后体参数对运输机后体阻力的影响

Effects of Geometry Parameters on Drag about Afterbodies of Transport Aircraft

出于实际使用需求的考虑,运输机后体通常设计成上翘收缩的外形.这种外形会引起机身尾部出现比较强的负压区,使得飞机阻力大大增加.因此,通过运输机后体外形优化设计进行减阻是运输机减阻研究中重要的内容.选用典型上翘后体运输机的单独机身外形模型,采用外式张线天平测力和CFD数值模拟相结合的方法,分别研究了后体收缩比和后体上翘角两个主要的后体几何参数对阻力系数的影响.研究结果表明:阻力系数随后体收缩比的增大而增大,后体上翘角对阻力系数的影响与迎角相关;收缩比和上翘角对摩擦阻力系数影响较小,阻力系数的变化主要来源于收缩比和上翘角对压差阻力系数的影响;外式张线天平可以测量出后体参数变化引起的微小阻力差量,因此可以用于开展后体试验研究.

From the aim of practical using requirement, the afterbody of transport aircraft was designed as upswept and contractive The configuration will cause strong negative pressure on rear fuselage, and the drag of aircraft will greatly increase. So, the optimum design of afterbodies is important to drag reduction of transport aircraft. The drag of afterbodies for transport aircraft was investigated by force measurement test and computer simulation, using single fuselage model of transport aircraft with typical upswept afterbody, in order to study effects of contraction ratio and upswept angle on drag coefficient of afterbodies. The results show that the drag coefficient of afterbodies increases with increasing contraction ratio, the effects of upswept angle on drag coefficient of afterbodies are related with angle of attack. The friction drag coefficient increases inconspicuously with increasing contraction ratio and upswept angle. The variation of drag coefficient of afterbodies is mainly due to the effects of contraction ratio and upswept angle on pressure drag coefficient. The tiny differences of drag coefficient due to the varieties of geometry parameters of afterbodies can be measured by external wire balance. So, external wire balance can be used for the test of afterbodies.