燃气轮机燃烧室液雾自燃延迟时间预测方法

A Prediction Method for Spray Autoignition Delay Time in Gas Turbine Combustor

针对贫油预混预蒸发燃烧室主燃级中横喷液雾现象进行研究,综合考虑RP-3航空煤油横喷液雾的雾化、蒸发和自燃过程构建自燃预测模型,基于CH基团随时间的变化规律对自燃延迟时间进行预测。结合试验测试结果对模型进行校验,并进一步分析温度、压力、流速、射流动量比等变量对自燃延迟时间的影响规律。结果表明:对于直射式喷嘴形成的横喷液雾,其下游的油气分布主要受射流动量比和流动速度的影响,射流动量比决定了液雾的总体油气比,流动速度则主要影响液滴的粒径及其蒸发时间;随着压力、射流动量比及气流速度的增加,自燃延迟时间均会缩短,相比于预混燃料液雾的自燃延迟时间受负温度效应的影响较弱。

A phenomenon of liquid jet in cross flow in fuel-lean premixed pre-evaporation combustor main stage was studied.The autoignition prediction model was constructed with considering the atomization,evaporation and autoignition process of liquid jets in cross flow for RP-3 jet fuel sprays,eventually the autoignition delay time was predicted based on the time evolution of the CH in the liquid-gas mixture.The model was validated by comparing to experimental results and was then utilized to analyze the influences of variables such as temperature,pressure,main stream velocity and liquid-to-air momentum ratio on the autoignition delay time.The results show that for liquid jet in cross flow formed by direct-injection type nozzle,its fuel-air mixing downstream is mainly affected by the liquid-to-air momentum ratio and main stream velocity,in which liquid-to-air momentum ratio determines total fuel-air ratio,while stream velocity mainly affects the droplet sizes and the related evaporation time;the autoignition delay time decrease with the increase of pressure,liquid-to-air momentum ratio and main stream velocity.The autoignition delay time of spray is less affected by the negative temperature effect compared to premixed combustibles.