涡扇发动机短舱结冰试验相似方法

通过分析短舱表面结冰缩比试验相似要求,在保证绕流流场、水滴撞击特性和结冰冰型相似的基础上,分别采用基于气流雷诺数,气流韦伯数和水滴韦伯数3种速度选取方法建立了试验相似准则。利用该准则获得了明冰和霜冰条件下涡扇发动机短舱1/2缩比模型的结冰试验参数,开展了短舱进气道表面结冰冰型预测,对参考模型和缩比模型表面过冷水滴撞击特性、结冰特性、溢流水分布特性进行了分析。结果表明:采用基于气流韦伯数和水滴韦伯数速度选取方法的相似准则,在明冰和霜冰条件下均能保证缩比模型与参考模型表面水滴撞击特性相似,且相似性不受结冰温度影响；溢流水变化趋势与参考模型相似,流动极限相近；缩比模型表面冰型均与参考模型相似,该方法能够为短舱结冰试验参数选取提供依据。 

Scaling method of turbofan engine nacelle under icing test

In order to eliminate the constrains of engine icing test on experimental ability and space, an icing scaling law of turbofan engine nacelle icing test was established based on similar requirements such as the airflow field, water droplet impingement and ice accretion characteristics. And there were three airflow velocity selections based on airflow Reynolds number, airflow Weber number and water droplet Weber number respectively, and these three velocity selections can be used to reflect different influencing parameters on icing similarity. The glaze and rime ice accretion conditions of 1/2 sub-scale turbofan engine nacelle model were obtained by this scaling law. And the ice prediction on turbofan nacelle inlet was carried out with numerical simulation, and the similarities of water droplet impingement, ice accretion and runback water characteristics were analysed. Results show that the scaling law based on airflow Weber number and water droplet Weber number can better ensure the similarity of the droplets impingement on the surface of the scale model and the reference model under the glaze ice and rime ice conditions, and the similarity is not affected by the freezing temperature. The variation and limit of the runback water is similar to the reference model. Under different icing conditions, the surface ice accretion of scale model is similar to the reference, and this scaling law can provide a good basis for the subscale nacelle icing test.