民航发动机凝结尾迹特征数值模拟

Numerical simulation on condensation tail characteristics of a civil aviation engine

为了研究民航发动机喷气射流及其形成的凝结尾迹,建立双流体凝结模型,采用计算流体动力学(computational fluid dynamics,CFD)数值模拟方法,分析民航发动机射流流场特征,并对不同温度和相对湿度(relative humidity,RH)条件下凝结尾迹空间范围和凝结参数进行对比。结果表明:喷气射流在离开喷管较短的距离内膨胀剧烈,约20 m之后流向截面参数较为均匀,压力膨胀为环境压力。温度偏差对凝结尾迹的宽度和长度影响显著,当温度高于该高度国际标准大气(international standard atmosphere,ISA)温度条件时,凝结尾迹的持续范围有限;温度低于ISA温度条件时,凝结尾迹可持续100 m以上,且凝结参数可达到稳定状态。相对湿度对凝结尾迹的影响程度低于温度偏差,相对湿度主要影响凝结尾迹的宽度和液滴平均半径。

In order to study the jet flowfield and the condensation tail of a civil aviation engine,a two-fluid condensation model was established.Using computational fluid dynamics(CFD)numerical simulation method,characteristics of the jet flowfield were analyzed,and the space range and condensation parameters of the condensation tail were compared under different temperature deviations and relative humidity(RH).The results show that the air jet expands rapidly within a short distance from the nozzle exit.After about 20 meters,the parameters along flow section are relatively uniform,and the pressure expands to the environmental pressure.The temperature deviation seriously affects the width and length of the condensation tail.The trail range is limited above international standard atmosphere(ISA)temperature conditions.When the temperature is lower than the ISA temperature condition,the tail can persist more than 100 meters,and the condensation parameters can be more stable.The influence of relative humidity on the condensation tail is lower than ISA deviation.Relative humidity mainly affects the width of the tail and the mean radius of the droplet.