Influence of Inlet Flows on the Flow Field in an Engine

Air velocities at several points near the spark plug location were measured using a laser Doppler anemometer (LDA) in a motoring internal combustion engine. This engine was equipped with three intake configurations: a standard valve in a standard port, a standard valve in a helical (swirl) port, and a shrouded valve in a standard port. Both ensemble-averaged and cycle-resolved mean velocities were determined; this allows comparison of rms velocity fluctuation, cycle-resolved turbulence, and cycle-by-cycle variations in mean velocity. Frequency domain analysis of these components was also carried out. The main conclusion of this experimental study was that starting from a very low swirl situation (standard valve case), addition of a moderate amount of swirl (swirl port case) goes a long way towards improving cycle repeatability and increasing cycle-resolved turbulence. Increasing swirl even further (shrouded valve case) does not produce further dramatic improvements.