Thermal and Fluid Modeling of the CRYogenic Orbital TEstbed (CRYOTE) Ground Test Article (GTA)
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The purpose of this study was to anchor thermal and fluid system models to data acquired from a ground test article (GTA) for the CRYogenic Orbital TEstbed - CRYOTE. To accomplish this analysis, it was broken into four primary tasks. These included model development, pre-test predictions, testing support at Marshall Space Flight Center (MSFC} and post-test correlations. Information from MSFC facilitated the task of refining and correlating the initial models. The primary goal of the modeling/testing/correlating efforts was to characterize heat loads throughout the ground test article. Significant factors impacting the heat loads included radiative environments, multi-layer insulation (MLI) performance, tank fill levels, tank pressures, and even contact conductance coefficients. This paper demonstrates how analytical thermal/fluid networks were established, and it includes supporting rationale for specific thermal responses seen during testing.Keywords:
Testbed
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본 논문은 HAUSAT-2 위성의 구조-열모델(STM)에 대해 수행한 우주모사시험의 결과 및 이에 따른 열 모델링의 수정과 해석에 대한 연구 결과를 보여준다. 열 모델링의 보정은 시험 데이터와의 비교 분석 과정을 반복하여 이루어졌으며, 이러한 보정된 열 모델링을 통해 시험데이터와 근사한 결과를 재해석 시에 얻게 되었다. HAUSAT-2의 열진공 및 열평형 시험에서는 표면히터를 사용하여 태양광을 모사하였다. 본 열진공 및 열평형 시험을 통하여 소형 열진공 챔버 내에서 국내 최초로 초소형 위성 모델을 우주모사시험하기 위한 저비용이며 효율적인 열시험 방법을 제시하였고, 또한 이를 시험 결과를 통해 검증하였다. This study addresses space simulation test results and thermal modelling verification of HAUSAT-2 nanosatellite STM (Structural-Thermal Model). The thermal modelling of the HAUSAT-2 has been modified in accordance with test results. Thermal analysis results were repeatedly compared with test results for modified thermal modelling. It is verified that the analysis results for modified thermal modelling agree well with test results. Some surface heaters were implemented to simulate solar illumination for HAUSAT-2 Thermal Vacuum/Balance Test. A low-cost and effective thermal test methodology, which is applicable to ultra-small satellite system, was proposed and verified by test results in this study.
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Development of thermally protected load-carrying structures of reusable launch vehicles capable to withstand the environment and manoeuvre loads during re-entry needs ground test facilities simulating at least the thermal input and mechanical loads under ambient atmospheric conditions. By this means, the predicted structural behaviour can be confirmed. As a consequence, the DLR-Institute of Structural Mechanics developed the THERMEX test facilities and still improves the test procedures. Within the first part of the presentation the recent challenging test series on European contributions to the X-38 re-entry vehicle will be highlighted. Testing the rudder model surface temperatures up to 1175 °C have been achieved by enforcing infrared lamp radiation. A strongly curved panel, the so-called nose skirt, was heated by accommodation of the heater arrays to the geometry of the test article. Because the nose skirt panel was manufactured from C/SiC very small deformations were measured by high-resolution displacement transducers. Within the preceding FESTIP activities cryogenic tank wall panels with an outer high-temperature insulation were tested simultaneously by an outside heating up to 950 °C and an inside cryogenic cooling by liquid nitrogen. Within the second part new developments for forthcoming tests will be illustrated. Such as testing of structures with complicated shapes under combined hot and cryogenic temperature loading will be considered. The concept of modular assemblage of facility components will allow a variety of applications, e.g. ablation exclusively caused by heat irradiation and even brazing of stringers to a titanium panel by fast infrared heating. Another attempt of improvement will be the feasibility to study kinematics of hot structures such as flaps or rudders. Again, the hot gas test facility, part of the THERMEX assembly, will be used to simulate in addition to the thermal loading aerodynamic pressure and flow as well as acoustic excitation. Measurement and data recording will be refined by new amplifiers allowing also the use of type S thermo-couples. For temperature determination even the application of colour coating and infrared camera recording will be studied. The presentation will close with considerations on realisation of successful test procedures. The most important aspect is pre-testing on dummy structures to optimise thermal input and temperature distribution within the tested structure, to adapt the ranges of measurement, and to determine the control parameters of thermal and mechanical loading, especially in the case of kinematics.
