9865284-MEC-2600-Lab-Manual-II

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DEPARTMENT OF MECHANICAL ENGINEERING

KULLIYYAH OF ENGINEERING

INTERNATIONAL ISLAMIC UNIVERSITY

MALAYSIA

FLUID MECHANICS

LAB MANUAL

MEC 2600

MEC 2700

January 2008

Syed Noh Syed Abu Bakar/ Sanisah Saharin

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TABLE OF CONTENTS ITEMS PAGES ======================================================================== Laboratory & Reports: An Overview 3

Guidelines for Laboratory Report (Lab workbook) Writing 4

Guidelines for Final Report Writing 5

Experiment # 1: FLOW RATE MEASUREMENT 8

Experiment # 2: FRICTION LOSSES 10

Experiment # 3: IMPACT OF JET 12

Experiment # 4: REYNOLDS OSBORNE EXPERIMENT 14

Experiment # 5: PUMPS IN SERIES & PARALLEL 15

References 16

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LABORATORY & REPORTS: AN OVERVIEW

All experiments in the Fluid Mechanics Laboratory require either a laboratory report (lab

workbook) or a final laboratory report for selective experiments, unless it is stated otherwise. The

reports should be simple and clearly written. Laboratory reports (lab workbook) are due after all

of the experiments are performed, unless it is stated otherwise. Final reports should be submitted

a week after the experiment’s day, unless it is stated otherwise. Any late submission will not be

entertained, unless there are concrete and unavoidable reasons.

The laboratory reports (lab workbook) should be in hand writing and any graphs needed should be drawn in either an appropriate graph paper or drawn using EXCEL, whichever suitable.

However, for final laboratory reports, it should be computer-generated and any graphs should be

drawn using EXCEL.

The final laboratory reports should be submitted to the instructor directly or at the instructor’s

office. The pre-lab questions in this lab manual should be answered and submitted during the first 5

minutes before you start your experiment accordingly.

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GUIDELINES FOR LABORATORY REPORT WRITING (Lab

Workbook)

All experiments in the Fluid Mechanics Laboratory require a laboratory report unless specified otherwise. The report should be written in such a way that anyone can understand and convinced with

what the experimenter will do in the experiments. The following formats are proposed as a guide. The

students may add or delete sections as needed for each specific experiment in order to obtain a logical,

self-contained document.

Title page Specify the experiment’s number and its title. Include names of all experimenters, experimenters’

matric numbers, experimenter’s programme (Aerospace or Automotive) and dates when experiments

were carried out

Objectives The objectives are a clear concise statement explaining the purpose of the experiment. This is one of the most important parts of the laboratory report because everything included in the report must

somehow relate to the stated object. The objectives can be as short as one sentence and it is usually

written in the past tense.

However, for this course you just have to copy from lab manual and rewrite it in your reports.

Introduction Indicate what the overall plan of the experiment is: what will be done and how (the procedures),

which variables will be manipulated and measured. Clearly indicate what the reader should expect to

find in each of the subsequent sections.

Results Include all tables and graphs that document your final results. Include all relevant information so that

you can later refer to these figures in the Discussion section to support your conclusions.

Sample Calculations Give one example of each calculation that leads to a result reported in the document. Include one

calculation for each figure or table reported in the Results section.

Discussion and Conclusion This section should give an interpretation of the results explaining how the object of the experiment

was accomplished. Note down and discuss briefly any observations and trend that you could possibly

deduce from your results.

Pre-lab Questions Answer the problems at ‘Pre-lab Questions’ section in this lab report and submit during the 5 minutes

of commencing your experiment accordingly.

References List all the literature sources that are cited in the report. You may refer this lab manual References for

format reference.

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GUIDELINES FOR FINAL REPORT WRITING

There will be only two of the experiments from the Fluid Mechanics Laboratory require a final laboratory report unless specified otherwise. The report should be written in such a way that anyone

could duplicate the performed experiment and find the same results as the originator. The reports

should be simple and clearly written.

The report should communicate several ideas to the reader. First, the report should be neatly done.

