Combustion and Emission Characteristics of Compression- Ignition Aero Piston Engine at Different Altitudes

Research on combustion and emission characteristics of compression-ignition aero piston engine at different altitudes will be conducive to further optimizing the propulsion system of navigable aircraft. Through the atmospheric pressure simulation test bench, the combustion and emission tests of compression-ignition aero piston engine were carried out at three different altitudes (10, 1000 and 1920m), and the variation rules of combustion and emission pollutants under these altitudes were obtained. The results show that with the increasing altitude and the decreasing atmospheric pressure, the intake mass flow rate of the aero piston engine significantly decreases, and the excess air coefficient and the effective thermal efficiency also slightly reduce, but the effective fuel consumption rate raises. In addition, at the same running point of engine, the peak combustion pressure decreases, the ignition delay period is prolonged, the start point of combustion is postponed, the combustion duration is basically extended, the maximum average combustion temperature and the NOx, HC and smoke emissions of the aero engine increase. When the altitude and engine load increase, the smoke emission firstly decreases and then increases. The increment of CO emission is obvious at the small-load and large-load of engine, but it remains unchanged near the medium-load. © 2022, Editorial Department of Journal of Propulsion Technology. All right reserved.