CFD Study of Spray Design for a GDI High Performance 2-Stroke Engine

The advantages of 2-stroke engines, high power and low weight, are in conflict with their disadvantages, high emissions and bad fuel economy. As these disadvantages are caused by the scavenging process, a reason for the problem can be analyzed by using three dimensional computational fluid dynamics simulation (3D CFD simulation). The scavenging losses can be dramatically reduced with a high pressure fuel injection strategy. The purpose of this strategy is to prevent a fuel concentration in the incoming charge and to reduce the fuel concentration inside the exhaust system. These advantages can only be successfully exploited with the application of an optimal injection strategy.

This paper covers a spray study for a gasoline direct injection (GDI) high performance 2-stroke engine using the commercial CFD Code Fluent. The simulations were conducted for four different engine operating points and the test bench results of the fired engine were used for the validation of the gas dynamic behavior simulation inside the engine. The main focus of the present paper lies on the simulation methodology used for the fuel injection simulation. The used injection settings and their validation results are presented and discussed in detail. The assessment and definition of the best injection strategy for a 2-stroke engine at high engine speed is a demanding task and presented in this paper.