不同海拔下压燃式航空活塞发动机的燃烧与排放特性

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

关键词:  航空发动机  活塞发动机  试验台架  海拔高度  燃烧特性  排放特性

Key words:  Aeroengine  Piston engine  Test bench  Altitudes  Combustion characteristic  Emission characteristic

摘要:

研究压燃式航空活塞发动机在不同海拔高度下的燃烧与排放特性，将有利于进一步优化通航飞行器的动力推进系统。通过发动机大气压力模拟试验台架，在3个不同海拔高度（10，1000，1920m）进行压燃式航空活塞发动机的燃烧与排放试验，获得了发动机的燃烧和排放污染物与海拔高度的变化规律。试验结果表明：随着海拔高度的上升，大气压力减小，航空发动机的进气质量流量降幅明显，过量空气系数和有效热效率也略有下降，但有效燃油消耗率是上升的；此外，在相同工况点出现最大燃烧压力下降，滞燃期延长，燃烧始点推迟，燃烧持续期呈延长趋势，最高平均燃烧温度增大，且发动机的NO_x，HC和碳烟排放增加。当海拔升高，发动机的负荷增大时，碳烟排放呈现出先降低后升高。在小负荷和大负荷时的CO排放增加较为明显，而中负荷附近基本保持不变。

Abstract:

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 NO_x， 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.