结冰对带舵面翼型流场的影响及其气动参数分析

Effect of Icing on Airfoil with Control Surface and Analysis of Aerodynamic Parameters

利用计算流体动力学方法模拟了结冰后带舵面翼型的流场变化特征,分析了不同攻角条件下升力系数与舵面偏转角的量化关系,并对比了角冰和脊状冰条件下气动导数的差异.结果表明:与干净翼型相比,结冰后带舵面翼型的升力系数及升力系数关于舵面偏转角的变化率出现了较大降幅;舵面下偏导致的"上洗"效应将会加大冰型对流场的干扰,角冰引起的流动分离尺度受舵面偏转角的影响较大,且随着来流攻角增加而愈加明显;脊状冰可使翼型上表面产生大范围的流动分离,带舵面翼型的失速偏转角大幅提前,升力系数关于舵面偏转角的变化率大幅降低;在角冰条件下,带舵面翼型的相对气动导数呈现出3个不同的变化阶段,且随着来流攻角和舵面偏转角的增加而逐级下降,而在脊状冰条件下则呈现出2个不同的变化阶段,且其降幅更明显.

The aerodynamic character of an iced-airfoil is closely related to the ice conformation, the effect of ice conformation on the flow field and the associated aerodynamic parameters of the elevator are un- known. In the present study, computational fluid dynamics （CFD） calculation was performed to simulate the flow features around an iced airfoil with control surface. Quantitative analyses were conducted to reveal the relations between the lift coefficient and the elevator deflection under various angles of attack. Compar- ison of the change rates of the lift coefficient with respect to the deflection angle was also given between the conditions of horn ice and ridged ice. The result indicate that related to a clean airfoil, the lift coeffi- cient and its rate of change of an iced airfoil are severely degraded. The up wash effect induced by the downward deflection of the elevator aggravates the disturbance of the flow field caused by horn ice. In comparison with horn ice, flow over ridged ice separates more extensively in the upper surface of the tail, resulting in a smaller stall angle and a severe degradation of the derivative of lift coefficient to the deflec- tion of the elevator. A three-step plunge of the relative aerodynamic derivative ratio is found to be a conse- quence of the increase of angle of attack and the elevator deflection for a horn-ice airfoil, while a two-step plunge with greater declination rates is observed for a ridged-ice airfoil.