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Viewing 1 to 18 of 18
1992-07-01
Technical Paper
921202
Albert Braig, Thomas Meisel, Walter Schwarzott
Abstract Electroemissive (ESTHER) devices are thin sheets - similar to solar cells - whose infrared emissivity can be varied reversibly by electrical charging. Bonded to the external surfaces of spacecraft radiators they can be used for the active control of the Irradiated heat by consuming negligible electrical energy. The window to a revolutionary new thermal control design technology for spacecraft may be opened.
1992-07-01
Technical Paper
921294
N. J. Stock, G. Singh, R. Bisanz, F. Zilly, A. Lebru
This paper discusses the capabilities of the ABLAT software which has been developed by ERC and Dornier for the European Space Agency. The software provides an ablation modelling capability for the ESATAN thermal analyser and consists of two sections: i. A stand-alone preprocessor allowing specification of the ablation model. This has both an X11/OSF Motif and a command line interface. ii. An integrated solver capability within the ESATAN system, allowing transient analysis of an ablating surface in conjunction with a standard thermal model. After a brief overview of the major aims of the development, the software is discussed from two main points of view, the user interface facilities (how the user defines the model to the system), and the calculation facilities (what can be calculated, and how are these calculations performed).
1994-06-01
Technical Paper
941414
L. Eckert, Ch. Pütz, R. Treichel
1. ABSTRACT On behalf of the German Space Agency, DARA, the Spacelab facility NIZEMI (Slow Rotating Centrifuge Microscope) was developed for IML-2 mission in July 1994. The facility permits the investigation of samples under various levels of acceleration. Primary utilization of the facility during the IML-2 mission is for the investigation of samples in the field of gravitational biology. For observation purposes two optical units, a microscope and a macroscope, and the infrastructure for thermal control of the samples has been installed on a centrifuge turntable. The acceleration can be adjusted at levels between 10-3 g and 1.5 g. The rotating centrifuge itself and several moveable items like fans and stages, which are attached on the centrifuge turntable, may affect the microgravity environment of Spacelab. The equipment accommodated on the centrifuge turntable does not allow a design for a uniform mass distribution.
1994-06-01
Technical Paper
941582
Ulrich Trabandt, Wilfried Becker, Alain Pradier
On three different materials, C/C, C/SiC and SiC/SiC, bending tests under thermo-mechanical cycles have been performed, in accordance with the thermal load conditions of hypersonic launch and re-entry. The samples have been manufactured with oxidation protective coatings in order to investigate also the effect of oxidizing environment. In order to assess the influence of initial defects the test samples have been prepared with different drilled holes. Thereby, high sensitivity with respect to the initial defect size can be stated. Eventually, as an actual structural component a C/SiC heat shingle has been manufactured and is going to be validated.
1994-06-01
Technical Paper
941583
G. Reich, U. Trabandt, K. Keller
Actively cooled and re-radiative leading edges were investigated as typical thermal protection elements for thermally high loaded areas of advanced launchers. A performance trade-off led to the selection of a C/SiC thermostructural concept. Mechanical and thermal analyses demonstrated the adequacy of the selected design. Manufacturing leading edge demonstrators with a small nose radius, different thicknesses of the outer skin and the integration of stringers was realised with good surface smoothness and contour accuracy. Thermal cycle tests with temperatures up to 1000°C in an oxidising environment were performed without any visible damage.
1991-07-01
Technical Paper
911481
C. Pietsch, J. Hauser
This paper describes the development, manufacturing and testing of an advanced heat pipe profile possessing separated arteries and small radial grooves for condensate transportation. The objective of the development was to design a heat pipe with improved heat transport capability limited by an outer cross-section of 15 mm square. The concept of the new heat pipe is based on an aluminium extrusion profile with rectangular outer shape. The central vapour core of 9.2 mm diameter is connected via small connection slots with four individual liquid channels located in the corner areas of the profile. So the liquid flow in the four channels is decoupled from vapour flow, both streaming in opposite directions. Decreasing of the pressure drop in the liquid channels and decreasing the entrainment of liquid flow to the vapour flow resulted in improved heat transport capability.
