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Wind Tunnel Project

09/28/2016 10:37 PM

Hi everyone,
I am working on a Wind Tunnel and I have a hardware to modify from.
I have no clue about sensors and I need sensors to measure Airflow, Temperature and Pressure distribution in the Wind Tunnel, the equipments have to be capable of data logging to the computer using LabView software to run the system, an existing hardware of what I have as shown,
any expert please advise.

And also the test section, how do I fit the sensors inside????

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#1

Re: Wind tunnel project

09/28/2016 11:03 PM
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#2

Re: Wind tunnel project

09/28/2016 11:04 PM

Welcome to CR4

Is this a school project? You need to advance you education in fluid dynamics. Here's a →link← for sensors And a →link← for fluid dynamics. You got some studying to do. You might also invest some time on internet research too.

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#3

Re: Wind tunnel project

09/28/2016 11:16 PM

Is that a solid wall or an air filter opposite your fan? If it's solid, you won't have much of a wind tunnel effect and no venturi effect either.

Couple nice links there lyn.

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#4
In reply to #3

Re: Wind tunnel project

09/28/2016 11:20 PM

Same to you!

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#5

Re: Wind tunnel project

09/29/2016 12:16 AM

Your blower should have the CFM's on it, or from the manufacturer....Are you going to vary the speed via controller?

I would just set a portable weather station right at the intake....

https://www.amazon.com/AcuRite-01036-Weather-Station-Monitoring/dp/B00FWSP3UC

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#6
In reply to #3

Re: Wind tunnel project

09/29/2016 12:37 AM

It is a wall made up of circular straws to streamline the airflow :)

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#7
In reply to #6

Re: Wind tunnel project

09/29/2016 12:55 AM

I was just curious

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#8
In reply to #6

Re: Wind tunnel project

09/29/2016 1:18 AM

Interesting. Good idea.

What is your budget?

Instruments with digital outputs are more expensive than simple ones.

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#9

Re: Wind tunnel project

09/29/2016 2:48 AM

Hi, we are also planning to build a wind tunnel for testing our VAWTs. Can please share dimensions and Blower capacity, etc? our web site: https://www.windstream-inc.com/

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#10
In reply to #6

Re: Wind tunnel project

09/29/2016 8:54 AM

The wind tunnel at NASA Glen Research Center had a wall of drinking straws in it used to create laminar flow. High tech using a low tech solution.

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#11
In reply to #8

Re: Wind tunnel project

09/29/2016 9:23 AM

I have a budget of aroun 500USD, I don't really know which sensors I can buy for Wind speed and temperature, plus how do I fit it.

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#12

Re: Wind Tunnel Project

09/29/2016 10:33 AM

Here's is a meter to test your air flow. it's eat up your budget. You can shop around ebay and such.

But it looks like your pitot tube should point to your source.

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#13
In reply to #12

Re: Wind Tunnel Project

09/29/2016 11:08 AM

Can this meter connect to a high speed data logger? Because I need to run the wind tunnel solely through LabView software.

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#14
In reply to #13

Re: Wind Tunnel Project

09/29/2016 11:15 AM

Here's the product data sheet, It has a USB port, but that also could be for upgrading software.

Have to see how (format) it is exported.

Simultaneous display of Pressure, Air Velocity or Air Flow plus Temperature

  • ± 0.7252psi range
  • 5 selectable units of pressure measurement
  • Max/Min/Avg recording and Relative time stamp
  • Data hold and Auto power off functions
  • Large LCD display with backlighting
  • Zero function for offset correction or measurement
  • Stoer/Recall up to 99 readings in each mode
  • USB port includes software
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#15
In reply to #11

Re: Wind tunnel project

09/29/2016 1:59 PM

A Pitot Tube and something to measure differential pressure is all that you need, Bwana.

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#16
In reply to #6

Re: Wind tunnel project

09/29/2016 2:08 PM

The distribution of blue and green don't seem to be as uniform as they should be. Good job on the yellow and red.

You can probably find DIY people measuring about anything when you add "Arduino project" or "Arduino sketch" to the Google search term. In these projects you will often find sources for low cost sensors and useful but simple interface circuits. They might not be initially compatible with your hardware but modifying them should be easy.

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#17
In reply to #15

Re: Wind tunnel project

09/29/2016 7:58 PM

Pitot tube give me the Delta P, I still need temperature and velocity data :)

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#18
In reply to #16

Re: Wind tunnel project

09/29/2016 8:00 PM

Do you have links to the cheap sensors?

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#19

Re: Wind Tunnel Project

09/29/2016 9:19 PM

Some info:

https://theses.lib.vt.edu/theses/available/etd-112299-194052/unrestricted/Chap_02_appparatus.pdf

You didn't say what you are going to use your wind tunnel for. If you are designing airplanes or other vehicles, you might need force sensors to measure lift and drag. All sensors need to disturb the airflow as little as possible.

Another idea is to introduce smoke into the airstream. This will give a visual representation of the stream lines.

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#20
In reply to #16

Re: Wind tunnel project

09/29/2016 9:44 PM

"The distribution of blue and green don't seem to be as uniform as they should be. Good job on the yellow and red."

Psychiatrists have a treatment for this, I'm told.

Do you iron your socks and underwear too?

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#21
In reply to #20

Re: Wind tunnel project

09/30/2016 7:17 AM

354... yes there are 354, 354 straws, 354 straws... yes... 354.

3 hours till people's court, 5:00 Judge Wapner comes on, I don't want to miss Wapner.....

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#22
In reply to #17

Re: Wind tunnel project

09/30/2016 1:40 PM

Buy your self an Arduino card, some cheap Chinese digital temperature sensors for the digital inputs, and put a couple of differential pressure sensors on the analog (0-5 V), then attach the pressure sensor fittings to the Pitot tubes.

