湿滑跑道飞机着陆轮胎-水膜-道面相互作用

基于飞机在湿滑跑道着陆时轮胎-水膜-道面相互作用流体力学平衡,得到道面积水水膜厚度、飞机行驶速度和轮胎花纹沟槽深度为动水压强的主要影响因素。以波音737-800的主轮胎为主要研究对象,建立轮胎-水膜-道面相互作用三维模型,基于Fluent软件建立三者相互作用有限元分析模型,采用流体体积函数(VOF)法获得轮胎迎水面水流分布情况和平均动水压强,利用上述有限元模型对动水压强影响因素进行规律性分析,得出动水压强的显著影响因素为道面积水水膜厚度和飞机行驶速度,动水压强与水膜厚度及行驶速度呈正相关,水膜厚度大于3 mm时水膜产生的动水压强增长较快,等于12 mm时动水压强达到并超过胎压(1.47 MPa),存在滑水风险。行驶速度小于100 km/h时,动水压强值小于胎压,不存在滑水风险。基于上述分析结果建立动水压强与水膜厚度、行驶速度和轮胎花纹沟槽深度之间的相关关系式,考虑着陆升力的影响,获得不同降雨条件下波音737-800临界滑水速度及着陆距离延长值,为飞机着陆安全行驶提供重要理论依据。

Aircraft tire-water film-pavement interaction on wet pavement in landing

Based on hydrodynamic equilibrium equations of aircraft tire-water film-wet pavement interaction during the aircraft landing on the wet pavement,main influence factors of hydrodynamic pressures in tirewater film interaction were obtained.They are water film thickness,aircraft's taxiing speed and tire tread depth.On the basis of this result,three-dimensional solid model of tire-water film-pavement was established,in which the main tire of Boeing 737-800 was taken as the research object here.Then the finite element analysis model was established based on Fluent software.The water distribution and average hydrodynamic pressures on water attaining surface of the tire were obtained by volume of fluid (VOF) method and three main influence factors of hydrodynamic pressure were analyzed by above finite element model.Some conclusions can be drawn as follows.Water film thickness and taxiing speed of aircraft are two outstanding influence factors of hydrodynamic pressure and the hydrodynamic pressure linearly increases with the increase of water film and aircraft's taxiing speed.The hydrodynamic pressure increases faster at a water film thickness above 3 mm,and at the water film thickness of 12 mm,the hydrodynamic pressure reaches and exceeds the tire pressure (1.47 MPa),which leads to hydroplaning of the aircraft's tire.When the taxiing velocity is less than 100 km/h,the hydrodynamic pressure is less than the tire pressure which means no hydroplaning risk for the aircraft.Based on the above analysis results,relational expression between the hydrodynamic pressure and water film thickness,aircraft's taxiing speed and tire tread depth was established.Considering the lift force during landing,the critical hydroplaning speeds and the length increment of landing distance of Boeing 737-800 were obtained under different rainfall conditions to provide important theoretical foundations for landing and safe taxiing of the aircraft.