1994-06-01
Technical Paper
941352
P. Rosenthal, W. Keil, R. Bisanz, J. Sorensen
ESABASE/SUNLIGHT is a software tool to calculate illumination, effective illumination, exposure time, incident electromagnetic power, absorbed electromagnetic energy for spacecraft surfaces during planet orbiting missions considering sun and planet irradiation, effects of eclipse and self-shading, multireflections, transmission, pointing and (variable) geometry. Calculation applies a fast Monte Carlo raytracing algorithm and is based on wavelength dependent spectra and material properties. ESABASE/SUNLIGHT is fully integrated in the CAE-frame ESABASE which offers a powerful geometry specification language, orbit generator, pointing facility and advanced libraries as well as gateway, pre-, postprocessing and display tools with the benefits of standardisation and exchange to other analysis tools.
1993-07-01
Technical Paper
932133
Jens Eickhoff, Reinhold Bisanz, Friedbert Zilly, Wolfgang Keil
As a consequence of the continuously increasing complexity of design, development and qualification of modern spacecraft subsystems, computer aided tools become increasingly important for solving the various engineering tasks in these fields. In the framework of development tasks for satellites and space stations, e.g. ERS-I/II, ROSAT, CLUSTER, SOHO, COLUMBUS-ECLSS, and HERMES a software environment has been developed at Dornier GmbH in recent years, which allows thermal analysis, thermal control and space environment control for system simulation as well as for detained component level simulation, monitoring and testdata evaluation. COSITHERM is a modular software package for the prediction of thermal radiation effects. SIMTAS can be used for detailed analysis of single system components as well as for the prediction of system response of arbitrarily connect components.
1993-07-01
Technical Paper
932134
Andreas Natusch, Markus Huchler
Manned space laboratories like the US Space Station Freedom or the european COLUMBUS APM are equipped with so-called racks for subsystem and payload accommodation. An important resource is air for cooling the unit internal heat sources, the avionics air. Each unit inside the rack must be supplied with sufficient amount of air to cool down the unit to the allowable maximum temperature. In the course of the COLUMBUS ECLSS project, a thermohydraulic mathematical model (THMM) of a representative COLUMBUS rack was developed to analyse and optimise the distribution of avionics air inside this rack. A sensitivity and accuracy study was performed to determine the accuracy range of the calculated avionics air flow rate distribution to the units. These calculations were then compared to measurement results gained in a rack airflow distribution test, which was performed with an equipped COLUMBUS subsystem rack to show the pressure distribution inside the rack.
1990-07-01
Technical Paper
901289
Wolfram Knorr, Helmut Funke, Helmut Preiss, Gijsbert Tan
In support of the Columbus ECLSS, a technology development program has been performed on four items: Regenerative CO2 removal Trace Gas Contamination Control Trace Gas Contamination Monitoring Low Noise Variable Speed Fan This paper describes the contents and results of the concluding Subsystem Level Tests and consecutive programme extensions which concentrated on: performance of the Contamination Monitoring Unit noise generation of the Variable Speed Fan lifetime tests of the CO2 removal solid amine closed water loop operation of a solid amine CO2 removal unit
1992-07-01
Technical Paper
921245
Karl Honnen, Markus Huchler
The pressurized modules use water and air coolant circuits to remove the dissipated heat from the sources and to transport it to the heat sink. The advantage of the water loops is to provide a high heat removal capability at low power consumption well suited for high specific heat loads i.e. assemblies with high dissipation and small volume. Air coolant circuits offer a higher flexibility to account for different shapes of the equipments and for changes in the configuration of the loop. Thus they are better suited for assemblies with lower dissipation and do not impose as much design restrictions on assemblies as water loops. But they have a higher specific power demand compared to water loops. In the Columbus pressurized modules avionics air loops and cabin air loops are installed. Both of them belong to the Environmental and Life Support Subsystem (ECLSS).
1994-06-01
Technical Paper
941306
Karl Honnen, Markus Huchler
The redesign of the international Space Station Freedom (SSF) and funding constraints in the ESA member states caused a redirection of the development effort for the Attached Pressurised Module (APM). For the ECLSS the most important changes are the reduction in length of the module in order to make it compatible with the ARIANE V capabilities and the more severe cost constraints. As a result new concepts for the cabin loop were investigated leading to a decrease in cabin loop power consumption, mass and volume and a reduced development effort due to a lower number of items. In the previous concept a module internal loop with a flow rate of 864m3/hr and an Intermodule Ventilation (IMV) flow rate for air revitalisation to the station with 240m3/hr were installed. The revised boundary conditions with a reduced overall massflow rate of 540m3/hr allows the combination of the cabin loop and the IMV with limited impact on the total power consumption.
