Superposition Method for Force Estimations on Bodies in Supersonic and Hypersonic Flows

Abstract

Aerodynamic interactions of fragments of meteoroids and space debris during atmospheric entry influence the flight trajectories of the fragments and their strewn field on the Earth's surface as well as the meteoroids' airburst altitude and energy deposition rate in the atmosphere and thus the resulting ground damage. For the design of experiments in the Hypersonic Wind Tunnel H2K of DLR, German Aerospace Center in Cologne to investigate the interaction phenomena, a method is developed to estimate the forces on two interacting bodies in supersonic and hypersonic flows, which is more accurate than existing analytical and semi-analytical methods and more efficient than numerical simulations regarding the computational effort. It is based on the superposition of flowfields taken from a database of numerical simulations of a single body for a range of Mach numbers. Furthermore, three-dimensional computations of configurations of interacting bodies are carried out by NASA Ames Research Center. Results obtained with the superposition method are compared to the simulations by NASA and to results of computations that can be found in the literature. The results from the method show good agreement with the computations.Nomenclature a x 1 = streamwise acceleration of first sphere, m∕s 2

Aerodynamic Characteristics of the Retro Propulsion Landing Burn of Vertically Landing Launchers

“…It has an expansion area ratio of 5.5, resulting in an exit Mach number of 3.275 (for air), with a throat diameter of 5.45 mm, an exit diameter of 12.77 mm and an exit angle of 5.57°. The exit angle was chosen to be 5.57° to match the nozzle exit angle of the RETALT1 first stage engine which has a thrust optimized contour with an area expansion ratio of 15 (Marwege and Gülhan 2023). The choice of an expansion area ratio of 5.5 is shortly reasoned in the following.…”

“…The choice of an expansion area ratio of 5.5 is shortly reasoned in the following. In (Marwege and Gülhan 2023) the scaling approach for the expansion area ratio for the wind tunnel model nozzle for the hypersonic retro propulsion experiments of the RETALT1 vehicle in the H2K were explained in detail. It was designed to achieve the best possible similarity in the thrust coefficient and the ambient pressure ratio.…”

“…Finally, conclusions and an outlook close the paper. A complementary analysis of the unsteady aerodynamics of the hypersonic reentry burn can be found in (Marwege and Gülhan 2023).…”

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

“…Aerodynamics of simple-shaped bodies in high-speed flows is generating renewed interest in the field of atmospheric entry of meteoroids, space debris and separating components of launch systems. Especially in the past decade, the characterization of flowfields around single (Lee et al 2017;Seltner et al 2019;Rees et al 2020;Grossir et al 2020) and multiple bodies (Laurence et al 2012;Marwege et al 2018;Park and Park 2020;Register et al 2020) has gained importance with respect to fragmentation, demise and separation behaviors of these space objects undergoing atmospheric entry. The determination of their flight trajectories helps to predict the impact area of uncontrolled entering spacecrafts with the objective to protect persons and properties from harm.…”

Investigation of shock/shock interferences on the aerodynamics of a fragment in the wake of debris in a rarefied regime/at high altitude

“…Indeed, the sphere-sphere case is a canonical geometry that can nevertheless be expected to exhibit many of the important flow features of more realistic geometries. The trajectories of the interacting spheres were analysed experimentally in shock tube facilities using the free flight method (Laurence, Deiterding & Hornung 2007;Laurence, Parziale & Deiterding 2012;Park & Brown 2012;Fisher, Quinn & Smith 2018;Marwege et al 2018;Whalen & Laurence 2021). Only one experimental work concerns the interaction of cylinders in free flight conditions with a hypersonic shock tube (Leiser et al 2022).…”