Tobias Sander

Tobias Sander
Universität der Bundeswehr München · Fakultät für Luft- und Raumfahrttechnik

Prof. Dr.-Ing. habil.

About

41
Publications
1,470
Reads
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121
Citations
Citations since 2016
22 Research Items
91 Citations
2016201720182019202020212022051015202530
2016201720182019202020212022051015202530
2016201720182019202020212022051015202530
2016201720182019202020212022051015202530

Publications

Publications (41)
Article
Full-text available
At our institute a piston-driven shock tunnel is operated to investigate structures of space transportation systems under reentry and propelled flight conditions. For temperature measurements in the nozzle reservoir under single-shot conditions, laser-induced thermal grating spectroscopy is used to date to measure the speed of sound of the test gas...
Article
Boundary-layer disturbances on a cone in a hypersonic flow are investigated by heat flux sensors. The cone has a half-angle of 10.9 deg and is situated with a 0 deg angle of attack in a Mach 10 region of a conical nozzle in a shock-tunnel facility. There are three atomic layer thermopile heat flux sensors mounted at different chordwise positions in...
Article
Film cooling is a critical technology to reduce heat loads on gas turbine components. To improve the cooling performance, trench configurations have been developed. In this study, for the first time we experimentally examine the influence of mainstream turbulence and large vortices on trenched film cooling flows. We apply an imaging technique based...
Article
Full-text available
Experimental determination of test gas caloric quantities in high-enthalpy ground testing is impeded by excessive pressure and temperature levels as well as minimum test timescales of short-duration facilities. Yet, accurate knowledge of test gas conditions and stagnation enthalpy prior to nozzle expansion is crucial for a valid comparison of exper...
Conference Paper
Full-text available
Near-wall chemical reactions of gaseous transverse fuels in a hot, oxygen-rich crossflow were investigated experimentally by means of OH chemiluminescence, OH planar laser-induced fluorescence (PLIF) and average two-line PLIF thermometry. The heat flux released to the surface was determined using numerical solutions to the inverse heat conduction p...
Article
For the thermal design of combustion chambers and turbine blades in jet engines, a detailed knowledge of the combustion and of the heat loads to the walls is necessary. In general, high operating temperatures and reduced combustor size are striven for in order to increase engine efficiency and reduce weight. Consequently, the components are exposed...
Conference Paper
For the thermal design of combustion chambers and turbine blades in jet engines, a detailed knowledge of the combustion and of the heat loads to the walls is necessary. In general, high operating temperatures and reduced combustor size are striven for in order to increase engine efficiency and reduce weight. Consequently, the components are exposed...
Article
Full-text available
Gas turbine film cooling strategies must provide adequate cooling performance under high levels of mainstream turbulence. Detailed information about the structure, dynamics and transport of the cooling films is needed to understand the flow physics and develop suitable numerical simulation tools. Here, we study film cooling flows in a wind tunnel w...
Article
The effect of fuel temperature on the erosion intensity in micro-channels for different fuels like calibration fluid ISO 4113 and dodecane is investigated. A high-pressure closed loop test bench for fuels under elevated temperatures up to 160 °C is used to erode micro-channels made of Al 99.0 at a maximum pressure of 500 bar. The evaluation of the...
Article
The prevention of erosion caused by hydrodynamic cavitation plays an important role in the design of hydraulic components, such as fuel injection systems. A high pressure level and the corresponding flow speeds at a very small scale of several micrometers limit the optical accessibility in real fuel injectors. For this reason, flat micro-channels o...
Article
Full-text available
Free-piston shock tunnels are ground-based test facilities allowing the simulation of reentry flow conditions in a simple and cost-efficient way. For a better understanding of the processes occurring in a shock tunnel as well as for an optimal comparability of experimental data gained in shock tunnels to numerical simulations, it is highly desirabl...
Conference Paper
Cavitation erosion plays an important role in the development of new hydraulic components for fuel injection systems. Due to the high pressure level, the corresponding flow speed and limited optical accessibility in real fuel injectors, a test bench consisting of a high pressure generator and a 2D flow channel covered by sapphire windows is used. C...
Conference Paper
In modern gas turbines, heat loads on thermal highly stressed components are reduced by film cooling, where a layer of cold gas is injected for the protection of these components. In order to optimize present cooling designs, experiments under realistic operating conditions have to be performed especially including the effect of turbulence intensit...
Conference Paper
High-turbulence flow conditions in gas turbine combustors create a rough environment for film cooling flows. Fundamental knowledge of the interaction between main flow fluctuations and cooling jet is essential to develop more efficient cooling geometries. To gain detailed insight into the turbulent flow structures, high-speed PIV measurements have...
