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Herrmann S.,University of Bremen | Goklu E.,University of Bremen | Muntinga H.,University of Bremen | Resch A.,University of Bremen | And 3 more authors.
Microgravity Science and Technology | Year: 2010

The realization of a Bose Einstein condensate in the Bremen drop tower as achieved by the QUANTUS collaboration in 2007 has added a new field to microgravity research: the study of freely evolving degenerate quantum gases at largely extended evolution times. Here we give an outlook on some experiments that could be done with such ultra-cold quantum gases in this unique laboratory and on other microgravity platforms to study fundamental physics questions. In particular we consider experiments that could employ the increased precision of matter wave interferometers in microgravity to search for low-energy phenomena of quantum gravity. © 2010 Springer Science+Business Media B.V.


Bauder U.,Institute For Raumfahrtsysteme | Majid A.,Institute For Raumfahrtsysteme | Fertig M.,German Aerospace Center | Auweter-Kurtz M.,Steinbeis Transferzentrum Plasma und Raumfahrttechnologie
10th AIAA/ASME Joint Thermophysics and Heat Transfer Conference | Year: 2010

The Finite-Volume Navier-Stokes code SINA was originally developed for the numerical simulation of re-entry problems and plasma wind tunnels. Therefore, the chemistry was fixed to Parks model for N2O2. In order to expand the operation purpose to hydrogen driven electric plasma sources or Martian atmosphere entry simulation for example, the chemistry part of the loosely coupled scheme is rebuilt more flexible using external files for the definition of the reaction scheme. A reaction scheme for hydrogen is implemented and the results are shown. The chemistry is solved using a Newton-method with numerical derivation and an Euler timestep for stability. © 2010 by the authors.


Lohle S.,University of Stuttgart | Lohle S.,Institute For Raumfahrtsysteme | Steinbeck A.,University of Stuttgart | Steinbeck A.,Institute For Raumfahrtsysteme | And 2 more authors.
Journal of Thermophysics and Heat Transfer | Year: 2016

The results of local measurements of the mass-specific enthalpy in a high-enthalpy oxygen plasma flow are presented. The sensor measures enthalpy based on stagnation point heat flux measurements and its reduction by mass addition into the boundary layer. The efficiency of this boundary-layer cooling depends on the freestream enthalpy. Thus, an analysis of this heat flux reduction is a measure for enthalpy. The enthalpy probe is described and theoretically analyzed, and measured data are compared to locally resolved enthalpy measurements from optical diagnostic measurements. For the pure oxygen plasma flow, a simplified theoretical model neglecting chemical reactions and diffusion fits comparably well to the measurements based on optical diagnostics. The mass-specific enthalpy at the corresponding plasma condition applying optical diagnostics is h = 27.47 MJ/kg, and the probe measures h = 27.64 MJ/kg.


Lohle S.,University of Stuttgart | Bohrk H.,German Aerospace Center | Fuchs U.,Institute For Raumfahrtsysteme | Kraetzig B.,Institute For Raumfahrtsysteme | Weih H.,German Aerospace Center
18th AIAA/3AF International Space Planes and Hypersonic Systems and Technologies Conference 2012 | Year: 2012

The German Aerospace Center (DLR) has developed a ceramic fin experiment (FinEx) for the HIFiRE-5 flight in order to test the performance of new structures with sharp leading edges during flight. The analysis of the thermal performance of the fin has been foreseen to be conducted by in-depth mounted thermocouples protocolling temperatures during flight. In a cooperative attempt between DLR and the Institut für Raumfahrtsysteme (IRS) of the University of Stuttgart, the thermal behavior is studied. In this paper, an approach is presented to determine the heat flux distribution onto the surface of the three-dimensional geometry of the fin. Using the Non-Integer System Identification (NISI) method, heat flux onto different surface elements is derived from only three thermocouples mounted inside the fin. Moreover, to increase accuracy, an area-weighted inverse method is used. The principal proof of concept is given based on a finite element thermal analysis of a cube. Measurements with a backup fin are used to show the approach experimentally in a plasma wind tunnel. Finally, the in-flight data has been evaluated and heat flux onto the fins during flight is presented. It can be concluded that the method is strongly dependent on surface discretization. However, the qualitative distribution is accurately determined. This approach allows to improve heat flux measurements for sparsely equipped flight hardware. © 2012 by the authors. Published by the American Institute of Aeronautics and Astronautics, Inc.


Lohle S.,University of Stuttgart | Lohle S.,Institute For Raumfahrtsysteme | Fuchs U.,University of Stuttgart | Fuchs U.,Institute For Raumfahrtsysteme
Journal of Thermophysics and Heat Transfer | Year: 2011

A method is presented that allows the determination of the net heat flux to surfaces from in-depth thermocouple measurements, which holds also for actively cooled environments such as transpiration cooled surfaces using porous materials. A heat flux determination from in-depth thermocouples is of particular interest in high-temperature and chemically reactive environments such as combustion or fusion chambers and thermal protection systems. However, the classical analytical approaches are very difficult to apply in those environments. The main problems are the unknown mounting of the thermocouple and the cooling gas mass flow that leads to an increased internal heat transfer. In the paper the noninteger system identification method is applied to a transpiration cooled system. A thermocouple mounted in the porous structure measures temperature rise due to laser-induced radiative surface heat flux. The identification procedure shows that knowing cooling gas mass flow through the porous structure is sufficient to determine heat flux from the temperature data with an accuracy<16%. It is shown that the heat transfer at the surface does not disturb the method. This approach is useful for many applications of actively cooled structures, for example turbine blade measurements, combustion chamber diagnostic, or even fusion chamber wall measurements, where very high heat fluxes can only be withstood by actively cooled structures. An outlook is given that shows that this approach can be used also to determine the internal heat transfer. Copyright © 2010 by Jason Meyers. Published by the American Institute of Aeronautics and Astronautics, Inc.


