定常吹气对无缝襟翼翼型地面效应影响的数值模拟

随着对生产成本、性能和可靠性、环境要求的不断提高,未来运输类飞机的发展趋势是具有更大的载重、更短的起降距离、更低的污染排放和噪声,因此迫切需要采用更高效和简单的增升和控制技术,而采用狭缝吹气的主动流动控制增强升力的方式已经被证明是最值得研究推广的应用技术之一。而在分析飞机起降性能时,必须要考虑到地面效应的影响,因此有必要对采用吹气进行增升的翼型地面效应进行研究。通过数值模拟方法研究了定常吹气对某无缝襟翼翼型地面效应的影响,研究表明,近地面在襟翼前缘施加吹气控制后,与远地面施加定常吹气控制相比,翼型升力线斜率和升力明显降低;小迎角下,动量系数为0.005时,升力随着距地高度的减小先减小后增加,动量系数增加到0.01后,升力随着距地高度的减小而减小;无缝襟翼翼型在不同动量系数和不同距地高度时出现的不同程度升力减小的现象,能直接影响飞机的起降性能,是采用吹气控制进行增升设计时必须考虑的因素。

Numerical simulation of effect of steady blowing slot-less flap airfoil in ground effect

With growing requirements for the manufacturing cost,performance and reliability,and environment,the transport aircraft with bigger payload,shorter taking off and landing distance,and lower fuel consumption and aerodynamic noise is the development object of the future transport aircraft.Therefore,simple and efficient lift enhancement method is urgently needed.The method using blowing to enhance the lift is proved to be one of the most promising technologies.In the analysis of the performance of taking off and landing,ground effect must be considered,and it is thus essential to investigate the ground effect of the airfoil using blowing to enhance lift.The aerodynamic characteristics of slot-less flap airfoil with steady blowing in ground effect are investigated by numerical simulation.The results show that the lift and lift slope of the airfoil decrease obviously with steady blowing at small ride height compared with that far from the ground.The results also indicate that at small angles of attack,the lift increases firstly and then decreases with the decrease of ride height when blowing momentum coefficient is 0.005,but the lift monotonously decreases with the decrease of ride height when blowing momentum coefficient is 0.01.The phenomenon that the lift of the slot-less flap airfoil varies with the moment coefficients and the ride heights can directly affect the performance of taking off and landing,so it must be taken into consideration when applying blowing to increase the lift.