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fluen reference values for blade area and length |
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#1 |
New Member
MUHAMMAD NOUMAN NAZIR
Join Date: Sep 2018
Posts: 5
Rep Power: 7 ![]() |
hello everyone
i need some clarification about reference value in fluent like area and length of wind turbine blade in my geometry there is no hub and blade is offset from origin by hub radius. if i consider hub radius as r and blade length after hub as R then total radius from origin becomes r+R now if i just consider blade swept area excluding hub for 120 deg domain i used pie*(R^2)/3 i got higher torque co efficient as compare to if consider following area pie*(R^2-r^2)/3 so i am really confused which method is standard one. there is no hub so there is no force or torque on that region what should i consider blade area and length BLADE AREA ,,, LENGTH PIE*((R+r)^2 )/3 = (1.55m^2) , r+R=(1.21m),,,r=0.19m PIE*((R)^2)/3 = (1.24m^2) , R=(1.09m) PIE*(R^2-r^2) /3 = (1.533m^2)) , R=( 1.09m) kindly guide me on this issue Thanks Best regards M Nouman Nazir |
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#2 |
Senior Member
Lucky
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 5,728
Rep Power: 66 ![]() ![]() ![]() |
There is not one single torque coefficient. The reference area and length is decided when you define what is the torque coefficient. I.e. you want to compare your coefficient with somebody else's, then you ask them what reference area and length they used in their torque coefficient. Otherwise, you calculate a different coefficient.
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#3 |
New Member
MUHAMMAD NOUMAN NAZIR
Join Date: Sep 2018
Posts: 5
Rep Power: 7 ![]() |
actually i have two design of blade one is baseline and other is improved one.....so i have to compare them ....in any case whatever i put reference area and length for both blades i got higher cm for improved case......but i wanted to make sure that what is standard method.......can you help me out picking the right formulas for reference blade area and length
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#4 |
Senior Member
Lucky
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 5,728
Rep Power: 66 ![]() ![]() ![]() |
If you haven't decided on an area and length then there is no meaning to calculating any coefficient. Just compare actual torque values if that's the case.
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#5 |
New Member
MUHAMMAD NOUMAN NAZIR
Join Date: Sep 2018
Posts: 5
Rep Power: 7 ![]() |
so reference values not affect actual torque for both cases?
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#6 |
Senior Member
Lucky
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 5,728
Rep Power: 66 ![]() ![]() ![]() |
Reference values are for calculating derived values like coefficients only they don't affect any solution values. You can check this easily. Just put in non-sensical numbers for them and watch how the solution doesn't change.
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#7 |
New Member
MUHAMMAD NOUMAN NAZIR
Join Date: Sep 2018
Posts: 5
Rep Power: 7 ![]() |
ok.....i will try it.....
Thanks |
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#8 |
Senior Member
Lucky
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 5,728
Rep Power: 66 ![]() ![]() ![]() |
Just do it. It's only a few button clicks. There's nothing to be scared about. Explore! Learn something about Fluent. Good Luck.
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