民机风洞试验半模垫板高度对气动特性的影响

半模作为提高大型商用飞机风洞试验雷诺数的一种模拟手段而被广泛应用。首先回顾了半模试验的模拟方式及其优劣,进而选取当前发展趋势的附面层垫板作为研究对象,采用数值模拟研究了垫板高度变化对气动特性影响的内在机理。数值模拟结果和试验吻合较好,数值计算采用速度分布入口可以较好模拟风洞核心段边界层厚度,计算值和试验值更加接近;垫板高度的增加使得升力系数增加、阻力系数减小及俯仰力矩系数增加;垫板在机翼上游区引起的上洗使得机翼沿展向各剖面当地迎角增加5%、动压增加1%,从而使得机翼上翼面压力分布朝负值方向移动。有别于以往认为垫板的洗流只影响内侧机翼,结果表明垫板影响范围扩展至全翼展,当地迎角的增加是主要影响因素,垫板对机翼展向各剖面影响量值不一致,对内侧机翼影响较大。所得结论可更好用于民机半模风洞试验的开展,具有一定的工程实用性。

Effects of half model peniche height on civil aircraft aerodynamic characteristics in wind tunnel test

Half model simulation,as a method to get higher test Reynolds number,is widely used in the design of large commercial transport aircrafts.This paper reviews the pros and cons of the half model simulation,and then studies the peniche simulation which is widely accepted.The mechanism of the effect of the peniche height on aerodynamic characteristics is studied.CFD simulation is found to agree well with the experimental result.The boundary layer thickness of the middle of the wind tunnel test section can be better simulated by using velocity distribution inlet condition,and the simulation results are more close to the experimental results.With the increase of peniche height,lift coefficient increases,drag coefficient decreases and pitching moment coefficient increases.The upwash induced by peniche in the coming flow in front of the wing increases the local angle of attack by 5％ and dynamic pressure by 1％ along the full span,thus making the pressure distribution more negative.Different from the traditional concepts that the upwash induced by peniche can only affect the inboard wing,results show that the peniche effects extend to the whole span.The prime factor is the increase of the local angle of attack.The effects of peniche heights vary with the spanwise location,having more impacts on the inboard wing.The results can be better used in the half model wind tunnel test with certain engineering practicability.