Experimental and Computational Fluid Dynamics Simulation Study on the Performance of a Two-stroke Aviation Engine: A Comparative Analysis of Turbulence Models and Mesh Strategies

This study presents an experimental and computational fluid dynamics (CFD) analysis to evaluate the performance of a two-stroke aviation engine under constant operating conditions. The experiments were conducted at 4800 RPM and full load, where high-precision measurement devices recorded critical performance parameters, including total mass flow rate, fuel mass flow rate, torque, volumetric efficiency, and in-cylinder pressure and temperature. For CFD analysis, a three-dimensional combustion chamber model of the engine was developed, and two turbulence models (Standard k-ε and RNG k-ε) were employed using three different mesh sizes (2 mm, 3 mm, and 4 mm). The numerical results were compared with experimental data to determine the most accurate simulation configuration. The findings indicate that decreasing the mesh size improves the accuracy of the simulations, with the Standard k-ε model using a 2 mm mesh producing the most precise predictions across multiple parameters. The error rate for total mass flow rate and volumetric efficiency was reduced to 9%, demonstrating the effectiveness of fine mesh resolution. However, the RNG k-ε model yielded better accuracy for specific fuel consumption, achieving a 0.1% error rate at a 2 mm mesh size. Velocity and temperature distributions revealed that flow gradients were more accurately captured with smaller mesh sizes, particularly in the bypass and exhaust port regions. The Standard k-ε model was more effective in predicting in-cylinder pressure and heat release characteristics, while the RNG k-ε model predicted slightly higher maximum in-cylinder temperatures. Mesh refinement significantly influenced combustion behavior, with smaller mesh sizes leading to more accurate heat transfer and reaction modeling. Overall, this study highlights the impact of mesh size selection and turbulence modeling on CFD-based performance analysis of two-stroke aviation engines. The results provide valuable insights for optimizing CFD modeling strategies and can serve as a reference for future research on engine design, performance enhancement, and computational accuracy improvements.