中国科学院力学研究所机构知识库

高超声速飞机因具有飞行速度快、航行距离远、运输效率高等特点，是目前世界范围内研究的热点。近年来，各国相继提出了多种高超声速飞机概念。现有的高超声速气动布局主要包括升力体、乘波体、翼身组合体、翼身融合体等。这些气动布局主要通过压缩来流产生升力，同时利用机体上表面凸起用于装载。为了实现更高的升阻比，高超声速飞机通常采用采用扁平化设计，这就导致飞机的装载能力受限。高压捕获翼气动布局基于有益气动干扰在高超声速来流条件下可以同时获得较好的装载能力以及气动性能；同时，因其采用双升力面布局，在亚声速来流条件下也可以具有良好的升力特性，是一款极具前景的新型宽速域高超声速气动布局。

相较于传统气动布局，高压捕获翼构型的机体与捕获翼之间会产生复杂的气动耦合效应。研究表明，在亚声速来流条件下，与不含捕获翼的构型相比，高压捕获翼构型在较低马赫数时机体扩张段上方就会出现流动分离现象。随着来流马赫数增加，流动分离区扩大，导致整机阻力增加，严重影响了高压捕获翼构型的气动性能。该现象成为宽速域下高压捕获翼构型设计中亟待解决的问题。在高超声速来流条件下，整机的升阻比是衡量高压捕获翼构型气动性能的关键指标。现有研究主要通过优化捕获翼外形来提升升力，进而提高整机的升阻比。然而，这些研究往往采用简化的圆锥或其组合体作为机身，并未考虑机体外形设计对整机升阻比的影响。因此，通过改变机体外形降低整机阻力，为提高高压捕获翼构型在设计工况下的气动性能提供了新的研究方向。针对上述问题，本文对高压捕获翼单翼原理构型展开数值模拟研究。主要的工作内容及结论如下：

首先，针对亚声速流场中机体与捕获翼间的流动分离现象，采用钝化方法以优化机体连接拐点处的设计。通过对亚声速、高超声速及其他速域下基准构型和钝化构型的流场结构和气动性能进行分析对比，揭示了机体拐角钝化对高压捕获翼构型气动特性的影响规律。具体结果如下：亚声速来流条件下，机体拐角钝化能有效地减弱甚至消除机体与捕获翼间的流动分离；进而降低整机的阻力系数，最大降幅可达69%。高超声速来流条件下，钝化半径的增加导致机体拐角膨胀波位置前移，但整体升阻比保持相对稳定。在宽速域范围内，机体拐角钝化可以改善高压捕获翼构型的流场结构，并显著降低整机的阻力系数。

其次，为进一步改善高超声速来流条件下高压捕获翼构型的气动性能，研究不同机身前体型线设计，包括圆锥、3/4幂曲线和卡门线，对流场结构、气动力、热参数的影响。通过对比分析，总结了型线变化对机体的减阻效果及整机气动性能的影响。具体结果如下：高超声速来流条件下，对于给定全长和底面半径的旋成体机体，当机体型线采用卡门线时，捕获翼的升力系数最大；当机体型线为3/4幂曲线时，机体阻力系数最小，且捕获翼下表面热流分布更为均匀，最大热流值显著降低。来流马赫数为8时，相较于采用简单的圆锥机身，机体型线采用卡门线的构型，整机的升阻比增加14.6%；而机体型线为3/4幂曲线时，整机的阻力系数下降10.2%，升阻比增大8.4%，捕获翼下表面斯坦顿数最大值减小29.9%。

