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首页> 外文学位 >Minimum Power Requirements and Optimal Rotor Design for Conventional, Compound, and Coaxial Helicopters Using Higher Harmonic Control.
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Minimum Power Requirements and Optimal Rotor Design for Conventional, Compound, and Coaxial Helicopters Using Higher Harmonic Control.

机译：使用高级谐波控制的常规，复合和同轴直升机的最低功率要求和最佳旋翼设计。

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摘要

This thesis presents a method for computing the optimal aerodynamic performance of conventional, compound, and coaxial helicopters in trimmed forward flight with a limited set of design variables, including the blade's radial twist and chord distributions and conventional and higher harmonic blade pitch control. The optimal design problem, which is cast as a variational statement, minimizes the sum of the induced and viscous power required to develop a prescribed lift and/or thrust. The variational statement is discretized and solved efficiently using a vortex-lattice technique. We present two variants of the analysis. In the first, the sectional blade aerodynamics are modeled using a linear lift curve and a quadratic drag polar, and flow angles are assumed to be small. The result is a quadratic programming problem that yields a linear set of equations to solve for the unknown optimal design variables. In the second approach, the problem is cast as a constrained nonlinear optimization problem, which is solved using Newton iteration. This approach, which accounts for realistic lift and drag coefficients including the effects of stall and the attendant increase in drag at high angles of attack, is capable of optimizing the blade planform in addition to the radial twist distribution and conventional and higher harmonic blade pitch control. We show that for conventional rotors, coaxial counterrotating rotors, and a wing-rotor compound, using radially varying twist and chord distributions and higher harmonic blade pitch control can produce significant reductions in required power, especially at high advance ratios.
机译：本文提出了一种在有限的设计变量集（包括叶片的径向扭曲和弦分布以及常规和高次谐波叶片桨距控制）的有限设计变量下计算常规，复合和同轴直升机在修剪前向飞行中最佳气动性能的方法。最佳设计问题可以看作是变化的陈述，它可以最大限度地减小产生规定的升力和/或推力所需的感应功率和粘性功率之和。使用涡旋格技术可以离散化并有效地解决变分陈述。我们提出了两种分析方法。首先，使用线性升力曲线和二次阻力极来模拟叶片截面的空气动力学特性，并假设流动角较小。结果是二次规划问题，产生了线性方程组以解决未知的最佳设计变量。在第二种方法中，该问题被转换为约束非线性优化问题，可以使用牛顿迭代法求解。这种方法考虑了实际的升力和阻力系数，包括失速的影响以及随之而来的高攻角阻力的增加，除了径向扭曲分布以及常规和更高次谐波的桨距控制外，还可以优化桨叶平面形状。 。我们显示出，对于常规转子，同轴反向旋转转子和机翼-转子复合件，使用径向变化的扭曲和弦分布以及更高的谐波叶片螺距控制，可以显着降低所需功率，特别是在高传动比的情况下。

著录项

  • 作者

    Giovanetti, Eli B.;

  • 作者单位

    Duke University.;

  • 授予单位 Duke University.;
  • 学科 Engineering Mechanical.;Engineering Aerospace.
  • 学位 M.S.
  • 年度 2013
  • 页码 179 p.
  • 总页数 179
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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