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mehndan June 30, 2008 08:21

Intake manifold analysis
I am going to simulate an engine intake manifold by star ccm+ .I have msss flow at inlet and pressure at outlet. Please answer to these questions:

1- These analysis should be compressible or incompressible?

I ran incompressible analysis , and as expected I found little pressure change. But I suspect that, this may be compressible analysis. Kindly guid me for this.

JT June 30, 2008 08:39

Re: Intake manifold analysis
Compressible vs. Incompressible flow depends on the speed of the flow entering the intake. For Mach numbers less than 0.3-0.5(ish), I'd say you are in the incompressible range.

Steve June 30, 2008 10:58

Re: Intake manifold analysis

Intake manifolds are like musical instruments. Absolutely dominated by pressure waves. I really doubt you are doing a steady flow calc.

JT June 30, 2008 11:16

Re: Intake manifold analysis

Is this for an engine intake or musical instrument? Can you provide some more background to the problem please?


mehndan July 1, 2008 04:26

Re: Intake manifold analysis
Hi Thanks for response. Its for engine intake. I got around 150 m/sec velocity when running incompressible analysis, thats why I doubted that, it may be compressible flow. what are your suggestion?

JT July 1, 2008 05:33

Re: Intake manifold analysis
guessing this is for an aircraft - which then raises the question of what pressure altitude are you simulating this model at, because the local speed of sound differs at various altitudes. Something that is compressible at a certain altitude, may or may not be compressible at another.

Drop me an email directly if you need further suggestions

Steve July 3, 2008 05:28

Re: Intake manifold analysis
Ahh (sound of penny dropping). I assumed you were studying the intake manifold of a piston engine.

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