The Use of Coherence Techniques to Predict the Effect of Engine Operating Parameters on Diesel Engine Noise

A technique is presented in which the effects on noise of changing diesel engine operating parameters can be predicted. Traditionally, the effects have been determined by experiment. The technique presented in this paper utilizes experimentally determined frequency response functions between each cylinder pressure input and the engine noise. Once the frequency response are measured, the engine noise can be calculated for an arbitrary cylinder pressure input. The effect of injection timing, engine load, and engine speed are predicted using cylinder pressure histories obtained from a single cylinder research engine.