尾翼对民机后体流动特性的影响

Influence of empennage on flow over upswept after-body

在1．5m低速风洞中采用表面油流、烟线／激光片光显示和部件测力等实验方法对2种民机布局后体的绕流流型和气动特性进行了研究．实验的风速为40m／s，雷诺数为1．191×10^5，迎角范围为-10°～20°，实验结果表明：随着迎角由负到正的变化，2种布局模型后体绕流都经历了上分离-无分离-下分离流型的变化，分离流型属开式分离并由尾部起始向机身发展；小迎角下2种布局模型后体阻力的差别主要由尾翼的摩擦阻力引起，而较大迎角下尾翼绕流分离引起的压差阻力起主要作用；垂尾分离随迎角增加而不断减弱，从而导致正常式布局后体阻力随迎角变化表现为非对称．

To provide a foundation of upswept after fuselage drag reduction, the flow patterns and aerodynamic characteristics over two upswept rear fuselages with and without empennages were investigated in a I. 5 by 1.5 meters low speed wind tunnel by the methods of oil flow, smoke wire/laser and force measurement. The results were obtained at 40 m/s and Reynolds number of l. 191 × 10^5 at angles of attack ranging from - 10° to 20°. With the attack angle increasing from negative to positive, the flow over rear fuselage, which is developed from the end of body to forward, goes through three kinds of open separation mode, namely up-separation, non-separation and down-separation. The drag difference between the after-bodies with and without empennages is due to the friction drag on empennages for non-separation mode and is due to separation on the empennages at higher attack angle. The drag reduction caused by separation weakening on vertical tail results in drag increasing slowly with the increase of the positive attack angle.