Article
Experimental determination of test gas temperature and enthalpy in ground testing is a challenging task, particularly regarding excessive pressure and temperature levels as well as minimum characteristic time scales available in transient facilities. Accurate knowledge of test gas conditions and stagnation enthalpy in reentry experiments is, howeve...
Article
The objective of the presented work was the investigation of two-photon laser-induced fluorescence excitation spectra of carbon monoxide (CO) molecules (B-X) in a carbon dioxide (CO2) flow with an enthalpy of 2.1 MJ/kg. The flow was generated with an arcjet-driven plasma wind tunnel. For validation, different stoichiometric premixed methane/air fla...
Article
Laser-induced fluorescence using the A-X(0,0) band for excitation of nitric oxide is a promising approach for examining high-enthalpy flows. Spectroscopic investigations within this excitation wavelength band intend to identify appropriate transitions that maximize the fluorescence signal and minimize possible interference with other species. Speci...
Conference Paper
To investigate structures of space transportation systems under reentry conditions, high-speed and high-enthalpy flows are simulated experimentally at the Institute for Thermodynamics at the University of the Federal Armed Forces Munich. To characterize flow conditions of the piston-driven shock tunnel, High-Enthalpy Laboratory Munich, laser-induce...
Conference Paper
Laser induced fluorescence using the A-X(0,0) band for excitation of nitric oxide (NO) is a promising approach to examine high enthalpy flow. Spectroscopic investigations within this excitation wavelength band intend to identify appropriate transitions that maximize fluorescence signal and minimize possible interference with other species. The rota...
Article
An optical setup for laser-induced grating spectroscopy is presented. This setup provides the possibility to induce and analyze electrostrictive gratings as well as thermal gratings. Switching between the techniques can be realized smoothly. Temperature measurements were carried out at different test gas conditions in a temperature range from 20 to...
Article
A new facility for the measurement of the normal spectral emissivity of solid materials for high-temperature applications in the thermal steady state was developed at the Bundeswehr University of Munich. The measurements are performed under atmospheric conditions. The facility covers the temperature range between $500\,^{\circ }\hbox {C}$ and...
Conference Paper
An optical setup for laser-induced grating spectroscopy is presented. This setup provides the possibility to detect electrostrictive gratings as well as thermal gratings. Temperature measurements were carried out at different test gas conditions in a temperature range from 20° C to 70° C and a pressure range from 1 bar to 20 bar using a test chambe...
Conference Paper
A first experimental setup of a Laser-Induced Electrostrictive Grating Spectroscopy system was built and temperature measurements in a pressure cell were carried out successfully for different pressures. Furthermore, experience was collected by varying some of the geometrical parameters of the setup. A discrete fast fourier transform was used to de...
Conference Paper
Spontaneous Raman spectroscopy can provide nonintrusive access to flow state properties like e.g. temperature and species concentration. In this article, a one-dimensional spontaneous Raman spectroscopy procedure is presented to measure local density and temperature distributions in hot gas environments. The method uses two energy levels of molecul...
Article
A novel injector was developed as the result of numerical and experimental studies of the self-ignition of hydrogen and the flame stabilization in a supersonic flow (Ma = 2.1, T-0 = 900 K). The injector was realized as a serial system of a conventional supersonic diffuser and a nozzle dividing the flow into two parts. Most of the air flows into the...
Article
Full-text available
The influence of radicals emitted by a vitiator into a model of a hydrogen-fueled scramjet combustor was investigated. The effect of the preheater combustion was analyzed by varying between a flame mode with high radical formation and a flame mode in which the concentration of the OH radicals was reduced below the detection limit of the optical sys...
Article
Full-text available
For the investigation of the ignition and reaction of fuel injected into the combustor of a Scramjet at a flight Mach number of 8 high temperature test air at supersonic speed is required. One economic possibility to simulate these inlet conditions experimentally is the use of vitiators which preheat the air by the burning of hydrogen. Downstream o...
Article
The results of a high pressure absorption, X-ray diffraction and Raman scattering study indicate a pressure induced phase transition in KTbP2Se6 at about 9.2GPa which is accompanied by a discontinuous jump of the absorption edge of about 0.5eV into the red. The phase transition is also reflected in the Raman spectrum at this pressure. The result of...
Article
For decreasing the transportation costs into the orbit, two staged propulsion systems with an air breathing lower grade is seen as a promising alternative to rocket-based systems. The problem realizing such a kind of propulsion is the short residence time of the gas mixture in the combustor. In this work, investigations using different injectors fo...

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