Friday, 26 November 2010

CFD Model Calibration

In order to have any confidence in the CFD analysis I will be undertaking, I need to check that the model has some bearing on reality. I have the flow bench data for the cylinder head I am intending to use so I want to know how well my CAD model matches up with the empirical information. To achieve this, I have created a 3D model of the cylinder head and set it up in a virtual flow bench i.e. I added a radiused inlet port and a pipe to represent the cylinder.

Then it was a simple task of adding the pressure drop according to the real flow numbers I have and running the simulation for a number of different valve lift values. The results are as follows:

As you can see, the predicted flow numbers correlate reasonably well with the measured values. There is around 7% difference in the region of interest, which considering the CAD model has been cobbled together from photos and limited dimensional data available on the web, I think is none too shabby. I will only be using the model to compare different options rather than looking at absolute values, so I believe this is a reasonable starting point.

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