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Wind Instrument Testing Apparatus Project

WITAP

Team: Rob Koch

Andy Lawrence

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Background

An anemometer is a device used to measure wind

speed.

Commonly it is mounted on towers or inaccessible

places.

The data generated from these devices is used toassess the feasibility of wind power generation at that

site.

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Problem Statement

Vermont Technical College has an Anemometer Loan

Program using NRG anemometers.

The anemometers need to be checked periodicallyfor

function and calibration.

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Type of Anemometer to be Tested:

Cup Anemometer:Simplest type of anemometer

Air flow past the cups turns the spindle outputting a varying frequencysignal proportional to the wind speed

Standard models use a sensitive 4-pole magnet

Type to be calibrated in the device

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Our proposed solution is to build an airflow chamber that

can put out a steady and consistent air velocity to an open

air anemometer and save cost.

A workshop device needs to be developed with an

effective range of air flow control and data acquisition

capability to assess anemometer operation and accuracy.

Solution Statement

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System Requirements

Non-Turbulent Air Flow Output

Wind Velocity Controlled to 0.2 m/s

Air Flow Capable of 1 to 20 m/s (45mph)

Accuracy and Consensus of Measured Data Repeatability of Results

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Work so Far

Design and Build Chamber

Test General Wind Flow Capability of

System Test Specific Airflow Characteristics of

Chamber

Design and Build Mechanical Features Design and Build Electronic Control System

Test, Test, Test,

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Solution

A wind tunnel with reduced outlet for higher velocity

Powered by constant-speed 120VAC fan

Wind speed can be varied with shutters at inlet to fan

Wind speed is measured with a pitot tube connected to apressure sensor that outputs 0 to 4V DC

Wind speed is controlled by using the 0 to 4 V signal and

controlling the shutters accordingly

Shutter control system consists of a Motorola HC08microcontroller, a Reversible DC motor controller, and a

DC motor connected to the shutters.

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Test Sequence

PC HC08Pressure

Sensor

Converted

Setpoint

Value

0 to4v

Signal

Time Delay

Setpoint = VelocityYes No

Acquire Data

From Anemometerand Sensor

Adjust

DamperNew Setpoint

Compare

Data

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HC08RS232

DifferentialPressure

Sensor

H Bridge

Motor Controller

5V GND 0.25-4V

PWM Signal

A/D

.

.

Damper Motor

+ -

Dampers

Setpoint

Entry

Fan

Dampers

Chamber

PC

Wind Outlet

Pitot Tube

Air hoses to sensor

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Outlet

= 2g(Pt-Ps)/ General Equation

g = acceleration of gravity, = specific weight of air= Pv(1.289)2 Pv (Pa), (m/s)= Pv(4005)2 Pv (inH2O), (ft/min)

Pt = Total Pressure

Ps = Static Pressure

Pv = Velocity Pressure = (Pt-Ps)

= velocity

Pt

Ps

Measuring Air Velocity using Velocity PressureVelocity Pressure uses the differential pressure

in the output to determine velocity

Pt tapPs tap

Manometer

Chamber

DampersFan

Simulated

Wind

Air Flow

Pitot-Static Tube

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Pitot Tube Function

When a moving fluid is caused to stop because it encounters a stationary object, apressure is created at that point that is greater than the pressure in the fluid stream.

The magnitude of this increased pressure is related to the velocity of the moving fluid.

The pitot tube measures the stagnation pressure due to the deceleration of the flowingfluid.

Stagnation pressure

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Costs

Device Needed Device Used Quantity Unit cost Balance Project Cost

Dayton Duct Fan 4TM81 1 $813.50 $813.50 FreeMotor controller H bridge 1 $30.00 $30.00 FreeMicro controller HC08 1 $53.14 $53.14 FreeChamber MDF Box 1 $30.00 $30.00 $30.00

Pressure sensor Sensirion 1 $91.21 $91.21 $91.21Manometer Dwyer 1 $64.00 $64.00 FreeManometer oil Dwyer 1 $10.08 $10.08 $10.08Pitot-static tube Dwyer 1 $48.00 $48.00 $48.00Damper Operator Denso motor 1 ? free freeDamper Unit Homebuilt 1 $20.00 $20.00 $20.00miscellaneous hardware n/a n/a n/a $10.00

$1,139.93 $179.29

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Time breakdown

J8-12 J15-19 J22-26 J29-F2 F5-9 F19-23 F26-M2 M5-9 M12-16 M19-23 A2-6 A9-13 A16-20 A23-27

Task Week 1 W eek 2 W eek 3 W eek 4 W eek 5 W eek 6 W eek 7 W eek 8 W eek9 W eek 10 W eek 11 W eek 12 W eek 13 W eek 14

Chamber

Design and PlanResearch Materials

Cut Materials

Assemble Materials Install fan &motor

Install outlet duct

Install instrument

boom

Motors

Research Motor

Characteristics

Control Electronics

Research Controllers

Research Actuators

Research Sensors

Build Control System

Test Control System

Software

Determine Function

of Software

Write/ Load Software

Test Software

Website

Edit Website

Reports and

Documentation

Presentations

Testing

air flow measure

air flow calculations

Test sensors

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Questions?