热气防冰系统热载荷及引气流量制度分析

Analysis of heat load and bleed air schedule for hot air anti-icing system

飞机机翼热气防冰系统设计主要包括防冰热载荷计算、笛形管设计、防冰腔设计和防冰系统验证。以某客机机翼为例,在机翼防冰热载荷计算的基础上,分析热载荷及溢流水蒸发率结果,获得防冰引气量需求,进一步提出防冰系统随高度变化的引气流量制度,确定防冰系统严酷状态设计点。采用欧拉-欧拉两相流方法计算水滴运动和表面水滴撞击特性,建立考虑溢流水流动相变的机翼表面的能量平衡方程,计算分析机翼表面的防冰热载荷和溢流水的蒸发率。分析结果表明:同一飞行与结冰气象条件下,在防冰表面温度2~15℃范围,热载荷随着表面温度近似以线性增加;为满足防冰要求,高度较低时的状态对应的表面温度设计值较大;引气流量制度随高度变化分为3个阶段:高度小于5594.9 m时,单边流量为0.91 kg/s;高度大于6705.0 m时,单边流量为0.59 kg/s;中间高度对应流量采取两者线性插值方式。研究结果为热气防冰系统的笛行管设计及校核提供支撑。

The design of an aircraft wing anti-icing system mainly includes the anti-icing heat load calculation,piccolo tube design,anti-icing cavity design,and anti-icing system verification.This paper introduces the first part of a series study in this respect.With an aircraft wing as an example,the heat load and the runback water evaporation rate are analyzed based on the calculation of the wing anti-icing heat load,and the demand of the bleed air for anti-icing is then obtained.Furthermore,a bleed air schedule for anti-icing varying with altitude is proposed,and severe conditions for the anti-icing system design are determined.The Euler-Euler two-phase flow method is used to calculate the water droplet movement and impingement characteristics on the wing surface.The energy balance equation of the wing surface considering the phase change of runback water is then established,and the anti-icing heat load and evaporation rate of the wing surface are obtained.The results show that the heat load increases approximately linearly with the surface temperature in the range of 2~15℃under the same flight and icing condition.To meet the anti-icing requirements,the design value of the surface temperature corresponding to the lower altitude is increased.The bleed air schedule for anti-icing varying with altitude is divided into three stages:the hot air flow flux is 0.91 kg/s when the altitude is less than 18356 ft,0.59 kg/s when the altitude is higher than 21998 ft and linearly interpolated when the altitude is in between 18356 and 21998 ft.The results of this study provide valuable insight into the design and verification of the piccolo tube of hot air anti-icing systems.