气道稳流试验的变压差试验分析

用变压差试验方法测量了6108发动机缸盖进气道的流动特性。试验全过程不需要随时调节模拟气缸内的压差为恒定值。确定气门最大升程时模拟气缸内的初始压差后，就可采集试验中的流量和涡流转速等参数。随着气门升程变小，模拟缸内的压差自由增大。试验结果与恒压差试验相同，同样可以得到Ricardo和FEV计算方法的平均流量系数和涡流比。测量精度符合要求，操作程序简单可靠，易于实现气道稳流试验的全自动化。

An Analysis on Steady Flow Test with Variable in-Cylinder Pressure Drop

In this paper,a new steady flow test,i.e. steady flow test with variable in-cylinder pressure drop is proposed and performed. With this method,the in-cylinder pressure drop is no longer necessary to keep constant as Ricardo steady flow test does. In stead, the initial in-cylinder pressure drop is determined at maximum valve lift. Then with the valve lift lowers,the in-cylinder pressure drop rises and the parameters including flow rate and swirl velocity are measured naturally without any manual adjustment on in-cylinder pressure. The mean flow coefficient and swirl ratio are calculated using Ricardo and FEV methods as the conventional steady flow test do. Comparative test shows that the test results with variable in-cylinder pressure drop are basically the same as those with constant in-cylinder pressure drop. The new method has met the requirements of measuring accuracy but with much simpler operation and shorter measuring time,so is easier to realize the full automation of steady flow test and better suitable for on-line inspection of cylinder head on production line.