Combustion and gas-side thermal exposure of the rotor wall in a hydrogen-fueled oval rotary engine: effects of intake air temperature and excess air ratio

The oval rotary engine (ORE) is a novel rotary engine with broad application prospects in power systems such as unmanned aerial vehicles. When fueled by hydrogen, it provides a promising pathway for deep decarbonization in the power field. However, high and spatially non-uniform rotor thermal environment and low efficiency limit its further applications. This study investigates the effects of intake air temperature (IAT) and excess air ratio (λ) on combustion, gas-side thermal exposure, and performance. At λ = 2.2 and IAT = 240 K, the peak near-wall gas temperature and near-wall gas-temperature difference decrease by 27.1% and 67.38%, respectively, relative to the baseline (λ = 1.8, IAT = 300 K), while ITE decreases to 19.7%. Among the investigated cases, IAT = 300 K and λ = 2.2 yields the highest ITE (37.6%) while maintaining an IMEP of 0.499 MPa and relatively low gas-side thermal exposure, representing a representative compromise condition.