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SOLUTION TO OPTIMIZE THE AIRFOILS SHAPES PLACED INTO A SUPERSONIC VISCOUS FLOW

机译:优化放置在超音速粘性流中的机翼形状的解决方案

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To improve the airfoils performances placed in supersonic flow is proposed a method of optimization for their shapes, in order to minimize the effect of the landing vortices. The theoretical modeling starts with the Navier-Stokes equations applied for thin layers, supplemented with additional conditions related to the profile shape. For a proper estimation of efficiency and responses at different flow regime's conditions, were considered four aerodynamics airfoils, with different shapes and functioning characteristics. Two of them are special shapes of supersonic profiles and the other two deduced by theoretical assessments with an efficient behavior at high Reynolds numbers. The main purpose of this selection was to identify the essential aspects needed to be considered in numerical modeling of the airfoil's wing shapes, as to assure an optimization of their behavior for different flow conditions. In the supersonic flow, the cross-sections of the wings are thin profiles, mainly symmetric, as to reduce the drag coefficient and to maximize, as possible, the lift coefficient. A supplementary method for the shape calculation of the aerodynamic profiles with small curvature, based on the Fredholm integral equation of the second kind, with a good behavior in the supersonic flow, is presented. Some aspects referring to unsteady flows and air compressibility are considered, as to simulate as much as possible the real, natural conditions. All profiles were tested, firstly, into a subsonic wind tunnel at incidences between 0° - 4° for different values of wind velocity, and secondly, into a supersonic wind tunnel, at the same incidences. The objective was to better understand and analyze the main factors, which influence the aerodynamic of shapes with curvature, and to assure an optimization of their behavior. The purpose of testing these profiles was to estimate a solution to improve the main characteristics, especially into the trailing and leading edges zones. There were also considered the effects of the attack angle, the influence of the wind velocity, air viscosity, and the shape's curvature, on the vortices development. The obtained results allow a better functioning in supersonic flow regime, by eliminating the adverse pressure gradient and the boundary layer separation, assuring an optimum behavior especially into the leading edge zone.
机译:为了改善放置在超音速流动的翼型,提出了一种针对它们的形状进行优化的方法,以便最小化着陆涡流的效果。理论建模从施加的薄层的Navier-Stokes方程开始,补充有与轮廓形状相关的附加条件。为了适当估计不同流动制度条件下的效率和响应,被认为是四个空气动力学翼型,具有不同的形状和功能特性。其中两个是超音速曲线的特殊形状,另外两个由高雷诺数的有效行为推导出来。该选择的主要目的是确定在翼型翼形状的数值建模中考虑所需的基本方面,以确保它们对不同流动条件的行为进行优化。在超音速流动中,翼的横截面是薄的轮廓,主要是对称的,从而减小拖曳系数并尽可能最大化提升系数。提出了一种基于第二类的Fredholm积分方程的小曲率的空气动力学谱的形状计算的补充方法,具有超声波流动的良好行为。参考不稳定流和空气可压缩性的一些方面被认为是尽可能地模拟真实的自然条件。所有型材首先被测试到亚音速风隧道中,以在相同的公告中以0° - 4°的出发,在0°-4°的情况下,对于不同的风速值,其进入超声波风洞。目的是更好地理解和分析主要因素,影响具有曲率的形状的空气动力学,并确保它们的行为优化。测试这些简档的目的是估算改善主要特征的解决方案,尤其是在尾部和前沿区域。还考虑了攻击角,风速,空气粘度和形状曲率的影响,在涡流发育中的影响。通过消除不利的压力梯度和边界层分离,可以在超音速度和边界层分离中允许获得的结果更好地运行,确保了特别是在前缘区域中的最佳行为。

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