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Old   October 6, 2007, 02:34
Default Help with Boundary Conditions
  #1
chun wee
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Hi,

I have problem in assigning BC for propeller simulation. I use fan BC to represent the propeller. I draw a tube isolating the fan surface. The BC is pressure inlet --> fan --> pressure outlet and the skin of the tube is symmetry.

Am I using the right BC?

I have Thrust vs RPM data from experiment. I can calculate the induced velocity and pressure jump using momentum theory.

I set the P operating as 1 atm. I notice that the P total in inlet should be around 1 atm and at inlet the P static is 1 atm, whereas the P total is unknown.

What should I put in gauge pressure column at Pressure inlet and outlet BC?

Right now, I keep it 0. It gives me wrong physical characteristics. the velocity is almost uniform everywhere, while the Velocity at oulet (V advance is 0 for hover condition) should be 2x the velocity at the fan surface.

I think I have made a mistake....
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Old   October 6, 2007, 08:09
Default Re: Help with Boundary Conditions
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jesse
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1.formula to calculate P total in respective to mach number 2.operating number at inlet set to 0 when not big pressure drop 3.specify the BC at Propell in cell zone Fluid?(i am also not sure about that,cos so far i dealt not too much with propell)
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Old   October 6, 2007, 09:01
Default Help with Boundary Conditions
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chun wee
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Hi jesse,

Thank for your answer. Isn't that total pressure as M function is for compressible flow? I'm simulating incompressible flow since the velocity is very low. Have you tried similar model before? maybe you can share your experience.

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