Spray and Ignition in the Five-Nozzle Combustor of an Aero-Engine
The multi-head ignition is crucial for the development of lean pre-mixed pre-vaporized(LPP)combus-tors in aircraft engines.A visualized experimental combustion system with five linear arrays of LPP nozzles was built to investigate the ignition mechanism of the flame from the initial stage to the complete propagation in the combustion chamber.By using a high-repetition-rate and high-energy burst laser system and combining the 10 Hz PLIF/PMIE,10 kHz PIV and 2 kHz OH* chemiluminescence high-speed imaging techniques,the influence of airflow(110-250 g/s)and fuel-air ratio(0.032-0.066)on the characteristics of the spray field and the ignition flame was analyzed.Results indicate that the variation in fuel pressure and airflow significantly affects the distribu-tion of MIE and LIF signals in the spray field and the atomization effect of the fuel.With an increase of fuel pres-sure,the size and number density of spray droplets increase,while the fluctuation in droplet velocity weakens,leading to a reduction in turbulent kinetic energy.Conversely,an increase in air flow promotes fuel atomization,reduces the velocity difference between droplets,and consequently decreases turbulent kinetic energy.During the ignition and flame propagation processes,the flow rates of air and fuel are critical parameters.Higher flow rates(e.g.250 g/s)result in rapid flame propagation,allowing flames of multiple heads to be quickly ignited within 150 ms,whereas lower flow rates(e.g.200 g/s)lead to a slower flame propagation,a multi-head flame time longer than 500 ms,and a risk of incomplete ignition.
aeroengine ignitionmulti-head combustorlaser diagnosisatomization and evaporationlean pre-mixed pre-vaporized,LPP
万方数据
维普
