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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。
Half molds are widely used as a simulation tool to improve the Reynolds number of large commercial aircraft wind tunnel tests. First of all, the simulation method of half-mold test and its advantages and disadvantages are reviewed. Then, the current development tendency of the cover plate is selected as the research object. The internal mechanism of the influence of the plate height on the aerodynamic characteristics is studied by numerical simulation. The results of numerical simulation are in good agreement with the experimental data. The numerical calculation of the velocity distribution entrance can simulate the boundary layer thickness of the core section of the wind tunnel well and the calculated values are close to the experimental values. The increase of the height of the pad increases the coefficient of drag, The pitch moment coefficient increased. The upper wash caused by the pad in the upstream of the wing caused the local angle of attack of the wing to increase by 5% at each section along the extension direction and the dynamic pressure increased by 1%. As a result, the pressure distribution on the wing surface in the negative direction mobile. Different from the previous thought that the wash flow of the pad only affects the inner wing, the result shows that the influence range of the pad extends to the span-span. The increase of the local angle of attack is the main factor, and the influence of the pad on the span Inconsistent, greater impact on the inner wing. The conclusions can be better used in civil aircraft half-mold tunnel test carried out with a certain degree of practical engineering.