Calculations and measurements in the cylinder of a two-stroke uniflow-scavenged engine under steady flow conditions

An experimental study of the flow pattern inside a model cylinder of a uniflow-scavenged two-stroke engine is presented. The velocity field as well as the turbulent parameters were mapped under steady-flow conditions with the aid of a hot-wire anemometry technique. A detailed computer program was used to predict the gas exchange process. The program DICE-2, based on axisymmetric calculations in a cylinder with valve-controlled ports, was modified to facilitate calculations in a piston-controlled ports arrangement that is typical in two-stroke engines. Predictions are compared with experimental observations, and it is concluded that even if a relatively simple cylinder model is chosen and operated under steady flow, it is still difficult to get very good agreement between calculations and measurements. The divergence of the measured and calculated results demonstrates the shortcomings of the k-ε{lunate} model.