Experimental and numerical approaches for the quantification of tumble intensity in high-performance SI engines

The results showed that the HWA technique represents a factual alternative to the integral techniques for tumble characterization. It also provides additional information about the unevenness of the flow distribution generated by the intake system. The 'virtual flow box' simulations pointed out that good results can be obtained by using the Realizable k-ε model, whereas both the Realizable and the RNG k-ε models proved to be appropriate for the engine transient simulations. Finally, the CFD models showed to be fairly accurate and reliable, especially when the relative changes from one engine geometry and/or valve actuation to another need to be accounted for.