Flow = Area x velocity

Velocity = K x dP

where K is apparatus constant for the Pitot tube, and dP is the pressure differential.

There ya go.

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#23
In reply to #18

Re: Wind tunnel project

09/30/2016 1:42 PM

Hi WTB,

For sensors:

https://www.adafruit.com/category/35

There are lots of other places with similar - try Amazon.

Also, the ΔP obtained from a pitot tube DOES give you velocity:

from ΔP=(1/2)ρν2

Solving for v gives:

ν=sqrt(2ΔP/ρ)

where:

ΔP = differential pressure, Pa

ρ = density of the flow medium, kg/m3

and v = velocity, m/s

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#24
In reply to #18

Re: Wind tunnel project

09/30/2016 1:49 PM

Search them on Amazon. Base your pressure sensor selection on the appropriate pressure range of your Pitot tubes. For this part: MPX5500DP, there are SIP-6 connections, so you need a connector also. It also has 2 ports. The one on the side of the sensor with the lettering is the pressure side, and the other is the vacuum side.

I suspect you will need the vacuum side, but this depends on Pitot tube design, velocity range expected, etc.

If you were looking at low velocity, I would have suggested a thermal sensor, such as a test resistor with upstream and downstream temperature readings, but that gets slightly complicated in that humidity changes the heat capacity of the air flow.

If you can determine (1) air flow at one point axially, and find this point to represent the entire flow cross section, you can easily calculate air flow at any point in your system, within limits due to perturbations introduced by your model/supports.

Wouldn't it be nice to have micro-sensors for flow near test surfaces....hmmm.

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#25
In reply to #21

Re: Wind tunnel project

09/30/2016 1:49 PM

Easy, Rainman. Don't get too excited.

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#26
In reply to #23

Re: Wind tunnel project

09/30/2016 1:50 PM

Does this not mean he has to compensate for changes in temperature, ambient pressure, and humidity? I think it definitely requires that for accurate work.

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#27
In reply to #26

Re: Wind tunnel project

09/30/2016 1:53 PM

Depends on the accuracy and resolution required, which we don't know.

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#28
In reply to #13

Re: Wind Tunnel Project

09/30/2016 1:57 PM

Is LabView some sort of course requirement?

You need to then select your sensors based on input requirement to the data-logger that will be running interfaced with LabView.

It is possible with Arduino sketches to have the data output in CSM format, so that it will directly import to Excel spreadsheet, also.

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#29
In reply to #25

Re: Wind tunnel project

09/30/2016 2:05 PM

ok Charlie, Charlie Babbitt

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#30
In reply to #17

Re: Wind tunnel project

09/30/2016 2:05 PM

Velocity comes from the differential pressure, and you should know that already.

How else do you obtain airspeed in an aeroplane?

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#31
In reply to #10

Re: Wind tunnel project

09/30/2016 2:08 PM

It doesn't create laminar flow in a fluid dynamics domain, as the Reynolds Number is so high. What it does is flow straightening. That's different.

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#32
In reply to #31

Re: Wind tunnel project

09/30/2016 3:22 PM

little off topic, but here's a cool video of laminar flow, my girlfriend found it.

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#33
In reply to #26

Re: Wind tunnel project

09/30/2016 3:58 PM

Yes, in the sense that ρ = f(T, RH), but since the pressure read by the Pitot is actually a difference between the static and dynamic pressures, the ambient pressure is "cancelled out".

The thing to remember here is that you are still only getting a single velocity value for each measurement point. To characterize the velocity profile of the chamber, a series of single point measurements must be taken according to a prescribed pattern known as traversing.

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#34

Re: Wind Tunnel Project

09/30/2016 11:03 PM

If you are poor boying it you might consider measuring the voltage generated by small wind driven fans on DC motors or a venturi with a water U-tube manometer. Up front, I think you need a set of vanes in the air stream to straighten the fan vortex. There is a small air speed instrument used by amature sailors. Look at West Marine.

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#35
In reply to #30

Re: Wind tunnel project

10/01/2016 12:17 AM
            Just stick this out the window.

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#36

Re: Wind Tunnel Project

10/01/2016 2:40 AM
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#37
In reply to #34

Re: Wind Tunnel Project

10/01/2016 12:01 PM

I'm thinking of getting a hot wired anemometer which can link to my Dewetron DEWE-2520 DAQ data logger, its simpler right?

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#38

Re: Wind Tunnel Project

10/02/2016 2:54 AM

Does anyone know where to place a hot wired anemometer in the test section? And how to measure the temperature difference of the test piece?

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#39
In reply to #14

Re: Wind Tunnel Project

10/02/2016 11:15 PM

Do you know where to position a hot wired anemometer in the test section?

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#40
In reply to #39

Re: Wind Tunnel Project

10/03/2016 7:25 AM

If it was me, I would place it as close to the test area as where your test element of what you are testing as close as possible without interfering with the flow data.

Nothing is perfect.

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#41
In reply to #38

Re: Wind Tunnel Project

10/03/2016 9:21 AM

You want to place the hot wire perpendicular to the flow, in a location which will disturb the flow as little as possible (as mentioned several times above). You also want to consider boundary layer effects, so keep your anemometer away from walls etc.

"How to measure the temperature difference of the test piece".... not sure what you are asking here. To set up the hot wire anemometer in the first place you will need a known flow velocity to subject the heated wire to. Then you calibrate your equipment based on that known value. The current in the wire is proportional to the speed of the flow over the wire. As the flow cools off the wire, the current in the wire (and therefore the voltage that the logging equipment is subjected to) adjusts accordingly.

You have an interesting apparatus, and good potential for some interesting results - good luck!

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