The formation mechanisms of flow field in a compound intake ported rotary engine considering apex seal leakage

Abstract

The development of rotary engines is severely restricted by its low combustion efficiency and high emission. In-cylinder flow field is known to play a major role in combustion process for rotary engines. Therefore, in the present article, a threedimensional dynamic simulation model considering leakage through apex seals was developed and verified by the two-dimensional particle image velocimetry experiment results on the rotor housing central plane. Based on the three-dimensional dynamic simulation model, the formation mechanisms of flow field in a compound intake ported rotary engine under different apex seal leakage gap sizes (0.02, 0.04, 0.06, and 0.08 mms) and engine speeds (2,000, 3,500, and 5,000 rpms) were numerically studied. The simulation results showed that there exist two formation mechanisms of the flow field in the intake stroke, that is, "side intake port dominance" and "peripheral intake port dominance." For the three engine speeds (2,000, 3,500, and 5,000 rpms), with the increase of apex seal leakage gap size, the formation mechanism of the flow field gradually changed from "side intake port dominance" to "peripheral intake port dominance." In addition, the influences of apex seal leakage on the volume coefficient and the turbulence kinetic energy in the combustion chamber were also investigated in detail. K E Y W O R D S apex seal leakage, compound intake port, flow field, rotary engine 1 | INTRODUCTION With the increasingly serious energy crisis and environmental problems, it is urgent to develop new types of engines that have higher efficiency and lower pollution. 1,2 As a new type of engine, with simple structure and high power-to-weight ratio, rotary engines have been widely used in many fields, such as aircraft, cars and motorcycles for many years. 3 In particular, the rapid development of small unmanned aerial vehicles (SUAVs) and range extended electric vehicles (REEVs) in recent years has provided new opportunities for rotary engines. This is mainly because SUAVs and REEVs need a small size and high power-to-weight power device, and rotary engines can well meet the above requirements. 4 For example, a range extender with a rotary engine designed by AVL List GmbH is regarded as one of the most promising power generation mode for REEVs. 5 Because of the above promising application prospects, the investigation, and development of rotary engines have attracted more and more attention from many countries and research institutions. 6