Aerodynamics of inclined cylindrical bodies free-flying in a hypersonic flowfield

Abstract

The influence of the flight attitude on aerodynamic coefficients and static stability of cylindrical bodies in hypersonic flows is of interest in understanding the re/entry of space debris, meteoroid fragments, launch-vehicle stages and other rotating objects. Experiments were therefore carried out in the hypersonic wind tunnel H2K at the German Aerospace Center (DLR) in Cologne. A free-flight technique was employed in H2K, which enables a continuous rotation of the cylinder without any sting interferences in a broad angular range from 0$$^{\circ }$$ ∘ to 90$$^{\circ }$$ ∘ . A high-speed stereo-tracking technique measured the model motion during free-flight and high-speed schlieren provided documentation of the flow topology. Aerodynamic coefficients were determined in careful post-processing, based on the measured 6-degrees-of-freedom (6DoF) motion data. Numerical simulations by NASA’s flow solvers Cart3D and US3D were performed for comparison purposes. As a result, the experimental and numerical data show a good agreement. The inclination of the cylinder strongly effects both the flowfield and aerodynamic loads. Experiments and simulations with concave cylinders showed marked difference in aerodynamic behavior due to the presence of a shock–shock interaction (SSI) near the middle of the model. Graphic abstract

Meteoroid rotation and quasi-periodic brightness variation of meteor light curves

“…1. Drag and lift coefficients as a function of the angle of attack for the cases of a rotating cube (upper panel) and a rotating cylinder (lower panel), as derived by Seltner et al (2019Seltner et al ( , 2021. The red curve in the middle of each panel shows, in arbitrary units, the varying cross sectional area.…”

“…However, these earlier studies tended to focus on the drag of cylindrical bodies in axial flows and crossflows at supersonic speed, while the issue of inclined right circular cylinders in hypersonic flows was neglected. Seltner et al (2021) addressed this gap by publishing the results of experimental and numerical investigations of pitched cylindrical bodies in hypersonic flow, ascertaining both the aerodynamic drag and lift force.…”

“…It has been recently proven by Seltner et al (2019Seltner et al ( , 2021) that the aerodynamic drag and lift coefficients of rotating cubes and cylindrical bodies in hypersonic flow have a significant dependence on the body orientation. Seltner et al (2019) calculate the aerodynamic coefficients of a rotating cube using the free-flight technique in a hypersonic flowfield.…”

“…The peak of the lift coefficient for a rotating cube is thus about 12% of the maximum drag coefficient. Seltner et al (2021) also calculated the drag and lift coefficients for a rotat-ing cylinder in hypersonic flow, obtaining a detailed dependence of C D and C L on the angle of attack, also shown in Fig. 1.…”

Editorial: topical collection on hypersonic flight

“…The contributions of Gülhan et al (2021), Running and Juliano (2021), and Threadgill and Little (2022) concentrate on the important problems of shock-wave/boundary-layer interactions and shock-shock interactions (SSI), while Cardona et al (2021) extend the study of SSI to the rarefied regime. Investigations of the free-flight aerodynamics of single (Seltner et al 2021) and multiple (Whalen and Laurence 2021) bodies, relevant to space debris reentry and meteoroid fragmentation in the atmosphere, are also included in the collection; free-flight experiments on a large scramjet model are documented in Tanno and Tanno (2021).…”