Development of hypersonic combined test facility and study of force measurement including aerothermodynamic phenomena

Abstract

in comparison to test results that did not take wall temperature into account, the drag coefficient increased by 15.1 % for the STS303 model ((Tw/T0: 0.97), 7.49 % for the AL6061 model ((Tw/T0: 0.58), and 9.83 % for the copper model ((Tw/T0: 0.48). After the preheating experiment, the cooled model and the machining surface roughness comparison revealed a drop in the drag coefficient for copper (-4.49 %), AL6061 (-1.10 %), and STS303 (-5.65 %). This results from the heated surface’s enhanced roughness after preheating. Based on surface observations using scanning electron microscopy, the drag coefficient as a function of surface roughness was found to be AL6061 > copper > STS303 by comparing the cooled models after preheating. This was in the reverse order of roughness.

This extensive study describes the design and implementation of a hypersonic combined test facility for aerothermodynamic ground testing, combining an arc-jet tunnel, a shock tunnel, and a model transport system into a single test section. The facility has a model transport system and a small-scale Huelstype arc-jet tunnel for preheating test model surfaces so that a smooth transition to the shock tunnel is possible. Every component underwent performance validation tests, with a focus on maintaining control over the wall-to-total temperature ratio by preheating the model surface through aerodynamic heating in the arc-jet tunnel and conducting shock tunnel testing continuously. Development of Hypersonic Combined Test Facility - K4: By enabling simultaneous testing in both tunnels, the integrated setup optimizes the conditions for the experiments. With a 10 mm diameter flat-faced model operating in nitrogen, the arc-jet tunnel produces a high-enthalpy flow of 1.99±0.03 MW/m2, and in air conditions, 1.97±0.01 MW/m2. The shock tunnel simulates a 24 km pressure altitude Mach 5 flight. A combined test at 477 K was conducted after preheating the test model, a conical AL6061 structure, to a temperature of 603 K. Extensive analyses of the experimental outcomes and performance highlight this hypersonic test facility’s potential. The developed facility has great potential for use in the analysis and research of hypersonic flow. With its potential to greatly expand our knowledge of aerothermodynamic phenomena, it will help us design and operate hypersonic vehicles more effectively. The cone model was subjected to detailed assessments using a combined test, which revealed distinct shape changes caused by the ablation effect. The cone became a blunted double cone shape, and there were changes to the shock patterns: attached shock to detached bow shock transitions, separation shock, reattachment shock, and shock-shock interactions. These combined test observations offer crucial information about the dynamic changes the model goes through when aerothermodynamic forces are applied. Initial studies of the hemisphere model demonstrated surface roughness changes with preheating session. Although the results of the flow visualization were not very noticeable, the differences in surface roughness that were noticed offer a fascinating direction for future research. It becomes clear that specific methods must be developed in order to study and examine how these aerothermodynamic phenomena affect aerodynamic forces. The pre-combined test analysis provides a basis for improving methods and comprehending the intricate relationships between aerodynamic forces and surface conditions. Conditions specifically designed for shock tubes called tailored condtion were used to prolong the steady state for the force measurement test. This improvement entails modifying a few key shock tunnel operating parameters. A gas mixture consisting of 95.5 % helium and 4.5 % nitrogen is used to optimize the driver tube’s filling state. With this adjustment, the shock tunnel’s overall effectiveness will be improved, which will help force measurement tests maintain steady-state conditions longer. Pitot pressure had a substantially longer steady time, ranging from 520 µs to 2.8 ms. The purpose of this intentional modification was to offer a longer duration of steady and uniform Pitot pressure circumstances, guaranteeing a more resilient and trustworthy setting for force measurement experiments. These customized shock tunnel conditions show how carefully the experimental configuration has been refined, highlighting the dedication to attaining long-lived steady states necessary for precise force measurements inside the hypersonic combined test facility. Development of Force Measurement Technique for Preheated Model: This work presents a new method for measuring forces that is being used in the hypersonic combined test facility to examine how forces are affected by aerothermodynamic phenomena, specifically aerodynamic heating. A model transport system that has been preheated is part of the technique, which allows for quasi-free-body axial motion during force measurement tests. Comparative analyses show that the drag coefficient for preheated models increases by 10 %. This study provides a realistic simulation of hypersonic flight by analyzing the effects of surface temperature and ablation-induced shape changes on drag coefficients under different conditions. It is expected that this recently developed force measurement method will be essential in forecasting the behavior and flight path of hypersonic flight objects, improving the overall performance, efficiency, and design of hypersonic vehicles. Investigation of Effects of Aerothermodynamic Phenomena on Drag Force: This study examined the effects of surface roughness, wall temperature, ablation-induced shape change, and machined surface roughness. Additionally, it examined how surface roughness and wall temperature interact to affect the drag coefficient and examined each independently of the combined effects. The drag coefficient of the conical test model made of AL6061 material increased by 2.67 % as a result of the ablation-induced shape change. The drag coefficient for the hemispherical test models of different materials changed significantly as a result of the wall temperature effect