利用倒拖法对某车用涡轮增压缸内直喷汽油机空载加速和半载加速工况进行了燃烧噪声试验研究。联合发动机缸内燃气压力测试结果，通过分析气体动力载荷对其燃烧噪声的影响，进一步探讨燃烧噪声产生的根本原因。试验结果表明，在中低转速时，燃烧噪声随着发动机负荷的增加而增加，同时燃烧噪声对整机总声功率的贡献值也在随之增加。在较高转速时，燃烧噪声对整机总声功率的贡献值随着发动机负荷的增加变化不显著。就半载加速和空载加速工况时燃烧噪声的平均贡献值来看，空载加速时燃烧噪声对整机噪声的平均贡献值为22.2%，明显小于半载加速时的43.6%。随着发动机转速的提高，最大气缸压力及最大压力升高率总体变化趋势和燃烧噪声变化趋势一致，同时加速时最大气缸压力变化对燃烧噪声的影响更明显。

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.