Materials to make skin friction negligible

In summary, the conversation discusses ways to achieve negligible skin friction while conducting wind tunnel tests on a foam model. The recommended approach is to make the surface smooth and even, possibly using a combination of liquids and sprays. The difficulty of measuring drag and the importance of reynolds number and skin friction in determining lift are also mentioned. A potential product that could help with achieving a smooth surface is suggested.
  • #1
eng1234
2
0
Hi,

I need to run wind tunnel tests on a simple shape which will be made of foam whilst the skin friction is to be negligible. Is there easy ways of cover the model to achieve this ?

thanks
 
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  • #2
The best you can do is to make the surface smooth and very even. Spray paint may not work because it often "eats" foam before it drys.
With some experimentation, you might find some combination of liquids and sprays that will work. Like a primer followed by a glossy coat. Or maybe a glue followed by a glossy. It will depend a lot on what foam you are using.
 
  • #3
Are you trying to measure the drag, or are you trying to measure lift? If you're trying to measure drag, it will be very difficult, and your best bet will be to try to get the reynolds number up as high as possible and make the surface as smooth as possible. If you're measuring lift however, it'll be a lot easier to ensure that skin friction isn't substantially affecting your results, though the procedure is the same (smooth surface, high Re). If you want to confirm that skin friction is small, run tests over a wide range of reynolds numbers and look at how your nondimensional coefficients are affected by changing Re. If your skin friction is having a negligible result on the aerodynamics, the nondimensional coefficients will not vary very much with Re.
 

1. What materials can be used to reduce skin friction?

There are several materials that can be used to reduce skin friction, including silicone, Teflon, and graphite. These materials have low coefficients of friction and can create a smooth surface that reduces friction between two surfaces.

2. How do these materials reduce skin friction?

These materials reduce skin friction by creating a barrier between two surfaces. This barrier reduces the amount of direct contact between the two surfaces, which in turn reduces the friction between them.

3. Are these materials safe for use on human skin?

Yes, these materials are safe for use on human skin. They are commonly used in medical applications, such as bandages and prosthetics, and have been deemed safe by regulatory agencies.

4. Can these materials be used in all environments?

No, these materials may not be suitable for all environments. For example, Teflon may not be effective in high-temperature environments, as it can melt and lose its low-friction properties.

5. How long do these materials typically last?

The lifespan of these materials can vary depending on the environment and the amount of friction they are exposed to. In general, they are durable and can last for several years before needing to be replaced.

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