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Estimation of Performance Airspeeds for High-Bypass Turbofans Equipped Transport-Category Airplanes

机译：配备高旁路涡轮喷气发动机的运输类飞机的性能空速估算

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Conventional Mach-independent subsonic drag polar does not replicate the real airplane drag characteristics exactly and especially not in the drag-divergence region due to shock-induced transonic wave drag. High-bypass turbofan thrust is a complicated function of many parameters that eludes accurate predictions for the entire operating envelope and must be experimentally verified. Fuel laws are also complicated functions of many parameters which make optimization and economic analysis difficult and uncertain in the conceptual design phase. Nevertheless, mathematical models and predictions have its important place in aircraft development, design, and optimization. In this work, airspeed-dependent turbofan thrust and the new fuel-law model were used in combination with an airplane polynomial drag model to estimate important performance speeds. Except for the airframe-only dependent control airspeeds, all performance speeds are airframe powerplant dependent. In all analytical considerations one ends up with polynomials of the 4th order that have no closed-form solutions. A real positive-root seeking numerical procedure based on the family of Newton-Raphson methods was used to extract performance airspeeds for variable in-flight weights and altitudes in the ISA troposphere. Extensive testing of the accuracy and convergence of the Newton-Raphson nonlinear equation solvers was conducted before performance speed calculations. A fictitious long-range wide-body transport-category airplane was modeled in combination with a pair of high-bypass and ultra-high bypass ratio flat-rated turbofans. Procedure employed here can be easily extended to cases when fitted, measured drag and thrust data is given in arbitrary polynomial forms. Sensitivity analysis is performed on minimum-drag airspeed and maximum aerodynamic efficiency. Transonic wave drag considerations are introduced.
机译：传统的与马赫无关的亚音速阻力极不能完全复制真实的飞机阻力特性，尤其是在由于激振引起的跨音速阻力而在阻力发散区域中尤其如此。高旁路涡轮风扇推力是许多参数的复杂功能，无法对整个运行范围进行准确的预测，必须进行实验验证。燃料定律也是许多参数的复杂函数，这使得优化和经济分析在概念设计阶段变得困难而不确定。尽管如此，数学模型和预测在飞机开发，设计和优化中仍具有重要地位。在这项工作中，将空速相关的涡扇推力和新的燃料定律模型与飞机多项式阻力模型结合使用，以估算重要的性能速度。除了仅取决于机身的控制空速之外，所有性能速度都取决于机身动力装置。在所有分析方面，最终都得到了四阶多项式，这些多项式没有闭合形式的解。基于牛顿-拉夫森方法族的真实的正求根数值程序被用于提取ISA对流层中可变的飞行重量和高度的性能空速。在计算性能速度之前，对牛顿-拉夫森非线性方程求解器的准确性和收敛性进行了广泛的测试。一个虚拟的远程宽体运输类飞机是结合一对高旁路和超高旁路比率的平置涡轮风扇进行建模的。此处采用的程序可以轻松扩展到拟合的情况，以任意多项式形式给出测量的阻力和推力数据。对最小阻力空速和最大空气动力学效率进行灵敏度分析。介绍了跨声波阻力的考虑因素。

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    Daidzic, Nihad E;

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