Comparative study on ignition and combustion between conventional spark-ignition method and near-wall surface ignition method for small-scale Wankel rotary engine

Due to the existence of the ignition chamber, severe energy loss occurs in the combustion process of small-scale spark-ignition Wankel rotary engines (SI-WREs). Aiming at eliminating the adverse effects caused by the ignition chamber, the near-wall surface ignition (NWSI) method was proposed in this paper. This method eliminates the ignition chamber felicitously, thus shortening the flame propagation distance and reducing the complexity of combustible gas flow. Computational fluid dynamic (CFD) simulations of the conventional SI-WRE and the NWSI-WRE were carried out and analyzed together. The simulation results showed that, by applying the NWSI method, the peak pressure increased by as high as 25.23%. The NWSI method possessed characteristics of shorter ignition delay, faster combustion, and more rapid flame propagation than the conventional SI method. The superiority of the NWSI method is verified, providing a good reference for optimizing the ignition system of small-scale SI-WREs.