Experimental and Computational Methods for Swirl Port Design in Internal Combustion Engines

The paper reviews the minimum losses and intake flow conditioning criteria typically adopted for the design of swirl ports in two valve Direct Injection (DI) Diesel engines, as well as in some two valve Spark Ignition (SI) engines. The standard experimental practice, based on the use of steady flow discharge and swirl coefficients as a measure of port design quality is first presented. The analogous computational methodology, where the steady flow is simulated, is then introduced. The computational methodology is extensively validated against a data set for a series of ports, of the direct, hybrid and helical type. The computational methodology is finally applied to simulate the transient flow within the engine during the intake stroke. The computed Intake Valve Closure (IVC) flow field provides a more rational basis for port optimization than steady flow coefficients, even if these latter simulations have still to be properly validated.