A Conjugate Heat Transfer Analysis of a Rotary Combustion Engine with a Focus on the Effect of Thermal Barrier Coatings 2023-01-0199

In recent years, rotary combustion engines have experienced renewed interest as alternative power sources in various applications, due to their multi-fuel capability, simplicity, and advantageous power-to-weight, and power-to-volume ratios. Further improvements to the engine's performance require a thorough examination of its inherent shortcomings. Most prominent are its incomplete, slow combustion and lower thermal efficiency, both of which are caused by the combustion chamber's high surface-to-volume ratio and unfavorable flattened shape. Considering the difficulties involved in performing experimental measurements on rotary combustion engines, numerical simulations have proven to be valuable tools for research and development. This study presents a validated three-dimensional RANS model that simulates the flow, reaction kinetics, and heat transfer in rotary combustion engines. The model incorporates a conjugate heat transfer approach, which couples the heat transfer between the solid rotor, the convective airflow within its core, and the gas in the combustion chamber. Different heat transfer models and meshing approaches were evaluated as part of the development of the model for high load/high revving speed applications. Lastly, an advanced thermal barrier coating was proposed for use in rotary combustion engines. The developed model was modified to include a temperature discontinuity at the solid-gas interfaces of the rotor, which is related to the thermal resistivity of the coating. It was predicted that the application of the coating would reduce heat losses by 10 %, lower the mean temperature of the rotor by 4.6 %, and improve the fuel conversion efficiency by 1.3 %. The results suggest that an advanced thermal barrier coating can reduce thermal loads and enhance the performance of rotary combustion engines.