Aerodynamic Research for the Next Generation Supersonic Transport

本文对下一代超音速运输机的气动力问题进行了研究，得到了以下结果.为了高效、准确地评估飞机的气动性能，开发了一套基于非结构网格的CFD程序。其中包括基于CAD数据的面/体网格生成方法和非结构网格上的隐式时间积分方法.应用CFD程序计算了NAL实验超音速飞机上升段的气动力系数。数值计算结果揭示了跨音速飞行过程中产生高升力的原因.采用新发展的重叠网格法，对NAL实验超音速飞机与火箭助推器的分离过程进行了数值模拟，得到了分离过程中的气动力系数。该方案是一种很有前途的方法来评估飞机的动态稳定性， ...更多信息 嗯。为研究超音速运输机的起飞/着陆性能，采用自适应加密和涡心识别技术，建立了一种计算三角翼涡控流场的数值方法。结果表明，该格式能有效地预测大迎角下的涡破裂.将原来为跨音速机翼而发展的反设计方法推广到超音速机翼。利用该程序对NAL实验超音速飞机的主翼进行了设计，实现了机翼上表面自然层流的扩大，以提高升阻比.采用非结构网格方法，开发了一种有效的伴随优化程序，并将其用于机翼、机翼-机身、机翼-机身-短舱组合体的气动外形优化，以及机翼-机身组合体跨音速巡航时的襟翼角优化。提出了一种改进的多目标遗传算法，并将其应用于超声速机翼设计。考虑了四个设计目标：超音速和跨音速巡航条件下的气动阻力最小化以及俯仰力矩和根部弯矩最小化。设计结果表明，一种新型的“箭翼”布局在各项设计目标上都具有良好的性能。少

In this study, aerodynamic problems related to the next generation supersonic transport have been investigated and the following results were obtained.1. A CFD code based on the unstructured grid to efficiently and accurately evaluate the aerodynamic performance of airplanes was developed. This includes several new schemes such as the surface/volume grid generation methods using the CAD data and the implicit time integration on unstructured grid.2. The CFD code was applied to evaluate the aerodynamic coefficients of the NAL experimental supersonic airplane in ascent flight. Numerical result revealed the cause of the high lift production during the transonic flight regime.3. The separation process of the NAL experimental supersonic airplane from the rocket booster was numerically simulated and the aerodynamic coefficients during the separation were obtained by a newly developed overset grid method. This scheme is a promising approach to evaluate the dynamic stability of the airplane as … More well.4. For aerodynamic investigations of the takeoff/landing performance of a supersonic transport, a numerical scheme to predict vortex-dominated flows over delta wings were developed using the adaptive refinement and the vortex-center identification. This scheme was shown to be effective to accurately predict the vortex breakdown at high angle of attack.5. An inverse design method originally developed for transonic wings was extended to supersonic wings. With this code, the main wing of the NAL experimental supersonic airplane was designed to realize the enlarged natural laminar flow on the upper surface of the wing for improved L/D performance.6. An efficient adjoint optimization code has been developed using the unstructured grid approach, The resulting code has been used for aerodynamic shape optimization problems of wing alone, wing-fuselage, and wing-fuselage-nacelle configurations, as well as flap angle optimization on the wing-fuselage configuration at transonic cruise.7. An improved multiobjective genetic algorithm has been developed and applied to the supersonic wing design. Four design objectives were considered : minimizations of aerodynamic drag both at supersonic and transonic cruise conditions as well as minimizations of pitching moment and root-bending moment. The design results indicate that a new type of "arrow wing" configuration has good performances in all design objectives. Less