The experimenter is in effect trying to convince the reader that the experiment was performed in a

straightforward manner with great care and with full attention to detail. A poorly written report might

instead lead the reader to think that just as little care went into performing the experiment. Second,

the report should be well organized. The reader should be able to easily follow each step discussed in the text. Third, the report should contain accurate results. This will require checking and rechecking

the calculations until accuracy can be guaranteed. Fourth, the report should be free of spelling and

grammatical errors. The following format is to be used for formal Laboratory Reports:

Title page Specify the experiment’s number and its title. Include names of all experimenters, experimenters’

matric numbers, experimenter’s programme (Aerospace or Automotive), date of submission, and

dates when experiments were carried out. Refer to Appendix A for the example of this title page.

Table of Contents Lists each major section and subsection and their page numbers. You may refer this lab manual Table

of Contents as a format reference.

Objectives The objectives are a clear concise statement explaining the purpose of the experiment. The objectives

serve as a guide to the results. This is one of the most important parts of the laboratory report because everything included in the report must somehow relate to the stated objectives. The objectives can be

as short as one sentence and it is usually written in the past tense. Do not exceed one page.

However, for this course you just have to copy from lab manual and rewrite it in your reports.

Abstract/Introduction Summarize the important results. The abstract must be self-contained: do not refer to figures and tables located in other sections of the report. Do not include tables, figures, and equations, unless

absolutely necessary. Do not assume that the reader will unambiguously identify undefined symbols.

Be precise and succinct. Do not exceed one page. The Abstract should be written with great care because it is a most important part of the Final Report and will have a very large impact on the

grade assigned to the work.

Procedure The procedure section should contain a schematic drawing of the experimental setup including all

equipment used in a parts list with manufacturer serial numbers, if any. Show the function of each part

when necessary for clarity. Outline exactly step-by-step how the experiment was performed as there is

someone desires to duplicate it. If it cannot be duplicated, the experiment shows nothing.

Results Include all tables and graphs that document your final results. Include all relevant information so that

you can later refer to these figures in the Discussion section to support your conclusions. If possible, present the results in the same order that you listed the objectives. Do not discuss the significance of

the results. Include only final results that satisfy the objectives of the experiment; lengthier tables and

intermediate figures should be included in the Appendix. Introduce the reader to each figure and table

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with a brief paragraph indicating what variables are plotted or tabulated. Each figure and table must

have a unique number and a title or caption.

Sample Calculations Give one example of each calculation that leads to a result reported in the document. Include one calculation for each figure or table reported in the Results section. Introduce each calculation with a

brief paragraph indicating to the reader which specific point in a figure or entry in a table is being

calculated. These calculations are samples only and must be annotated. Extensive calculations should be included in the Appendix; the Sample Calculations section can then include appropriate references

to the Appendix.

Discussion and Conclusion This section should give an interpretation of the results explaining how the objectives of the

experiment were accomplished. Any significant observations should be noted down and discussed.

Any graphs or other relevant results should be discussed in terms of trend, importance and

other significant information that could be deduced. If any analytical expression is to be verified,

calculate % error and account for the sources. (% error – An analysis expressing how favourably the

empirical data approximate theoretical information. There are many ways to find % error, but one method is introduced here for consistency. Take the difference between the empirical and theoretical

results and divide by the theoretical result. Multiplying by 100% gives the % error. You may compose

your own error analysis as long as your method is clearly defined.) Discuss this experiment with

respect to its faults as well as its strong points. Suggest extensions of the experiment and

improvements. Also recommend any changes necessary to better accomplish the objectives. Use the

available theory to explain why the relevant variables behaved in the observed fashion.

Appendix (1) Original data sheet. This original data sheet should be approved by instructor(s) during experiment day.

(2) Calibration curves of instruments which were used in the performance of the experiment. Include

manufacturer of the instrument, model and serial numbers. Calibration curves will usually be supplied by the instructor.

(3) Bibliography listing all references used.

Short Form Report Format Often the experiment requires not a formal report but an informal report. An informal report includes

the Title Page, Object, Procedure, Results, and Conclusions. Other portions may be added at the

discretion of the instructor or the writer. Another alternative report form consists of a Title Page, an

Introduction (made up of shortened versions of Object, Theory, and Procedure) Results, and

Conclusion and Discussion. This form might be used when a detailed theory section would be too

long.

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Graphs In engineering laboratory reports, one of the methods to represent the results is graph. The graph

sometimes summarized the results. An acceptable graph has several features. Some of the important

features are as following. • Axis labels defined with symbols and units.

