基于适航标准的飞机风挡加温系统控制方式研究

Research on Airworthiness-based Control Mode for Aircraft Windshield Heating System

民用飞机适航条款要求在预定运行的环境条件下风挡不应结冰或结雾,防止影响机组人员的视界。因此应确保在整个飞行过程中风挡具有足够的热量以使其外表面高于冰点,内表面不低于座舱露点温度。以适航条款为基础对风挡加温系统的设计要求进行阐述,分析影响系统设计的主要因素,包括加温方式的选择、防冰热载荷的计算和加温控制规律的确定等;利用LMS.AMESim软件建立风挡瞬态传热模型,计算某型飞机风挡在不同控制规律下其表面温度和加热功率的变化。结果表明:全功率加温式控制方式下风挡升温速率快,能将玻璃始终保持在一个较高温度,有利于系统的防冰除雾性能;占空比式加温控制方式可大幅降低对玻璃的热冲击,但由于其加热功率波动非常频繁,会对上游供电设备造成较大影响。

According to civil aircraft airworthiness standards,the windshield surface should avoid icing or fogging to ensure the pilots visual field.A reasonable heating power should be determined to keep the temperature of windshield.A summarization is made about the critical parameter of windshield heating system design,including heating method,thermal load calculation and control regulation.Based on the related aircraft,the heat transfer processes simulation of windshield is predicted and characteristics of two different heating modes are analyzed by making use of LMS.AMESim.The results demonstrate that the full heating power mode could make a high heating rate and then the windshield will remain a higher temperature,which is good for performance of anti-ice and defogging.Duty ratio heating mode could greatly reduce the thermal shock to windshield,but it also will produce significant impact on upstream equipment because of frequent change of heating power.