上述工作为后续高压捕获翼构型机体外形设计奠定了理论基础。

Hypersonic flight has become a worldwide research hotspot because of its capability of long-distance cruising and rapid transportation. Several hypersonic aircraft concepts have been proposed in numerous countries in recent years. The current hypersonic aircraft configurations mainly include the blended wing body, the wing-body, the lifting body, and the waverider. The main features of the aforementioned aircrafts are to provide lift by compressing the incoming flow, while and the upper surface of aircraft is bulged for providing volume of loading. However, based on the above design ideas, there is a strong contradiction between the lift-to-drag ratio and volume in hypersonic conditions. The aircraft tends to be flat in order to obtain higher lift-to-drag ratio, resulting in limited loading capacity. Under beneficial aerodynamic interference, the innovative high-pressure capturing wing (HCW) configuration exhibits remarkable aerodynamic performances while ensuring a large volume at hypersonic speeds. At the same time, the additional lifting surface (high-pressure capturing wing, HCW) may significantly improve the lift at subsonic speeds, which makes the configuration a promising concept for wide-speed range vehicle design.

Compared with the traditional aerodynamic configurations, the most significant feature of HCW is that it produces complex aerodynamic coupling effects between the aircraft fuselage and HCW. Recent research has shown that compared to the single fuselage, the HCW can generate flow separations on the upper surface of the fuselage in lower subsonic flow conditions. The flow separation zone grows with the increase of Mach numbers, which considerably deteriorates aerodynamic performances of the vehicle. In hypersonic flows, lift is the primary consideration when designing a fuselage shape, and the cone is typically chosen. Therefore, it is important to keep the aerodynamic performance of the HCW configuration largely unchanged, while changing the fuselage shape to reduce the drag. Numerical investigations are conducted on the principle single-wing HCW configuration. The main work and conclusions are as follows :

Firstly, focusing on how to effectively eliminate the flow separation in subsonic incoming flow conditions, the influence of the bluntness at fuselage corner on the flow field structure is studied. Additionally, in hypersonic conditions, the expansion wave at fuselage corner might move forward due to the effect of bluntness. Therefore, the influence of the fuselage corner bluntness is also studied in the design condition. The results show that under subsonic conditions, with the increase of blunt radius at fuselage corner, the flow separations on the upper surface of the fuselage can be effectively restrained; the drag coefficient of the vehicle decreases significantly by 69% when the blunt radius is 600mm. Under hypersonic conditions, the expansion wave at the fuselage corner moves forward with the radius increasing, leading to a slight drop in the lift of HCW. The bluntness at the fuselage corner also results in a reduction in the drag of the fuselage. The lift-to-drag ratio remains virtually unchanged. On this basis, the range of incoming Mach numbers is broadened, it can be found that the fuselage corner bluntness can improve the flow field structure and significantly reduce the drag coefficient of the whole configuration in the wide speed range.

Subsequently, the flow field structure, aerodynamic forces and Stanton numbers of the HCW configurations corresponding to the body shape of cone, 3/4 power law curve, and Karman ogive are calculated, and the influence of the change of the fuselage shape on the aerodynamic performance is studied. The results show that for a slender revolutionary body with a given length and radius, opting for a convex body shape will make the position of the reflected shock wave move forward, in which case the area of the high-pressure zone on the lower surface of the HCW increases. For a convex body shape, expansion waves appear on the rear part of the fuselage owing to the decrease of the slope of the wall, resulting in a decrease of the pressure coefficient of the rear part of the fuselage and the lower surface of the HCW. The area of high pressure zone on the lower surface of the HCW of the Karman ogive configuration is the largest, so the lift coefficient is the largest. While the 3/4 power law body can effectively reduce the drag coefficient of the HCW configuration. Therefore, the lift-to-drag ratio of these two configurations are improved compared with the conical HCW configuration. Additionally, the Stanton number on the lower surface of the HCW of the 3/4 power law curve configuration is more uniform. In the condition of Mach number 8, compared with the conical HCW configuration, the lift-drag ratio of the Karman ogive configuration is increased by 14.6%; and the 3/4 power law curve configuration exhibits a 10.2% reduction in drag coefficient and a 29.9% decrease in maximum Stanton number on the lower surface of the HCW.

The obtained results can provide a reference for the design and optimization of the fuselage of the HCW configuration.