• Each line is identified using a legend.

• Data points are identified with a symbol: “x” on the Qac line to denote data points obtained by

experiment.

• Data points are identified with a symbol: “o” on the Qth line to denote data points obtained by

theoretical.

• Nothing is drawn freehand.

• Should have number and title; e.g. Fig. E1.1 Volumetric flow rate, Q vs. head drop, ∆h. Title is

descriptive, rather than something like Q vs ∆h

• For non-computer generated graph, a graph paper must be used.

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EXPERIMENT # 1

FLOW RATE MEASUREMENT OBJECTIVES The objectives of the experiment are:

1. To show the measurement of flow rate

2. To show the application of Bernoulli equation in flow rate measurement 3. To show effect of minor losses and its modification in flow rate measurement

4. To demonstrate piezometer as a method to measure pressure

LEARNING OUTCOMES It is expected by completing the experiment, the students will be able:

1. To determine flow rate by using orifice meter, Venturi meter and rotameter 2. To explain how to calculate ideal flow rate by using Bernoulli equation

3. To determine the correction factor for by using an elbow and a sudden expansion

4. To measure pressure by using piezometer

THEORY/BACKGROUND {More in textbook [1] section 5-4 and 8-8} There are various ways of measuring volumetric flow rate. Some flow meters measure the flow rate

directly by discharging and recharging a measuring chamber of known volume continuously and keeping

track of the number of discharges per unit time. However, most flow meters measure the flow rate

indirectly – they measure the average velocity V or a quantity related to average velocity such as pressure

and drag, and determine volume flow rate, Q from Q = AV, where A is cross sectional area of flow.

Obstruction Flow Meters: Venturi Meter and Orifice Meter

One way to measure flow rate is to put obstruction in a pipe flow such as a throat (Venturi Meter) and

simple obstruction that reduced the cross sectional area (Orifice Meter).

Theoretical ideas behind these flow meters are the conservation of mass and the Bernoulli equation. From

conservation of mass we know that reduce of cross sectional area will contribute to an increase of velocity. Thus, from Bernoulli equation, this will lead to a decrease of static pressure. These kinds of flow meters

did not measure the flow rate or velocity directly but it measures the drop of static pressure. Then the velocity can be calculated from Bernoulli equation and conservation of mass.

The same idea can be applied for sudden expansion and elbow meter.

Rotameter

Rotameter is also known as variable-area flow meter or float meter. A rotameter consists of a vertical tapered conical transparent tube made of glass or plastic with a float inside that is free to move. As fluid

flows through tapered tube, the float rises within the tube to a location where the float weight, drag force

and buoyancy force are balance each other and the net force acting on the float is zero. The flow rate is

determined by simply matching the position of the float against the graduated flow scale outside the

tapered transparent tube.

Coefficient of Discharge

For rotameter the flow rate can be read directly from scale at tapered tube. However, for obstruction flow

meter, we need to consider a loss due to viscous (frictional) effects. As we know the Bernoulli equation did

not include the viscous effects. The for, any calculation that calculated from the conservation of mass and

Bernoulli equation is an ideal volumetric flow rate, not an actual one. Thus, to determine an actual

volumetric flow rate a correction factor need to be introduced to the ideal flow rate equation. This

correction factor is called as coefficient of discharge. The coefficient of discharge can be defined as the ratio of actual flow rate to the ideal flow rate.

Loss coefficient

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Due to viscous effects, there are losses at the obstruction. The losses at the obstruction can be considered

as minor losses. If the pressure drop and average velocity is known, then the loss coefficient can be

determined since the pressure drop is proportional to velocity.

This experiment is to demonstrate flow rate measurements.

For Orifice meter, Venturi meter,

1. Measure pressure drop (in term of head) as a function of valve opening. 2. Determine ideal flow rate and actual flow rate.

