冰脱落对电热除冰传热特性的影响研究

Study on effect of ice shedding on heat transfer characteristics of electrothermal aircraft deicing

冰脱落对电热除冰传热特性的影响是电热除冰过程中的重要特征。采用有限体积法和混合网格技术,基于热焓方法将传统的相变传热模型应用到电热除冰计算中,研究了冰脱落对电热除冰传热特性的影响,主要研究了加热模式和加热单元间隔对除冰结构传热特性的影响。研究发现:无间隔除冰单元是有间隔除冰单元的特殊情况,其蒙皮表面温度历程在本质上是一致的。冰脱落后,无间隔除冰单元蒙皮表面温度开始剧烈上升然后逐渐缓慢上升。而对于有间隔除冰单元,随着间隔上加热功率的降低,温升过程逐渐缓和。单元间隔的加热功率降低到一定程度时,表面温度出现温降过程。当传递到蒙皮表面的热量和对流换热带走的热量差逐渐趋于稳定时,表面温度又开始逐渐稳定的上升。

The effect of ice shedding on heat transfer characteristics is one of the important aspects of electrothermal aircraft deicing. Based on the enthalpy method, the traditional phase-change model is applied to the simulation of aircraft electrothermal deicing with a finite volume method on hybrid grids. The effects of ice shedding on heat transfer characteristics are studied, including the effects of heating manner and the heater gap width of deicing structure. The numerical results demonstrate that deicer without gap is a special case of those with gaps. The skin surface temperature history is essentially similar. After ice shedding, the skin surface temperature of deicer without gap increases dramatically at the early stage, and then the increasing speed slows down gradually. For the deicer with gaps, the temperature increment gradually relaxes with the heating power density in the gap decreasing. When the heating power density decreases to a certain value, the temperature drop will occur. If the difference between the heat flux delivered to the skin surface and the removed heat flux from convection tends to be constant gradually, the skin surface temperature will rise up slowly.