angle of Attack

The Gorlov and Darrieus turbines had two different angles of attack. The Darrieus was oriented 5 degrees out from its path of rotation. This varied from the Gorlov turbine blades which had no variation. This was due to limitations on time with the creation of the molds for the Gorlov Turbine. This may have also contributed to the low power output of the Gorlov turbine.

7.4 Manufacturing

The manufacturing of the Savonius turbine was not overly time consuming and fairly simple. With the blades being made out of 55 gallon barrels they were easy to cut and attach to the turbine. Both airfoil type turbines had much more complicated construction processes. Both sets of blades were made out of composite materials. The use of composites was a new field for the team. It was a near necessity to have outside consulting help to make the turbine blades strong enough to handle the forces they would be put through during our testing. The prototyping of these blades was a time consuming process. After the prototyping was complete they blades were quick and easy to produce.

8. Future Considerations

8.1. Possible Future Applications

The product designed during this project was created with the intent of versatility for many applications.

One of the most promising applications of this project is as a subsurface buoy power system. Surface floating buoys are commonly powered by solar power. However, subsurface buoys have no access to sunlight. For this reason, many subsurface buoys are powered by either a surface buoy or battery power. This device could be of great benefit to not only subsurface, but surface buoy systems as well.

This system could be applied in the coming year to the surface weather buoy built by an undergraduate Ocean Engineering team during the spring 2009 semester. This could be a viable application for this buoy if it was to be deployed in an area of very low sunlight. This would also be a good demonstration of the potential power production of this system in open ocean conditions.

These turbines can also be placed in large arrays. Multiple companies around the world are looking to deploy systems with these types of turbines into areas of large tidal flow and current movement. These types of systems have the potential to produce large amounts of power for many of the local communities centralized around these ocean resources.

8.2. Generator Improvements

The main search parameter for a generator for our project was affordability. The generator used was taken off a former senior project. The generator was not optimized for this device. In addition, previous years of use has taken a toll on the efficiency of the generator. The device would be greatly improved by installing a generator specifically optimized and chosen for this device.

8.3 Airfoil Improvements

One of the main goals of this project was to create an accurate comparison between the Gorlov Turbine and the Darrieus turbine. However, as the project progressed, design choices compromised that goal. As discussed previously, the Gorlov Turbine and the Darrieus turbine have different airfoil profiles, as well as different angle of attacks. The Gorlov Turbine should be modified and given a 5˚ and the airfoil profile defined by NACA 632-015. This would provide a more accurate comparison between turbines, as well as greatly increase the power output of the Gorlov Turbine.

Appendix A: Works Cited

Borgnakke, Claus., Sonntage, Richard (2009). Fundamentals of Thermodynamics. Hoboken,NJ: John Wiley & Sons, Ltd.

Burton, Tony., Sharpe, David ., Jenkins, Nick ., Bossanyi, Ervin (2001). Wind Energy Handbook. West Sussex, England: John Wiley & Sons, Ltd.

Darrieus, G. J. (1931). Patent No. 1835018. United States of America.

DeCoste, J., McKay, D., Robinson, B., Whitehead, S., & Wright, S. (2005). Vertical Axis Wind Turbine. Halifax: Dalhousie University, Department of Mechanical Engineering.

Gorlov, A. M. (1998). Helical Turbines for the Gulf Stream. Marine Technology and SNAME News , 175-182.

Hurst, T. (2008, June 20). Vertical Axis Turbines: The Future of Micro Wind? Retrieved April 26, 2009, from Clean Technica: http://cleantechnica.com/2008/06/20/vertical-axis-turbines-the-future-of-micro-wind-energ/

Understanding Extruded Aluminum Alloys. (n.d.). Retrieved April 26, 2009, from Alcoa: http://www.alcoa.com/adip/catalog/pdf/Extruded_Alloy_6061.pdf

Appendix B: Bill of Materials

Bill Of Materials ITEM QTY.

1-¼” Nom, Sch 40 Alum. Pipe 40 feet 1-¼” OD, 0.125” Wall Alum. Tube 12 feet 6" x 0.25" Alum. Bar 7 feet ¼” x 1” Ext. Alum. Bar 12 feet External Retaining Ring 2 unit(s) Ball Bearing Flanged Double Sealed 4 unit(s) 1/2" bolt (1.5" long) 18 unit(s) 1/2" Washers (50 Pack) 36 unit(s) 1/2" nuts (25 pack) 18 pack(s) Aluminum U-Bolt 16 unit(s) 1" Alum. Rod 24 inch(es) 3" Alum. Rod 6 inch(es) 1.25" diameter Aluminum Elbows 8 unit(s) 8" x 20"x0.25" Aluminum Sheet 2 unit(s) 2' x 4' Oak Plywood (0.25" Thick) 1 unit(s) Epoxy Resin 1 unit(s) Bike computer 1 unit(s) Latex Gloves 1 unit(s) Misc. Hardware 1 unit(s) 2" Square, 0.25" Wall Aluminum Tubing 24 feet 2" Square, 0.188" Wall Aluminum Tubing 24 feet #10-32 Aluminum Bolts (50 Pack) 1 Pack(s) #10 Aluminum washers (5 Pack) 5 Pack(s) 3/8"-24 Stainless Steel Bolts (10 Pack) 1 Pack(s) 3/8"-24 Stainless Steel Nuts (10 Pack) 1 Pack(s) 3/8" Alumiunum Washers (5 Pack) 3 Pack(s) 5/8 Aluminum Washers (5 Pack) 8 Pack(s) Fiberglass cloth 1 roll CD-to-3 Ring Binder Attachment 1 unit(s) Binder Index, 12 tabs 1 unit(s) 2”, 3-ring Binder 1 unit(s) 3M Tape Vinyl ¾”, 60 feet 1 unit(s) Dorman Zip-ties, 100 qty, 8” long 1 unit(s) Dayco 29” V-Belt 1 unit(s) #8 Stainless Steel Screws 1.5” (5 pck) 3 unit(s) Generator/Motor 1 unit(s) Waterproofing Gasket Material 1 unit(s)

Appendix C: Project Budget

See following page.

Appendix D: Schedule (Gannt Chart)

Appendix E: Hours Worked

Hours Worked

Week Of

Joshua Lappen

Travis Schramek

Geordy Smitt

1/12/09 10 10 10 1/19/09 5 5 5 1/26/09 5 5 5 2/2/09 5 5 5 2/9/09 5 5 5 2/16/09 5 5 5 2/23/09 10 10 10 3/2/09 5 5 5 3/9/09 7 7 7 3/16/09 3 4 3 3/23/09 10 10 10 3/30/09 5 5 5 4/6/09 10 10 10 4/13/09 10 10 10 4/20/09 10 10 10 4/27/09 0 0 0 5/4/09 0 0 0 5/11/09 4 4 4 5/18/09 0 0 0 5/25/09 32 32 4 6/1/09 35 35 4 6/8/09 30 30 25 6/15/09 35 35 35 6/22/09 37 37 2 6/29/09 38 38 30 7/6/09 35 35 5 7/13/09 40 40 40 7/20/09 50 50 50 Total 441 442 304

Total Hours: 1187