Research on optimization of exhaust structure and exhaust noise reduction for an aviation piston two-stroke engine

The two-stroke engine has emerged as the predominant power source for drones due to its distinctive advantages. However, the operational principles of these engines generate significant exhaust noise, which compromises both the stealth capabilities of drones and human physical and mental health. The installation of a muffler in two-stroke engines can increase back pressure within the cylinder, leading to a reduction in power output. To optimize the balance between power performance and noise reduction in two-stroke engines, this study focuses on an aviation piston two-stroke engine as the subject of investigation. By developing a comprehensive flow model of the engine, it undertakes a detailed analysis of the exhaust flow characteristics and energy properties within the exhaust pipe and muffler, which integrate the scavenging, combustion, and exhaust processes. This approach enables the identification of the dissipation pattern of exhaust energy throughout the entire flow domain. A genetic optimization algorithm is utilized to design the engine's exhaust structure, and a detailed mechanism analysis of the exhaust system was performed via 3D acoustics and fluid dynamics simulations. The findings reveal that, compared to conventional mufflers, the optimized muffler developed in this study achieves a noise reduction of 41.7 dB, while the power loss decreases from 16.6 % to 5.6 %. This research confirms the viability of employing genetic algorithms to optimize exhaust structures, offering a novel approach to the design of exhaust systems in two-stroke engines.