Expert: Heiko Hanusch - 4/19/2006

Question
I wasn't sure if you could answer this for me, but I've tried looking everywhere for this information.  I am currently working on a piezoelectric windmill and I am testing our blades for the drag coefficient as the wind velocity is varied from 0 to 20 mph.  In order to determine the drag coefficient for our blade, I tested a halfpipe and v wedge shapes at the same wind speeds.  I need to compare the drag force of these shapes to my blade in order to determine the drag coefficient.  The problem is, I have only been able to find a constant drag coefficient for high velocities for the cup and v shape I have tested, but no data where the drag coefficient varies at the wind speed increases.  Is there any place where I could find this information or are you aware of any drag coefficients for these shapes?  Thank you for your help!  

Answer
Hi Vadim,

Thank you for your question.
I am not sure if I can help you here, this goes beyond my expertise. There are several Software programs that might help you though.
I found this website (.pdf file) from Sweden and they determined the variable drag coefficient using a program called "POWERSIM". Go and read their file and hopefully it will help you.

http://www.bme.hu/ptee2000/papers/osterl.pdf

Sorry I could not be of more help,

H2