Aerodynamic interactions of blunt bodies free-flying in hypersonic flow

IF 2.3 3区工程技术 Q2 ENGINEERING, MECHANICAL

Experiments in Fluids Pub Date : 2024-05-13 DOI:10.1007/s00348-024-03818-9

Patrick M. Seltner, Sebastian Willems, Ali Gülhan

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Abstract

This paper takes a new look at how the aerodynamic interactions of multiple bodies in high-speed flow affect their motion behaviors. The influence of the body shape and orientation on aerodynamic and stability behavior in the case of shock–shock and wake–shock interactions is the focus of this publication. Experiments were performed in the hypersonic wind tunnel H2K at the German Aerospace Center (DLR) in Cologne. Free-flight tests with tandem arrangements of spheres and cubes were performed with a synchronized dropping of both objects at various initial conditions of relative streamwise and vertical distance as well as pitch angle. A high-speed stereo-tracking captured the model motions during free-flight, and high-speed schlieren videography provided documentation of the flow topology. Based on the measured 6-degrees-of-freedom (6DoF) motion data, aerodynamic coefficients were determined. As a result, the final lateral velocity of trailing cubes is found to be many times greater than that of spheres regarding shock-wave surfing. For rotating cubes, the results showed that stable shock-wave surfing can become possible over an increasingly wide range of initial positions. This study has identified that the trailing drag coefficient of two axially aligned objects varies strongly with their relative streamwise distance. Furthermore, it was shown that the wake is a region of stability for downstream objects.

Graphical abstract

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钝体在高超音速气流中自由飞行的空气动力相互作用

本文以全新的视角探讨了高速气流中多个物体的气动相互作用如何影响其运动行为。在冲击-震荡和尾流-震荡相互作用的情况下，机体形状和方向对气动和稳定性行为的影响是本文的重点。实验在科隆德国航空航天中心（DLR）的高超音速风洞 H2K 中进行。在不同的相对流向和垂直距离以及俯仰角的初始条件下，两个物体同步下降，进行了球体和立方体串联排列的自由飞行试验。高速立体跟踪捕捉了模型在自由飞行过程中的运动轨迹，而高速裂片摄影则提供了流动拓扑结构的记录。根据测量到的 6 自由度（6DoF）运动数据，确定了空气动力系数。结果发现，就冲击波冲浪而言，拖曳立方体的最终横向速度是球体的数倍。对于旋转立方体，研究结果表明，稳定的冲击波冲浪可以在越来越宽的初始位置范围内实现。这项研究发现，两个轴向排列物体的尾流阻力系数随其相对流向距离的变化而变化很大。此外，研究还表明，尾流是下游物体的稳定区域。

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来源期刊

Experiments in Fluids 工程技术-工程：机械

CiteScore

5.10

自引率

12.50%

发文量

157

审稿时长

3.8 months

期刊介绍： Experiments in Fluids examines the advancement, extension, and improvement of new techniques of flow measurement. The journal also publishes contributions that employ existing experimental techniques to gain an understanding of the underlying flow physics in the areas of turbulence, aerodynamics, hydrodynamics, convective heat transfer, combustion, turbomachinery, multi-phase flows, and chemical, biological and geological flows. In addition, readers will find papers that report on investigations combining experimental and analytical/numerical approaches.