Experimental research on engine combustion noise were
conducted on a turbocharged gasoline direct injection (GDI) engine through noload
and halfload motoring acceleration test. Combined with
measurement of incylinder burning gas pressure, the
effects of gas dynamic load on combustion noise were investigated to analyze
the root reason of combustion noise. The results show that engine combustion
noise increases with the increase of engine load at low and medium engine
speeds and the contribution of combustion noise to engine overall sound power
level also increases. But at high speed, the contribution is sensitive to
engine load increasing. In addition，the average
contribution of combustion noise to engine overall sound power is 22.2% and
43.6% respectively at noload and halfload acceleration conditions and the former is obviously lower than
the latter. Generally, the trends of maximum incylinder
gas pressure and maximum pressure rise rate agree with that of combustion noise
and the influence of maximum cylinder pressure on combustion noise is more
obvious.