Thermocouple
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Conventional multi-layer insulations exhibit excellent insulation performance but they are limited to the temperature range to which their components reflective foils and spacer materials are compatible. For high temperature applications, the internal multi-screen insulation IMI has been developed that utilizes unique ceramic material technology to produce reflective screens with high temperature stability. For analytical insulation sizing a parametric material model is developed that includes the main contributors for heat flow which are radiation and conduction. The adaptation of model-parameters based on effective steady-state thermal conductivity measurements performed at NASA Langley Research Center (LaRC) allows for extrapolation to arbitrary stack configurations and temperature ranges beyond the ones that were covered in the conductivity measurements. Experimental validation of the parametric material model was performed during the thermal qualification test of the X-38 Chin-panel, where test results and predictions showed a good agreement.
Internal heating
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The high-speed reentry capsule of lunar spacecraft will face a weak vacuum environment long-term on orbit, thus the difference of heat-transfer capability of the multi-layer insulation blankets under different vacuum degrees should be evaluated in thermal design. In this article, an one-dimensional method of mesurement with adiabatic boundary condition was constucted to test the heat tranfer performance of multi-layer insulation blankets with 5, 10, 15 and 20 under 0.001-10000 Pa. Based on the test data, equivalent thermal conductivities of different vacuum degrees were calculated. The proper equivalent thermal conductivity is selected in the entire spacecraft thermal analyses, and this method is proved to be correct through thermal balance test and on orbit temperature telemetry. This work achieves not only basic data for reentry capsule, but also important fundation of thermal design and thermal analyse with multi-layer insultaion blankets in different vacuum degree.
Thermal bridge
Orbit (dynamics)
Dynamic insulation
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Covers advancements in spacecraft and tactical and strategic missile systems, including subsystem design and application, mission design and analysis, materials and structures, developments in space sciences, space processing and manufacturing, space operations, and applications of space technologies to other fields.
Hypervelocity
Spacecraft design
Space Suit
Space environment
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In order to maintain the cryogenic environment of cryogenic wind tunnel in service, heat transfer of insulation structure is investigated in this work. Firstly, the design and material selection of insulation structure is conducted. Afterwards, theoretical calculation on heat transfer of insulation structure is carried out based on 1-D heat conduction model. Subsequently, the finite element model of insulation structure is established, on this basis, involving the actual work condition of cryogenic wind tunnel, heat transfer of the insulation structure is numerically calculated. Finally, the testing platform able to simulate the work environment of cryogenic wind tunnel is built and the temperature measurement experiments at the cryogenic condition and at the cryogenic pressure condition are carried out, respectively. The obtained results show that the designed insulation structure is in possession of great insulation characteristics to ensure the cryogenic environment of cryogenic wind tunnel. Additionally, the established testing platform can provide a testing method to investigate the heat transfer character of other materials or structures in cryogenic environment.
