رسالة جامعية
Experimental Investigation of Space Debris Separation in Cold Hypersonic Flow Using a Free-flight Measurement Technique
| العنوان: | Experimental Investigation of Space Debris Separation in Cold Hypersonic Flow Using a Free-flight Measurement Technique |
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| المؤلفون: | Kovács, Dániel Gábor |
| المساهمون: | Dimitriadis, Grigorios, Chazot, Olivier |
| بيانات النشر: | ULiège - University of Liège [BE], 2024. VKI - Von Karman Institute for Fluid Dynamics, 2024. |
| سنة النشر: | 2024 |
| مصطلحات موضوعية: | space debris, aerodynamic separation, hypersonic, free-flight testing, VKI Longshot, fragmentation, re-entry, Engineering, computing & technology, Aerospace & aeronautics engineering, Ingénierie, informatique & technologie, Ingénierie aérospatiale |
| الوصف: | The aerodynamic forces and aerothermal loads experienced by spacecraft components during a fragmenting re-entry likely influence their trajectories, demisability, and, as a consequence, the resulting ground casualty probability. Due to the complexity of this phenomenon, Design for Demise tools often simplify the dispersion of the fragments and the interactions between the components, considering their trajectories as independent (i.e. neglecting any mutual interaction) as soon as a structural limit triggers the fragmentation event. Studying the interaction of proximal bodies and clusters is required to develop improved separation models that can advance demisability predictions.The present doctoral thesis experimentally examines aerodynamic interactions between separating space debris objects in cold hypersonic flow conditions. The investigations are executed in the VKI Longshot wind tunnel at Mach 12 and Mach 14 flow conditions. The newly manufactured Mach 14 nozzle is commissioned via a flow characterization campaign, revealing crucial parameters for the design of free-flight experiments, which are, hence, used throughout the work.In free-flight testing methodology, the test model is exposed to the flow without structural constraints; hence, it performs an unrestricted flight driven by its aerodynamic properties, the freestream conditions, and gravity. The aerodynamic forces and moments are then derived from the model's motion in the freestream. In short-duration facilities, the capabilities of free-flight testing techniques proved superior to balance measurements since they allow unperturbed flowfields in the close vicinity of the test articles, and optical-based methods permit the analysis of multiple models simultaneously. A state-of-the-art free-flight testing technique has been developed in the frame of this doctoral work. The methodology employs two high-speed cameras to record via the Schlieren system of the wind tunnel a side view and via a backlighting setup a top view perspective of the experiments. A contour-matching-based algorithm is developed to identify the position and attitude of one to multiple test articles at the same time, which may even present significant overlaps. Six degrees-of-freedom flight trajectories are derived from such analyses, allowing the computation of the aerodynamic forces that drove the motion.The thesis presents a macroscopic to microscopic analysis of space debris separations via particular experimental campaigns investigating the behavior of fragment clusters, two separating proximal bodies, and the interaction of a typical debris object with a two-dimensional curved shock wave. Experiments with clusters and two-body tandem configurations of spherical and cuboid fragments confirm a high degree of dependency on the shape of the objects. Testing with cubes presented significantly (~40%) higher mean separation velocities, larger extrema, and more substantial test-to-test variability. The interference of an annular ring with the two-dimensional shock wave was a microscopic-scale study, coupling the flow visualization, the flight trajectory, and the measured aerodynamic coefficients. During the most interesting test, a significant flow-normal velocity is induced even at the early stage of the interaction, which could promote a shock wave surfing configuration and contribute to object dispersal in a real fragmentation scenario.Overall, the experimental observations conducted in the framework of this thesis suggest a strong influence on the bodies’ initial arrangement and the individual orientations, which are also responsible for the induced lift, that must have an essential contribution to the spread. |
| نوع الوثيقة: | doctoral thesis http://purl.org/coar/resource_type/c_db06 doctoralThesis |
| اللغة: | English |
| ردمك: | 978-2-87516-211-3 2-87516-211-X |
| URL الوصول: | https://orbi.uliege.be/handle/2268/320150 |
| حقوق: | restricted access http://purl.org/coar/access_right/c_16ec info:eu-repo/semantics/restrictedAccess |
| رقم الأكسشن: | edsorb.320150 |
| قاعدة البيانات: | ORBi |
| ردمك: | 9782875162113 287516211X |
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