Windtunnel Airspeed Indicator

[Tom Núñez]

Hi All.

I am currently constructing a wind tunnel with some friends and we'd like a means of measuring airspeed within the wind tunnel.

Ideas include:
- Pitot tube with differential pressure sensors
- Load cell to measure force and convert to airspeed

The sensor/cell will be hooked up to an arduino uno and programmed to display airspeed on a pc or lcd. Price isn't really an issue but I thought something like this would suffice:

The sensor must be able to handle wind-speeds of up to 45m/s.

Advice would be greatly appreciated - this project is to be displayed at an engineering show in 5 weeks!!

Many thanks

Tom

 

[Gryd3]

Hi All.

I am currently constructing a wind tunnel with some friends and we'd like a means of measuring airspeed within the wind tunnel.

Ideas include:
- Pitot tube with differential pressure sensors
- Load cell to measure force and convert to airspeed

The sensor/cell will be hooked up to an arduino uno and programmed to display airspeed on a pc or lcd. Price isn't really an issue but I thought something like this would suffice:

The sensor must be able to handle wind-speeds of up to 45m/s.

Advice would be greatly appreciated - this project is to be displayed at an engineering show in 5 weeks!!

Many thanks

Tom

Use anything you want temporarily to calibrate the fan. You can develop a look-up table to convert to-from RPM to AirSpeed. Of course, air-speed is not going to be 100% constant, and obstructions within the tunnel will alter the wind-speed. Keep in mind that the 'pilot' tube method is used on the model itself in the tunnel to determine wind speed across a given surface.
Additionally, you mention an upper limit to the speed it must handle, but no accuracy or resolution.

 

[KMoffett]

"the 'pilot' tube" ??? "Pitot" tube is the correct term.

Ken

 

[(*steve*)]

How about a hot wire?

 

[Gryd3]

How about a hot wire?

I didn't even consider that!
Often used in automative. Great Idea.

Edit : Link > https://en.wikipedia.org/wiki/Mass_flow_sensor

 

[hevans1944]

If price is no object, then a Laser Doppler Anemometer (LDA) is the way to go. Can be calibrated using a method developed by NIST. See this PDF for calibration details. Some assembly required for calibration.

 

[duke37]

I used to use a hot wire detector on a vehicle. It became known as the bee catcher.

 

[Tom Núñez]

Thank you all for the replies.

Gryd3: I am aware of disruptions to the airflow etc. and the accuracy isn't crucial however more of less with 2-3m/s error would be adequate.

The plan is to measure a known airspeed with an anemometer and measure these on the fan dial. The voltages then obtained through the arduino (from the pressure sensor) can be converted into corresponding speeds.

Also, is it always essential to use a shield when using sensors with arduino? I only need 2 inputs for the sensor and I think 6 are needed to use the LCD.

 

[Colin Mitchell]

You can also get a chip with hole in it to measure air pressure. This is the best as there are no moving parts and it costs $2.00

 

[KMoffett]

You can also get a chip with hole in it to measure air pressure. This is the best as there are no moving parts and it costs $2.00

Got a link?

Ken

 

[Colin Mitchell]

1PCE BMP180 Replace BMP085 Digital Barometric Pressure Sensor


http://www.ebay.com/itm/1PCE-BMP180...2d8e9d0&pid=100005&rk=1&rkt=6&sd=221485468940


US $2.97

It was US $1.90 last week.

 

[KMoffett]

Wow! Unfortunately, a static-pitot air speed indicator needs a differential pressure rather than an absolute pressure sensor like that one. And a very sensitive sensor, with a full scale range of about 100 mmH2O or 3 inH2O or 0.15 PSI for 45m/s.
http://www.engineeringtoolbox.com/pitot-tubes-d_612.html

Ken

 

[poor mystic]

Thank you all for the replies.

Gryd3: I am aware of disruptions to the airflow etc. and the accuracy isn't crucial however more of less with 2-3m/s error would be adequate.

The plan is to measure a known airspeed with an anemometer and measure these on the fan dial. The voltages then obtained through the arduino (from the pressure sensor) can be converted into corresponding speeds.

Also, is it always essential to use a shield when using sensors with arduino? I only need 2 inputs for the sensor and I think 6 are needed to use the LCD.

I think that shielding is always important when making measurements with electronics. In fact I think it should be separately earthed so that stray currents from the Arduino can't easily feed into the signal you're trying to measure.

 

[Gryd3]

I think that shielding is always important when making measurements with electronics. In fact I think it should be separately earthed so that stray currents from the Arduino can't easily feed into the signal you're trying to measure.

I think the 'shield' in question was not actually an earth or EM shielding.
Add-on boards for many of the Electronic projects are being called 'shields' or 'capes'.
To answer the OPs question... no, you don't need an add-on board, unless the Arduino you have in particular is not able to connect to the sensor, or you can't be bothered with connecting your own external components to make a sensor work,
Mystic has a great point in that using sensitive sensors may pick up stray interference from electrically noisy sources. There are numerous methods to protect against this, and one of which is 'shielding'