Experimental Study on Combustion Noise in Transient Conditions of DI-Diesel Engine

This paper studies the effect of transient conditions on combustion noise of DI-Diesel engines. After testing technique and method of transient conditions have been developed, the law that governs the difference of combustion noise in transient conditions and that in steady conditions in the same load and at the same rotation speed can be found. By studying the difference of the combustion process in transient conditions and steady conditions, the paper analyzes the results of testing. It will result in differences of the ignition delay, start point of combustion, and fuel injection quantity in transient conditions and those in steady conditions since the combustion chamber wall's temperature, fuel injection pressure, maximum needle lift and unseal standing time of needle lift in transient conditions are higher than those in steady conditions in the same load and at the same rotation speed. The result shows that the difference between the aerodynamic load as well as high-frequency oscillation of combustion pressure in transient conditions and those in steady conditions in the same load and at the same rotation speed result in different combustion noise.