book collections email follower instructable user
Picture of DIY Wind Tunnel and Visualized Airstreams for the Physics Lesson
Windkanal_Video_15 0354.jpg


In my physics laboratory in one unit we treat the air resistance and the calculation of the cw value. This indicates how windy a body (such as a car) is. The formula for the aerodynamic resistance is:

Fr = 1/2 * cw * A * ro * v²


A .... the cross-sectional area of the object

cw ... the drag coefficient

ro ... the density of air

v ... the wind speed

As you can see from the formula, the air resistance increases with the square of the wind speed and linear with the cw value. Therefore, it is important for e.g. car designers to construct an aerodynamic body as possible. Today, the cw value of sports cars is between 0,2 and 0,3.

Step 1: The Parts You'll Need

Picture of The Parts You'll Need

The following parts are required for the laboratory unit:

* the wind tunnel made of acrylic glass

* the wind turbine with the three motors including propellers

* a dynamometer (dynamometer)

* a big car model

* Anemometer to determine the wind speed (anemometer)

* a strong, controllable 40A power supply (40A power supply)

* an e-cigarette (e-cigarette)

* a small pump (pump)

* E-cigarette liquid

* Rosin (rosin)

* Wire

For the construction of the wind tunnel:

The wind turbine consists of a 200mm PVC pipe. There are 3 powerful motors which need voltages between approx. 3V and 15V. These are powered by a single, powerful 40A power supply or 3 weaker separate power supplies. The motors are screwed by means of pipe clamps to a threaded rod. The diameter of the propellers should only be slightly smaller than the inside diameter of the PVC pipe. To protect the pupils against injury, a grid can be attached to the entrance of the PVC pipe.

The wind tunnel itself is made of acrylic glass. The individual parts are connected with special glue.

hi, i was just wondering if there was anything other than an e-cigarette i could use?
stoppi71 (author)  patrick andrew1 month ago
Hi! You could try it with dry ice or an ultrasonic-atomizer...
crisiacuf2 months ago
A very nice way of making a(more) laminar flow is to fill the section of the pipe(between the proppelers and DUT) with plastic straws.
stoppi71 (author)  crisiacuf2 months ago
Hi! Thank's for the tip. Right now I'm working on a smaller wind-tunnel especially to visualize the air flow:
There I use 5mm plastic straws ;-)
M-Parks4 months ago
I think with those propellers all spinning in the same direction and no flow straighteners you will get a non laminar flow, which is why the smoke stream was so turbulent. the air is spinning. I don't know why the second picture needs to be clicked on to be seen
download (1).jpgprop3.gif
stoppi71 (author)  M-Parks4 months ago
Hello! To get a more laminar flow I use a lot of drinking straws. In the video I didn't use them...
I have chosen the propellers to get a high wind speed for a measurable Force.
jessyratfink4 months ago
The flow lines came out so well! Loved looking at the photos :)
i agree...
benfero4 months ago
Well! I loved this photo..