一种基于水滴收集量代理模型的结冰试飞空域确定方法

Icing test flight area determination method based on surrogated model of water droplet collection

针对自然结冰试飞空域确定时使用的结冰指数只能给出结冰概率和结冰等级的问题,提出一种新的方法。通过对美国联邦航空条例(FAR)25部附录C连续最大结冰条件采样,对采样点进行空气流场和水滴撞击特性求解,获得不同工况的水滴收集量;基于POD(Proper Orthogonal Decomposition)和Kriging构建水滴收集量代理模型;使用WRF(Weather Research and Forecasting)对目标区域进行气象模拟,获得温度以及液态水含量分布;使用代理模型对目标区域内水滴收集量进行预测,以中度结冰强度对目标区域进行划分;最后,针对2种飞行速度对试飞空域的影响进行研究。结果表明:代理模型能够很好地预测温度、液态水含量、水滴中值体积直径、高度以及速度对水滴收集量的影响;WRF获得的目标区域的温度、液态水含量与观测值符合良好;基于代理模型可快速获得目标区域水滴收集量分布及随时间的变化,还可获得适合自然结冰试飞的目标区域及结冰速度;飞行速度的增加使得水滴收集量增加,进而引起试飞空域的变化。本文对结冰试飞空域确定具有一定参考意义。

In response to the problem that the icing index used in natural icing test flight area determination can only provide the icing probability and icing level,a new method is proposed.By sampling the continuous maximum icing conditions in Appendix C of Federal Aviation Regulations(FAR)Part 25,the air flow field and water droplet impingement characteristics were solved to obtain the water droplet collection amount for the sampling points.The surrogated model of the water droplet collection amount was constructed based on Proper Orthogonal Decomposition(POD)and Kriging.The weather simulation of the target area was performed using WRF(Weather Research and Forecasting)to obtain the temperature and the liquid water content.The water droplet collection amount over the target area was predicted with the surrogated model and the target area was divided by the moderate icing intensity.The results show that:the surrogated model can predict the effects of temperature,liquid water content,median volume diameter,height and flight speed on water droplet collection amount correctly;the temperature and the liquid water content of the target area obtained by WRF are in good agreement with the observed values;the surrogated model can quickly obtain the distribution of the water droplet collection amount over the target area and its variation with time;the suitable natural icing test flight area and the icing rate are determined.The growth of the flight speed makes the water droplet collection amount increase and causes the variation of the icing test flight area.This paper has some reference significance for the determination of the icing test flights area.