Evaluation and analysis of injection strategy in a peripheral ported rotary engine fueled with natural gas/hydrogen blends under the action of apex seal leakage

Natural gas/hydrogen blended fuel (NHBF) is considered as one of the most promising alternative fuel for rotary engine. The aim of this paper is therefore to analyse the influence of injection angle (IA) and injection timing (IT) of blended fuel on the combustion performance of a peripheral ported rotary engine fueled with NHBF. Meanwhile, considering that the apex seal leakage is an unavoidable phenomenon during the operation of a rotary engine, the action of the apex seal leakage on flow field and combustion process cannot be ignored. Therefore, a 3D calculation model of the peripheral ported matry engine, considering the apex seal leakage, was firstly established in this study. Furthermore, under the action of the apex seal leakage, the diffusion and combustion processes of NHBF in the cylinder with different ITs and IAs were calculated. The results indicated that for the distribution of NHBF, when the IT is in the intake stoke, the IA has no obvious effect on the distribution of NHBF. However, when the IT is in the compression stoke, with the increase of IA, the mass of the blended fuel distributed in the back of the cylinder decreases, and the blended fuel continuously accumulates at the middle and front of the cylinder. For combustion process, when the blend fuel injection strategy is Case: 150 + 0, whose installation angle of the blend fuel nozzle is perpendicular to the cylinder block with a IT of 150 degrees CA (BTDC), the blended fuel at spark timing is mainly distributed in the middle and front of the cylinder, which is conducive to the improvement of combustion speed in the cylinder. As a result, compared with other calculation cases, Case: 150 + 0 has the highest combustion speed in the cylinder. Therefore, the IT and IA of Case: 150 + 0 are recommended in the practical engineering application to improve the combustion performace of the peripheral ported rotary engine fueled with NHBF.