# Intake manifold analysis

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 June 30, 2008, 08:21 Intake manifold analysis #1 mehndan Guest   Posts: n/a 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.

 June 30, 2008, 08:39 Re: Intake manifold analysis #2 JT Guest   Posts: n/a 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.

 June 30, 2008, 10:58 Re: Intake manifold analysis #3 Steve Guest   Posts: n/a Uh? Intake manifolds are like musical instruments. Absolutely dominated by pressure waves. I really doubt you are doing a steady flow calc.

 June 30, 2008, 11:16 Re: Intake manifold analysis #4 JT Guest   Posts: n/a Mehndan, Is this for an engine intake or musical instrument? Can you provide some more background to the problem please? JT

 July 1, 2008, 04:26 Re: Intake manifold analysis #5 mehndan Guest   Posts: n/a 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?

 July 1, 2008, 05:33 Re: Intake manifold analysis #6 JT Guest   Posts: n/a 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

 July 3, 2008, 05:28 Re: Intake manifold analysis #7 Steve Guest   Posts: n/a Ahh (sound of penny dropping). I assumed you were studying the intake manifold of a piston engine.