Christian Mundt

Christian Mundt
Universität der Bundeswehr München · LRT 10

About

107
Publications
10,203
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390
Citations
Citations since 2016
44 Research Items
232 Citations
2016201720182019202020212022010203040
2016201720182019202020212022010203040
2016201720182019202020212022010203040
2016201720182019202020212022010203040
Introduction
Skills and Expertise

Publications

Publications (107)
Conference Paper
Full-text available
During flight of propelled hypersonic vehicles, a strong interaction between the hypersonic flow around the vehicle and the nozzle exhaust plume takes place. The interaction affects the entire structure of the flow behind of the vehicle, altering both aerodynamic performance and stability. Generic slender vehicle geometries with and without a propu...
Article
An advanced multi-color surface oil flow technique is used to visualize the wall shear stress distributions on two different wind tunnel models in transonic as well as supersonic flow conditions reaching from Mach 0.9 to Mach 2.0. The results of the visualizations are superpositioned by numerically calculated wall shear stress distributions. Not on...
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...
Conference Paper
An experimental method for the determination of the pitch damping moment coefficient sum Cmq + Cm in a wind tunnel is presented. A low-interference wire suspension is used, thus enabling the investigation of projectile configurations in wind tunnels with a low-diameter test section at transonic Mach numbers. Two reference models, the Basic Finner a...
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
Full-text available
A fully conservative overset mesh method is proposed and applied to overcome the metric singularity at the symmetry line for blunt bodies, e.g., capsules and blunted cones, in general curvilinear coordinates. The overset mesh is placed automatically at the symmetry line by avoiding the collapse of the grid lines using a hexahedral structure in cont...
Article
Full-text available
An experimental method for the determination of the pitch damping moment coefficient sum Cmq+Cmα˙ in a wind tunnel at transonic and low supersonic Mach numbers is developed. With support interference being a major issue for dynamic tests at these velocities, a minimum interference wire suspension approach is used. The motion of the wind tunnel mode...
Article
Frictional contact results in dissipation of energy, wherein one part is transformed into thermal energy. This leads to heating under the surface, where the resulting transient temperature fields at short times and high Peclet numbers are of interest. Therefore, the numerical method of finite elements with space-time stabilization technique is appl...
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
An experimental method for the determination of the pitch damping moment coefficient sum in a wind tunnel suitable for small model sizes at subsonic and transonic Mach numbers is presented. The models are mounted by a wire suspension support system and a free-decay approach is used. Two reference models, the Basic Finner and the Army-Navy Spinner R...
Conference Paper
Full-text available
The thermal state of the wall is one of the most crucial parameters for the design ofhypersonic vehicles. It is strongly affected by turbulence in high Reynolds number conditions.RANS models are widely applied in many applications due to their efficiency compared tomore sophisticated approaches. In this publication, the performance of popular RANS...
Article
Purpose Spinning slender bodies are affected by lateral Magnus forces and moments when exposed to cross-flow. The effects occurring for spinning bodies of revolution in combination with stabilising or control surfaces such as canards are not yet fully explained. Therefore the present work aims to investigate the phenomena arising from the interacti...
Chapter
The generation of side forces and yawing moments on three bodies of revolution with different types of canted fins is studied by means of 3D compressible Reynolds-averaged Navier-Stokes (RANS) simulations and wind tunnel measurements at Mach 2 and angles of attack between \(0^{\circ }\) and \(20^{\circ }\). The analysis of flow structures and the l...
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...
Article
A full three-dimensional photon Monte Carlo radiative transport solver, named StaRad, is developed to calculate thermal radiative heat flux and infrared signatures within equilibrium and nonequilibrium hypersonic flows. The code is developed to investigate arbitrary thermal radiative transport and is line-by-line accurate. The solver makes use of a...
Article
The Mars atmosphere, consisting mainly of CO2, with a few percent of N2 and other trace gases, is of interest to future space projects. Entry into its gaseous shell is of current significant research interest. For this application, an arc jet driven plasma wind tunnel is available to simulate relevant entry conditions for the planet. Recent improve...
Conference Paper
Full-text available
Even after decades of experience, the numerical simulation of heated and unheated supersonic jets into a resting fluid remains a challenging task. The reasons fall into two categories: solver- and turbulence model related problems. Solving techniques for supersonic flows show a bad convergence behavior in subsonic regions. On the other hand, incomp...
Article