3. Determine Reynolds number

4. Determine coefficient of discharge, Cd

5. Prepare the following graph

a. On the same set of axes, plot actual volume flow rate vs. pressure head drop and ideal

flow rate vs. pressure head drop with flow rate on the vertical axis for obstruction flow

meter

b. Plot actual volumetric flow rate vs. ideal flow rate for Rotameter

c. Plot coefficient of discharge vs. Reynolds number on log-log grid for obstruction flow meter

For Elbow meter and Sudden expansion:

6. Measure pressure drop (in term of head) as a function of valve opening.

7. Determine the loss coefficient by plotting graph pressure head drop vs. V2

/2g (where V is

average velocity and g is gravitational acceleration)

8. Compare the calculated loss coefficient with the manufacturers published loss coefficient for

Orifice meter and Venturi meter.

EQUIPMENT: Hydraulic Bench

Flow Meter Apparatus

PRE-LAB QUESTIONS

1. Explain briefly the following terms:

i. Pressure Head

ii. Velocity Head

iii. Elevation Head

2. Define Loss Coefficient

3. Define Coefficient of Discharge and what its significance in flow rate measurement.

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EXPERIMENT #2

FRICTION LOSSES OBJECTIVES The objectives of the experiment are:

1. To modify Bernoulli equation

2. To show one of the restriction in application of Bernoulli equation 3. To investigate pressure loss due to friction


1. To apply energy equation (integral form) to estimate the friction losses in a given pipeline

situation 2. To determine friction losses and pressure drop due to friction

THEORY/BACKGROUND Bernoulli equation may be the most used and abused in fluid mechanics. Therefore, it is important to

know the restriction of the Bernoulli equation. This experiment is meant to show one of the Bernoulli

equation restrictions, which is the effect of viscosity. Viscosity, the tendency of a fluid to stick to

another fluid or any boundary, is one of the fluid properties. Viscous effect only can be neglect when

the viscous force is small compared to other force such as an inertia force. Friction effect is due to this

property (viscosity). If viscous effect is not negligible, then the frictional effect also not negligible.

The first part of this experiment is to show about this effect and to modify the Bernoulli equation so

that it can be use in a viscous flow.

One of the most important properties in pipe design as well as pump selection for pipe network is the

pressure drop. Pressure drop occurs because of the friction occur at the wall of the pipe as well as because of elbows, bends and fittings that exist in a piping system. The study of pressure drop is the

purpose of the second part of the experiment.

First Part: Modification of Bernoulli Equation {More in textbook [1] section 5-4 and 5-7}

There is several ways to derived Bernoulli equation. One of it is by using First Law of

Thermodynamics or also known in Fluid Mechanics as Energy equation. By applying an appropriate assumptions and considerations to Energy equation, we will obtain the Bernoulli equation. Thus, in

other word we can say that the Bernoulli equation is also a statement of energy that fluid carries.

The work done on a particle by all forces acting on the particle is equal to the change of the kinetic

energy of the particle is what the Bernoulli equation express in mathematical terms.

For flow in a close conduit, the Bernoulli equation says that the energy should equal to a constant at

any point in the length of the conduit.

This experiment is to check this statement and modify the statement if it is incorrect. For that purpose,

draw Hydraulic Grade Line and Energy Grade Line. Determine whether there are effects of the

Reynolds number or the volumetric flow rate to HGL and EGL.


Bernoulli Experiment’s Apparatus

Second Part: Friction Losses in Straight Pipes, Bends and Elbows

{More in textbook [1] section 5-6 until 5-7, 8-4, and 8-6} A pipe system usually consists of straight pipes, bends, elbows, valve and fittings. The existent of

these parts will contribute to a loss (due to friction). A loss will lead to a pressure drop. In pump

selections, there are needs to know about the pressure drop.

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A loss in overall piping system is called major loss while loss in bends, elbows, valve and fitting is

called as minor loss.

This experiment is to study about the friction losses in straight pipes, bends and elbows.

For all studies, measure the losses as a function of volumetric flow rate.

For losses in straight pipes (7mm and 10mm diameter pipe),

1. Calculate the friction factor from Darcy-Weisbach Equation

2. Graph the friction factor as a function of Reynolds number, drawn in log-log grid.

3. Compare to Moody diagram

For losses in pipe consist of bends or elbows:

1. Determine the equivalent length (Use Table E1.1) 2. Determine friction factor (Use modified Bernoulli equation in term of head where head loss

consist of loss from straight and bends or elbows are considered)

3. Determine loss coefficient (Weisbach equation) 4. Compare the loss coefficient that have been determined with loss coefficient calculated from

Table E1.1

5. Determine if the loss coefficient varies with flow rate or Reynolds number.

The surface roughness is 0.0015 mm.

