Problems and Solutions for Sprays in Piston Engines

Abstract

Two of the most important criteria for assessing the performance of the modern diesel engine, namely economy and emissions, are strongly influenced by the atomisation of the fuel spray and its subsequent interactions with the ambient air during the early stages of injection. It is widely considered that any effective control of diesel engine combustion will be based on an improved predictive understanding of the momentum, concentration and temperature fields for both the liquid and gas phases. The experimental study of these parameters is difficult because of the complex interaction of several processes i.e. the sequence comprising atomisation, evaporation, mixing with the surrounding air, and auto-ignition. The problem is further complicated by high-speed transience, particularly in high-speed automotive engines, the droplet density and momentum, and frequently by the small physical scale of the engine.