Eichhorn C.,University of Stuttgart | Eichhorn C.,Institute For Raumfahrtsysteme | Lohle S.,University of Stuttgart | Lohle S.,Institute For Raumfahrtsysteme | And 6 more authors.
Journal of Propulsion and Power | Year: 2012

Two-photon absorption laser-induced fluorescence (TALIF) measurements of relative ground state densities of neutral xenon on the plume axis of the radio-frequency ion thruster RIT-10 are reported. A TALIF scheme involving excitation of the 6p[1/2] 0 was applied. TALIF signals have been analyzed both in the cold gas flow and during thruster operation. Results show the principle feasibility of the investigated TALIF scheme, which seems to be a useful extension to formerly applied TALIF transitions for diagnostics in a thin xenon plasma. Copyright © 2012 by C. Eichhorn, S. Löhle, S. Fasoulas, H. Leiter, S. Fritzsche, and M. Auweter-Kurtz. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.


Lohle S.,Institute For Raumfahrtsysteme | Fuchs U.,Institute For Raumfahrtsysteme | Digel P.,Institute For Raumfahrtsysteme | Hermann T.,Institute For Raumfahrtsysteme | Battaglia J.-L.,Institute Of Mecanique Et Dingenerie Of Bordaux
Inverse Problems in Science and Engineering | Year: 2014

The paper presents the application of the non-integer system identification (NISI) method with a focus on the analysis of the system's impulse response. The NISI method being first published in 2001 has been applied to very different inverse heat conduction problems. The results presented in this paper are new findings developed by considering the impulse response as the characteristic of the investigated system. This assumption allows a different view to the problems where the method so far has been restricted. Examples are shown for a system with variable thermophyiscal properties and a surface under transpiration cooling. © 2013 Taylor & Francis.


Lohle S.,Institute For Raumfahrtsysteme | Lein S.,Institute For Raumfahrtsysteme
Review of Scientific Instruments | Year: 2012

A revised scientific instrument to measure simultaneously kinetic temperatures of different atoms from their optical emission profile is reported. Emission lines are simultaneously detected using one single scanning Fabry-Perot-interferometer (FPI) for a combined spectroscopic setup to acquire different emission lines simultaneously. The setup consists in a commercial Czerny-Turner spectrometer configuration which is combined with a scanning Fabry-Perot interferometer. The fast image acquisition mode of an intensified charge coupled device camera allows the detection of a wavelength interval of interest continuously while acquiring the highly resolved line during the scan of the FPI ramp. Results using this new setup are presented for the simultaneous detection of atomic nitrogen and oxygen in a high enthalpy air plasma flow as used for atmospheric re-entry research and their respective kinetic temperatures derived from the measured line profiles. The paper presents the experimental setup, the calibration procedure, and an exemplary result. The determined temperatures are different, a finding that has been published so far as due to a drawback of the experimental setup of sequential measurements, and which has now to be investigated in more detail. © 2012 American Institute of Physics.


Lohle S.,Institute For Raumfahrtsysteme | Mezger A.,Kayser Threde GmbH | Fulge H.,Institute For Raumfahrtsysteme
Acta Astronautica | Year: 2013

The Hayabusa sample return capsule, which contained asteroid samples, re-entered the Earth's atmosphere on June 13, 2010. An ablative carbon-phenolic thermal protection system (TPS) was used to enable a safe return for the small capsule and the containing samples. Besides a research aircraft operated by NASA with a wide range of imaging and spectrographic cameras for remote sensing of the radiation of the Hayabusa capsule during its entry flight, observation from ground based stations has been realized. We participated in the ground based observation campaign with two instruments for spectroscopic and photometric measurements aiming to detect the surface temperature and the plasma radiation in front of the re-entering capsule. The system consists in an infrared camera and a wide range miniature fibre spectrometer. The paper presents the setup, the laboratory calibration procedure, and correction for transmission. The surface temperature of the capsule reached a peak of 3250 K when the capsule was at an altitude of 55.95 km. The thermographic camera measures independently slightly higher temperature at peak heating (3308 K). © 2012 Elsevier Ltd. All rights reserved.


PubMed | Institute For Raumfahrtsysteme
Type: Journal Article | Journal: The Review of scientific instruments | Year: 2012

A revised scientific instrument to measure simultaneously kinetic temperatures of different atoms from their optical emission profile is reported. Emission lines are simultaneously detected using one single scanning Fabry-Perot-interferometer (FPI) for a combined spectroscopic setup to acquire different emission lines simultaneously. The setup consists in a commercial Czerny-Turner spectrometer configuration which is combined with a scanning Fabry-Perot interferometer. The fast image acquisition mode of an intensified charge coupled device camera allows the detection of a wavelength interval of interest continuously while acquiring the highly resolved line during the scan of the FPI ramp. Results using this new setup are presented for the simultaneous detection of atomic nitrogen and oxygen in a high enthalpy air plasma flow as used for atmospheric re-entry research and their respective kinetic temperatures derived from the measured line profiles. The paper presents the experimental setup, the calibration procedure, and an exemplary result. The determined temperatures are different, a finding that has been published so far as due to a drawback of the experimental setup of sequential measurements, and which has now to be investigated in more detail.

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