进气道滚流比对发动机压升率及噪声的影响

Effect of intake port tumble ratio on engine pressure rise rate and noise

以某双喷射6缸发动机为研究对象,设计高滚流比和低滚流比2种进气道,通过三维计算流体动力学软件AVL Fire对缸内流场进行仿真,分析发动机燃烧特性,并进行台架燃烧测试和噪声测试。仿真结果表明:在转速为2800 r/min、平均有效压力为1.3 MPa工况下,相比高滚流进气道方案,低滚流气道方案的缸内第一、二个峰值滚流比分别降低了43.3%、34.9%,最大缸内平均压力降低544 kPa,最大压力升高率降低16.84%。台架试验结果表明:2种进气道的燃烧持续期相差不大,相比高滚流进气道方案,低滚流方案以曲轴转角表示的燃烧重心推迟了2.02°,燃油消耗率增大0.67%,压力升高率(压升率)降低了19.87%,发动机在频率为700~1300 Hz时的噪声约降低6.0 dB,噪声改善效果明显。

Taking a certain dual injection 6-cylinder engine as the research object,two types of intake ducts with higher and lower tumble ratio are designed.The cylinder flow field is simulated using the three-dimensional computational fluid dynamics software AVL Fire,the combustion characteristics of the engine is analyzed,and bench combustion tests and noise tests are conducted.The simulation results show that under the condition of a speed of 2800 r/min and an average effective pressure of 1.3 MPa,compared with the higher tumble ratio scheme,the first and second peak tumble ratios in the cylinder of the lower tumble flow scheme are reduced by 44.3%and 34.9%,the maximum average cylinder pressure is reduced by 544 kPa,and the maximum pressure rise rate is reduced by 16.84%.The bench test results show that the combustion duration of the two intake ducts is not significantly different.Compared with the higher tumble ratio scheme,the tumble ratio scheme has a combustion center of gravity delayed by 2.02°in terms of crankshaft angle,an increase in fuel consumption rate of 0.67%,a decrease in pressure rise rate of 19.87%,and a reduction of about 6.0 dB in engine noise at frequencies of 700-1300 Hz.The noise improvement effect is significant.