A Study on the Spray Characteristics of SIDI CNG Engine Based on a Visualization System

Abstract

Compressed natural gas (CNG) is regarded as one of the most promising alternative fuels, is widely used for the automobile engines. In order to improve the thermal efficiency of CNG engine, the direct-injection (DI) technology has been adopted. The stratified CNG mixture can be ignited by the spark plug which is installed near the injector nozzle, so the lean combustion can be subsequently achieved. For the direct-injection spark-ignition (DISI) engine, the reliable ignition is a foundational problem for the reliable operation, so it is very important to study on the spray characteristics of DISI engine. In our study, a combustion chamber is designed and a visualization system is built. The DI CNG spray's injection process was digital recorded with the schlieren optical system under different experiment conditions. The spray characteristics of the DI CNG engine were analyzed with the experimental results.