R is radius of bend; D is diameter of pipe; f is friction factor; Le is equivalent length; K

b is loss coefficient

Table E1.1


10 mm diameter straight pipe

7 mm diameter straight pipe

Inlet and Outlet head

Pipe with 4 bends

Pipe with 4 elbows

PRE-LAB QUESTIONS

1. Explain the phenomena that occur at a bend that lead to a loss.

2. State Darcy-Weisbach Equation for head loss, hL..

3. What is minor loss?

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EXPERIMENT # 3

IMPACT OF JET OBJECTIVES The objectives of the experiment is to compare the momentum in fluid jet with force generated when

it strikes a flat plate, a 120° plate, a conical object and a hemispherical cup


1. To explain conservation of linear momentum

2. To apply conservation of linear momentum to estimate force exerted by an object from a fluid

jet

THEORY/BACKGROUND {More in textbook [1] section 6-1 until 6-4} A jet is a stream issuing from an orifice, nozzle or tube. It is not enclosed by solid boundary walls but is

surrounded by a fluid whose velocity is less than its own. The two fluids may be different or they may be

of the same kind.

From conservation of linear momentum, we know that if a jet of fluid striking an object, will exerts a force

on that object. Theoretically, the force can be estimated from conservation of linear momentum in integral

form (to get an average value) or in differential form (i.e. Euler’s equation or Navier Stokes equation).

Experimentally, the force can be determined if we connect the object to a spring balance or scale.

For this experiment, 1. Determine (For two size of nozzle)

a. Volumetric flow rate

b. Velocity of jet

c. Theoretical and actual resultant force generated when jet strikes a flat plate, a 120° plate,

a conical object and a hemispherical cup – the theoretically resultant force is found by use of an equation derived by applying conservation of linear momentum to a control

volume about the plate/object 2. Plot, on the same set of axes, graph of actual force vs. volumetric flow rate and theoretical force vs.

volumetric flow rate with volumetric flow rate on the horizontal axis.

EQUIPMENTS: Hydraulic Bench

Impact of Jet Apparatus

PRECAUTIONS ON HANDLING EQUIPMENT

1. Make sure the control valve is close completely every time before the pump is switch on. This is to avoid intrusion of air into the pump. Entrapped air can reduced the force exerted by the jet thus reducing it efficiency.

2. Reading on PU tube should be on the water meniscus to avoid parallax error.

3. When measuring the flow rate, volume difference should be taken at least 10 liters for a more accurate reading. For high flow rate, start measuring only when the water at the measuring tank

reaches the second level of the compartment. This is to ensure a steady increment of water level in

the PU tube. 4. It is important to drain all water from the apparatus when not in use. The apparatus should be stored

properly to prevent damage.

5. The apparatus should not be exposed to any shock and stresses.

6. Always run the experiment after fully understands the unit and procedures.

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PRE-LAB QUESTIONS

1. What is the ‘conservation of momentum?

2. State the equation of flow rate in terms of velocity and cross sectional area.

3. What is the effect of nozzle diameter to the velocity of the water?

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EXPERIMENT # 4

REYNOLDS OSBORNE EXPERIMENT OBJECTIVES The objectives of the experiment are:

1. To demonstrate laminar, transition and turbulent flow

2. To introduce Reynolds number to classify laminar, transition and turbulent flow


1. To describe laminar, transition and turbulent flow

2. To determine critical Reynolds number for laminar, transition and turbulent flow

THEORY/BACKGROUND {More in textbook [1] section 8-2} Fluid flow can be classified to three regimes which is laminar, transitional and turbulent regime. Laminar

regime is a regime where the flow is characterized by smooth streamlines and highly ordered motion.

Turbulent is a regime where flow is characterized by velocity fluctuations and highly disordered motion.

Transitional regime is where the flow fluctuates between laminar and turbulent before it becomes fully turbulent.

The transitional from laminar to turbulent flow depends on geometry, surface roughness, flow velocity,

surface temperature, and type of fluid. However, Osborne Reynolds discovered that the flow regime

mainly depends on the ratio of inertial forces to viscous forces. This ratio is what we called as Reynolds

number.