Cryogenics
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The definition phase of an in-space experiment in thermoacoustic convection (TAC) heat transfer phenomenon is completed and the results are presented and discussed in some detail. Background information, application and potential importance of TAC in heat transfer processes are discussed with particular focus on application in cryogenic fluid handling and storage in microgravity space environment. Also included are the discussion on TAC space experiment objectives, results of ground support experiments, hardware information, and technical specifications and drawings. The future plans and a schedule for the development of experiment hardware (Phase 1) and flight tests and post-flight analysis (Phase 3/4) are also presented. The specific experimental objectives are rapid heating of a compressible fluid and the measurement of the fluid temperature and pressure and the recording and analysis of the experimental data for the establishment of the importance of TAC heat transfer process. The ground experiments that were completed in support of the experiment definition included fluid temperature measurement by a modified shadowgraph method, surface temperature measurements by thermocouples, and fluid pressure measurements by strain-gage pressure transducers. These experiments verified the feasibility of the TAC in-space experiment, established the relevance and accuracy of the experimental results, and specified the nature of the analysis which will be carried out in the post-flight phase of the report.
Thermocouple
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Active and passive thermal controls for simulations of a space IR sensor system operating in cryogenic temperatures were designed, built, and tested from a component level to a system level. The test results from component tests and integrated system tests have compared very well with theoretical predictions, and thus verify component and integrated thermal math models. These verified models can be modified for use to predict flight systems thermal performance. Thermal vacuum simulations and demonstrations of a space IR system consisted of a target and background scene generator, telescope mirrors supported by a graphite-epoxy metering structure, and an IR sensor. These components are required to operate at cryogenic temperature levels. Each component has its unique thermal control needs. Descriptions are presented of thermal control systems for the test article from component design level to integrated system level along with discussions of component and integrated demonstration tests, and correlation of test data with thermal finite difference models.
Component (thermodynamics)
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Abstract : Although predictive thermal modeling on CubeSats has previously been accomplished, a method to validate these predictive models with terrestrial experiments is essential for developing confidence in the model. As a part of this effort, AFIT has acquired a new Solar Simulation Thermal Vacuum Chamber. This research analyzed the thermal environment to which a test article is exposed within the AFIT Solar Simulation Thermal Vacuum Chamber. A computational model of the thermal environment in the chamber was created and then validated using an experimental buildup approach through thermal balance testing of the empty chamber and an aluminum plate. First, the modeled surface temperatures of the thermal vacuum chamber interior walls were validated within Terror 4 deg C of steady-state experimental data. Next, the aluminum plate computational model was validated within Terror 1?C of steady-state experimental data. Through these results, this research provides the capability to validate spacecraft and payload computational thermal models within the thermal vacuum chamber environment by comparing computational predictions to experimental data for steady-state cases. Additionally, this research validated an upgrade to increase optical performance of the TVAC by bolting a copper plate coated with Aeroglaze? black paint to the top of the platen, ensured safe procedures are in place for solar simulation, and improved the temperature controller performance.
Vacuum chamber
Payload (computing)
Thermal grease
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A theoretical and experimental parametric study of the heat-transfer phenomena on a multistage passive cryogenic radiator is presented. This investigation was performed in the frame of a cooperative effort between Clemson University and the Federal University of Santa Catarina. Passive cryogenic radiator technology is under development at the Satellite Thermal Control Laboratory at the Federal University of Santa Catarina, where two experimental prototypes have been built and ground tested. The mathematical model, developed to predict the temperature distribution on the radiator stages, was used to study the sensitivity coefficients with respect to the design parameters. The design parameters considered are the radiator stage's surface emissivity, the multilayer insulation effective emissivity, the radiator support's global conductance, and the thermal load over the radiator stages. This sensitivity analysis showed that the thermal joint conductance between the stages and the support structure (aluminum-Teflon®) plays an important role in the temperature distribution of the radiator. An experimental study was conducted within the Mechanical Engineering Department of Clemson University to gather thermal conductance data for comparison with the theoretical results. The thermal conductance data were incorporated into an analytical model developed for the prediction of the transient temperature behavior of a multistage cryogenic radiator for spacecraft applications. The data were also compared with the recently developed model for the prediction of thermal conductance of polymer and metal joints. Ultimately, conclusions are presented about the importance of the thermal conductance between the polymer support structure and the passive cryogenic radiator stages in the temperature distribution of the radiator.
Radiator (engine cooling)
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