Determination of Suitable MRF-Region for Practical Prediction of Engine Cooling Fan Performance

Recently, CFD technology has become popular to the prediction of the engine cooling performance for the design of the automotive engine cooling systems. Particularly, the practical prediction of the cooling fan performance is one of the important issues. In the design phase of the vehicle development, combinations of multiple parameters are generally examined. Certainly, the unsteady calculations such as LES or LBM, which require high resolution of the space, give good accuracy meanwhile they spend much time for their executions so that they are not always practical. Therefore, the steady RANS coupling with MRF method is indispensable. However, it has been pointed out that, in case of complicated layout around the fan of an actual vehicle, the size of the MRF-region dominates predictive accuracy while the symmetry of the flow structure is taken account. Then, in this study, attracting on the discontinuity at the boundary surface of the MRF-region, authors found the method to determine adequate MRF-region to predict the fan performance in practical accuracy. This paper deals with the outline of the method and their applications.