Analysis of Combustion Characteristics and Power Performance of an Opposed-Piston Two-Stroke Unmanned Aerial Vehicles Engine

As the mainstream power system for unmanned aerial vehicles (UAVs), enhancing the performance of two-stroke engines is of paramount importance. This study developed a computational fluid dynamics (CFD) numerical model of the in-cylinder flow and combustion process in an opposed-piston two-stroke UAV engine. It focused on the influence patterns of rotational speed and injection timing on the engine’s combustion characteristics and power output. Research scenarios were set for typical rotational speed conditions (1000–3000 r/min) and injection timing conditions (BTDC 35–15 °CA). Results indicate that overall increasing engine speed while retarding the injection timing yields improved combustion efficiency and power output. At an engine speed of 2000 r/min, the ignition delay is reduced, and with an injection timing of −20 °CA, the engine shows a moderate process of combustion and heat release. Under these operating conditions, the combustion is characterized by a moderate heat release rate, relatively high cylinder pressure, enhanced indicated work and power, and comparatively low cylinder temperatures. Considering all performance aspects, employing an engine speed of 2000 r/min and an injection timing of −20 °CA yields superior combustion and power performance.