Combined Effect of Air Intake Method and Hydrogen Injection Timing on Airflow Movement and Mixture Formation in a hydrogen direct injection rotary engine

Abstract

The hydrogen rotary engine (HRE) has advantages of the high power-to-weight ratio and low emission performance. In this study, a three-dimensional dynamic simulation model of the hydrogen direct injection rotary engine is established, and the accuracy and reliability of the gas nozzle injection model are verified based on experimental data in detail. Then, the combined effects of the air intake method (AIM) and hydrogen injection timing (HIT) on airflow movement and mixture formation processes in the HRE are investigated. The numerical results show that the compound AIM improves the engine volumetric efficiency due to more air entering. As for air movement, the average airflow velocity and turbulent kinetic energy both increase significantly during hydrogen injection duration under different HITs and AIMs. In terms of mixture formation, using compound AIM, more hydrogen accumulates near the ignition chamber compared to the peripheral and side AIMs. Also, when HITs are −286°CA and −190°CA, hydrogen concentrates near the ignition chamber, which will be conducive to the subsequent combustion process due to the RE's flame forward propagation characteristics. Comprehensively considering the airflow movement characteristics and fuel distribution rule, the peripheral AIM and the compound AIM, which their HITs are set at the compression stage (−190°CA), namely Case7 and Case9, are preferred schemes. This paper can provide some theoretical guidance for the intake structure design, injection strategy optimization and mixture rational organization of the HRE. • Airflow movement and mixture formation of a hydrogen rotary engine is explored. • The gas nozzle injection model is detailly validated based on experimental data. • Effect of air intake method and fuel injection timing on the flow process is studied. • Ideal schemes (Case7 and Case9) are obtainedby analyzing fuel distribution rules.