消音スパイクによる燃焼騒音加振力の低減

抄録

The author's previous study addressed combustion noise reduction by optimizing the interval between two peaks in the pressure rise rate (dP/dθ) of PCCI combustion with the split injection of fuel in diesel engines. Noise canceling occurs between two dP/dθ peaks, which reduces the overall combustion noise by lowering the maximum frequency component of the noise spectrum. The period of this frequency is twice the interval between the two dP/dθ peaks. We named this noise reduction technique ‘noise-canceling spike' because it relies on interference between a spike in the pressure rise and the preceding peak in the pressure rise. On the other hand, the amplitude of the frequency component, the time period of which corresponds to the interval between the two dP/dθ peaks, increases as a result of the overlapping of these peaks. The noise-canceling spike is a universal phenomenon which occurs between the two dP/dθ peaks independently of the combustion (injection) strategy. If there are three or more dP/dθ peaks, the noise-canceling spike can occur between every pair of dP/dθ peaks.