1993-07-01
Technical Paper
932273
H. Funke, W. Jehle, A. Kreis, H. Preiβ, G. Tan
Europe is now implementing the COLUMBUS APM programme. The more ambitious planning of an European Free Flyer and Lunar mission are under orientation. Timewise, this gives some relief from the challenges for the Environmental Control and Life Support System (ECLSS). However, some of these challenging new technologies have already been subject of development programmes in the past, others which will be reported in this paper are currently under investigation. To regain the oxygen from the metabolic process a physicochemical system is under development. The selected chain is the CO2 concentration with a solid amine resin, the CO2 reduction via Sabatier reaction and the oxygen recovery by water electrolysis with fixed alkine electrolysis. To prove the concept a test bench has been built, starting in a first step with the set up of a CO2 Processing S/S (CO2 concentrator, CO2 management, CO2 reduction assembly).
1997-07-14
Technical Paper
972557
R. Forster, L. Eicher, J. Lucas, R. Müller, R. Perez Vara
The Mini Pressurized Logistic Module (MPLM) of the International Space Station (ISSA) is foreseen for the transport of service equipment, experiment racks and service racks to the station. For the orbital operational phase it needs an Environmental Control and Life Support System (ECLSS) to make it commissionable for the astronauts. Because of its short mission time and the usage as a transport vehicle it has no completely autonomous ECLSS functionality. The Temperature and Humidity Control (THC) is supported by the Space Station via an Inter Module Ventilation Interface (IMV l/F). The MPLM ECLS has the requirement to suck revitalized air through the IMV l/F and mix it up with the recirculated air in order to provide a comfortable atmosphere in the MPLM habitable area. The fulfillment of the hydraulic and thermal requirements is verified by test and analysis. With this paper we provide the hydraulic analysis performed with ECOSIM, an ESA approved software tool.
1985-10-01
Technical Paper
851766
C. A. Barényi, G. Benatti
The ALPHA JET Training System as a single aircraft concept consists of the training management system and Media for the following academics simulators aircraft It meets or exceeds all requirements for timely replacement of obsolete training system components effective and efficient management in the training of individual pilots optimum employment of all components of the training system. It significantly lowers pilot training costs and personnel support requirements through the use of computer assisted instruction and procedure devices the use of training management system a modern high performance training aircraft and latest state of the art simulators.
1992-07-01
Technical Paper
921289
Markus Huchler, Karl Honnen
Potential fires in the COLUMBUS Attached Pressurized Module (APM) shall be extinguished by reducing the O2 concentration in the atmosphere below 15 %. For this purpose a CO2-distribution system is foreseen. It injects CO2 stored in a tank into the volume where fire is to be extinguished. Due to its dimensions the most critical of these volumes is the subfloor with the stand-off areas. To investigate the fire suppression process a detailed three dimensional computational fluid dynamic analysis (CFD-analysis) was performed. The transient CO2-distribution mechanisms, forced convection and diffusion, were analyzed to examine the feasibility of the foreseen system and to optimize it. In this paper the governing physical processes and their implementation in the mathematical model of the problem are described. The very complex inlet conditions - speed of sound, tiny nozzles - are examined in detail to investigate a proper method for implementation in the mathematical model.
1992-07-01
Technical Paper
921400
Reinhard Schaefer, Stephen Luck, Gerhard Hauser
This paper presents some of the important aspects of the development work carried out recently in the Hermes ECLSS (since Ref. 1). For various constituent hardware items of the ECLSS, the paper describes and explains the technical constraints which are at the origin of the development work, discusses the design concepts which have been identified and investigated to fulfill the constraints, and presents the technical solution which has been selected. For some hardware items (e.g. cabin fan, toilet assembly), for which the initial design selection has been supported by breadboard tests, the paper presents the rationale behind such tests and the major test results obtained. The consequences derived from the test experience for the further development work are explained.
1994-06-01
Technical Paper
941465
Albert Braig, Thomas Meisel, Walter Rothmund, Ruediger Braun
Electro emissive devices, called ESTHER, are thin sheets - similar to solar cells - whose infrared emissivity can be varied reversibely by electrical charging. Bonded to external surfaces of spacecraft radiators, they allow active control of the heat radiated to space while consuming negligible electrical energy. Applying this novel component for spacecraft thermal control, considerable cost savings in spacecraft development and operation can be achieved. Progress in the design and manufacturing process has been made since the first puplication in July '92 /1/ revealing an increased variability of emissivity and an increased duty cycle stability. The material selection process was facilitated by the exposure of material samples to the space environment during two spaceflight missions and the subsequent material analyses.
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