Numerical simulation analysis on the effect of structural parameters on the comprehensive performance of an aviation heavy-fuel rotary engine

Aviation heavy-fuel rotary engines are widely used in the field of small unmanned aerial vehicles. In this study, 1-D and 3-D simulation models of an aviation heavy-fuel port fuel injection rotary engine based on experimental validation were constructed. Based on these models, numerical analyses were conducted to investigate the effects of injector position L1, injection angle θ, and trailing spark plug position L2 on mixture formation, combustion, and emissions in the engine. Results show that increasing L1 enhances fuel capture rate θc and peak in-cylinder pressure Pmax, with optimal performance at L1 = 29.6 mm. When θ is reduced to 25.8°, mixture distribution and combustion rate are improved. L2 primarily affects the combustion of the mixture in the rear part of the combustion chamber. NOX emissions first increase then decrease with increasing L1, decrease with decreasing θ, and increase with increasing L2. Soot emissions correlate positively with L1 while negatively with θ, and L2 has minimal effect. Using the entropy weight TOPSIS method, the optimal parameters are determined as L1 = 19.6 mm, θ = 25.8°, L2 = 13.2 mm, achieving a 9.59 % increase in θc, 5.57 % higher Pmax, and 31.29 % lower NOX emission quantity compared to the original scheme. These findings provide a theoretical basis for optimizing heavy-fuel rotary engine design.