Effects of combustion and performance of compression-ignition aero piston engine with different nozzle parameters in the high-altitude environment

Taking a four-cylinder compression-ignition aero kerosene piston engine as the research model, AMESim (advanced modeling environment for performing simulation of engineering systems) simulation software was used to establish the engine model, and the simulation model was verified with the data collected from the engine bench test. In the high-altitude environment, the influence relationship of the combustion characteristic, performances and NOx emission characteristics of the engine between different nozzles and diameters' injector schemes under the takeoff condition and the maximum cruising condition of the aircraft was simulated and analyzed. The results showed that, under steady-state conditions, the maximum combustion pressure and temperature increased with the increasing numbers of nozzle-hole, and the heat release rates also increased rapidly with the peak value. In addition, when the premixed-combustion in the cylinder was strengthened and the combustion starting point was advanced, the ignition delay period and combustion duration were shortened, the combustion center moved forward, and the cycling thermal efficiency was higher, but the NOx emission was increased. Under the takeoff condition of the aircraft with the transient altitude change, multi-holes and small-diameters of fuel nozzle were conducive to the recovery of engine power in the high-altitude environment, improving the dynamics and the continuous flying performance of aircraft.