At small or moderate Reynolds numbers the viscous forces are large enough to suppress theses fluctuations

and to keep the fluid “in line”. Thus, the flow is streamlined and in ordered motion. However, at large

Reynolds numbers, the inertial forces, which are proportional to the fluid density and the square of the

fluid velocity, are large relative to the viscous force. As the results, the viscous force cannot prevent the

random and rapid fluctuations of the fluid. Thus, the flow will be in disordered motion.

The boundary of Reynolds number for laminar, transitional and turbulent regime varies by geometries and flow condition. For example, flow in a circular pipe is laminar for Reynolds number less than 2300,

turbulent for Reynolds number larger than 4000 and transitional in between. However, we will have other boundaries if the pipe cross sectional area is a square.

[This part was taken with some modification from textbook Fluid Mechanics: Fundamentals and Applications; Yunus A. Cengel and John M. Cimbala; McGraw Hill, 2006.]

This experiment is to visualize the laminar, transitional and turbulent flow in a pipe and to determine the

boundary of Reynolds number for flow in the pipe.

First by controlling the flow rate, establish the laminar flow. Then by slowly increase the flow rate

observes what happened to the dye streak. Record the flow pattern change and its volumetric flow rate

reading. Determine the boundary of Reynolds number for laminar, transitional and turbulent regime.


Reynolds Experiment Apparatus

PRE-LAB QUESTIONS

1. What is Reynolds Number?

2. Explain what is the meaning is if one say ‘The flow has low Reynolds Number?

3. Draw velocity profile for fully developed turbulent flow.

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EXPERIMENT # 5

PUMPS IN SERIES & PARALLEL OBJECTIVES The objectives of the experiment are: 1. To demonstrate pump performance when connected in series and parallel

2. To show shut off point of pump in series and parallel


1. To estimate power requirement for a pump as a function of its throughput, pressure increase and

efficiency

2. To analyze pump network for pipelines operating under pressure

THEORY/BACKGROUND {More in textbook [1] section 14-2} In selecting a pump fro a given situation, we have a variety of pumps to choose among. The manufacturers

provide the pump performance information such as the pump performance curves. The engineer’s task is to

the pump or pumps that best fits in with the system characteristics.

One of the considerations in fulfilling a system characteristic is whether to combine a pump in one system

or not. The combination may be in parallel or series.

By examining pump performance curve for pumps in series and pumps in parallel, we easily can say that the pumps in series tend to increase head but pumps in parallel tend to increase capacity.

For this experiment,

1. Determine:

a. Average velocity of the fluid flow

b. Volumetric flow rate

c. Required net head by solving energy equation

d. Pump efficiency

2. Plot on the same set of axes the graph of available net head, pump efficiency and required net head as a function of capacity (volumetric flow rate).

3. From the graph, determine (if possible)

a. Shut off head for each pump

b. Free delivery

c. Best efficiency point

d. Operating point

EQUIPMENT Pump in Series and Parallel Apparatus

PRECAUTIONS ON HANDLING EQUIPMENT

1. Never operate the pumps when there is no liquid in the pipeline. It will cause serious damage to the pumps.

2. Do not operate pump above and below its limit operation as given below:

PRE-LAB QUESTIONS

1. Define shut off head.

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2. What will happen to the total flow rate (capacity) if you put two similar pumps in parallel

arrangement?

3. What is the meaning of available head?

REFERENCES [1] Yunus A. Cengel and John M. Cimbala, Fluid Mechanics: Fundamentals and Applications,

McGraw-Hill, 2006. [2] Bruce R. Munson, Donald F. Young and Theodore H. Okiishi, Fundamentals of Fluid Mechanics,

5th

ed., Wiley Asia Student Edition, 2006.

[3] Clayton T. Crowe, Donald F. Elger and John A. Roberson, Engineering Fluid Mechanics, 8th

ed., Wiley, 2005

[4] E. John Finnemore and Joseph B. Franzini, Fluid Mechanics with Engineering Applications, 10th

ed., International Edition, McGraw Hill, 2006.

[5] Robert W. Fox and Alan T. McDonald, Introduction to Fluid Mechanics, 5th

ed., Wiley.

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9865284-MEC-2600-Lab-Manual-II