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 PLenchette Julien March 5, 1999 18:12

inlet valve meshing and calculation

My research project is about a cylinder head design and intake flow calculation. We already Designed the cylinder head with Catia but we are now investigating about the kind of meshing and method we must use and the errors we must expect on this kind of computing. We must use Fluent and probably GEOMESH. Do you have any experience of this kind of calculation? Do you know the errors between CFD and Experiment we should expect? thanks for your advices and answers.

PS:the piston is considered fixed for a position of the valve. Can you give me advices for the boundary conditions? and this is very important, Do YOU HAVE AN IDEA OF THE ERRORS OBTAINED IN COMPARISON WITH EXPERIMENT IN ALREADY MADE CALCULATIONS?

Thanks Julien Plenchette

 Clifford Arnold March 5, 1999 18:37

Re: inlet valve meshing and calculation

To be specific: In two cases published by the JSAE (referred to as Engine 1 and Engine 2) Fluent overestimated the CD by 4% and 8% for two different grids for Engine1 and by 24% and 6% for Engine2. Other codes had similar errors.

Local values for velocity at two locations were also reported: Fluent underestimated the velocity in the jet produced by the valve seat by 5% to 10% and in an area of separation near the valve skirt the velocity was overestimated by a factor of 2.5. These values were similar for most other codes though some did better in estimating the velocity in the separated area.

It is my opinion (as stated before) that the errors generated are rather dependent on the details of the grid. Therefore results will vary with the user's choice of grid more than the choice of CFD code.

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