DI DIESEL ENGINE BECOMES NOISIER AT ACCELERATION - THE TRANSIENT NOISE CHARACTERISTIC OF DIESEL ENGINE - 790269
An acceleration mode in measuring vehicle pass-by noise was simulated on an engine test bed in an anechoic room. The accelerated running noise of various types of diesel engines was measured and compared with the steady running noise. The measurement results show that naturally aspirated DI engines become noisier at acceleration, while IDI engines change only slightly. In turbocharged DI engines, the response lag of the turbo charger causes an especially big noise level difference immediately after acceleration start. This paper deals also with the mechanisms of higher level of accelerated running noise in DI engines.