This paper presents an overview of a toolbox that has been developed and validated to aid the development process of future space-launch vehicles. The primary focus lays on structure, geometry, and thermal protection optimization in the early design phase of a cryogenic launcher stage. It is thereby irrelevant whether the envisaged stage operates f...
Conference Paper
Full-text available
The space launch industry is a very competitive business, especially nowadays with many private companies entering the market. Due to economic pressures, existing launch vehicles are under constant evolution to minimize cost, maximize payload capabilities, and enhance reliability. Entire new developments from scratch and the introduction of fundame...
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...
Chapter
Re-entry flights in carbon dioxide–nitrogen atmospheres such as Mars and Venus became more and more the focal point of interest in the research community lately. During these re-entry flights at hypersonic velocities, a high-enthalpy flow field is generated behind the bow shock. Due to this high-enthalpy flow field, the constituent chemical species...
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...
Conference Paper
Full-text available
Two set-points of the Acoustic Reference Nozzle 2 experiment, representing an unheated and a heated subsonic jet, are investigated numerically. The far-field noise spectra are calculated using two different CAA approaches. The first method is based on scale-resolving simulations (SRS). It exhibits a low degree of modeling and is therefore universal...
Conference Paper
Full-text available
Comparisons with experiments have shown that RANS models tend to underpredict the mixing process in shear layers with strong temperature gradients. In the modeling of jet engine's exhaust systems this leads to an overpredicted potential core length and underestimated turbulence intensity in the free jet. In addition , the calculated efficiency gain...
Article
Full-text available
This article describes experimental results and the numerical validation for multiphase, multicomponent evaporation in porous media 1d flow. We apply the model of Lindner et al. (Transp. Porous Media 112(2):313–332, 2016. doi:10.1007/s11242-016-0646-6). The permeability of the porous medium is measured in an additional setup with a constant head pe...
Chapter
The simulation of high enthalpy, hypersonic flows is a field of continued research efforts and provides a difficult task despite all progress made in the past years. This is the case for both experimental and numerical simulations of the real flight of a high speed vehicle, typically either winged or un-winged re-entry configurations, high speed ai...
Conference Paper
Full-text available
Thermal stratification in cryogenic fuel tanks is a recurring topic due to the recent decisions on new developments of next generation launch vehicles. The complexity of mechanisms involved and the inaccessibility to measurements under realistic conditions make it hard to gain fundamental understanding and consequently to make accurate predictions....
Article
Recently, the ESA started the development of the successor for the Ariane 5 launcher system, the Ariane 6. In this context, previously discussed but never realized technologies get attention again. This applies to common bulkhead cryogenic fuel tank geometries for upper stages, which are also further investigated in this paper. Requirements for a l...
Conference Paper
Full-text available
Due to constantly increasing flight traffic the aircraft industry is faced with major challenges. Essentially these are reduction of fuel consumption and noise emission. The latter plays an outstanding role in the vicinity of airports where residents are subjected to increased noise disturbance. Strict regulations protect these citizens and force a...
Article
This article investigates the evaporation process in porous media during transpiration cooling. This means that a strong heat source fully evaporates a high liquid flux, leading to complex flow situations. This multiphase flow with phase change setting is simulated with two different models, implemented in MATLAB R ⃝ and DuMu x , a free and open so...
Conference Paper
Full-text available
The steering of supersonic vehicles and projectiles can be done by producing an asymmetry of the flow surrounding them. One possible technique is to steer a projectile on demand by using an embedded DC-plasma actuator. The actuator induces electric discharges generating plasma on the projectile surface. Although many measurements have been carried...
Article
Full-text available
For multiphase, multicomponent flow, the multiphase mixture model of Wang and Cheng (Int J Heat Mass Trans 39(17):3607–3618, 1996) has been used in the literature. In our self-written solver, based on this mathematical background, we use a modified multiphase mixture model for a simple transpiration cooling application. In this modeling approach, w...
Article
Full-text available
Corresponding to Oswatitsch’s Mach number independence principle the Mach number of hypersonic inviscid flows, ∞ ≈> Ma 5 , does not affect components of various non-dimensional formulations such as velocity and density, pressure coefficients and Mach number behind a strong shock. On this account, the principle is significant in the development proc...
Conference Paper
Full-text available
Der Einsatz von Blütenmischern in Turbofantriebwerken mit kleinen und mittleren Nebenstromverhältnissen ist seit längerem eine gängige Methode, um sowohl die Leistungs-, als auch die Lärmcharakteristik von Flugzeugen zu verbessern. Zur Optimierung solcher Bauteile werden zunehmend numerische Verfahren verwendet, da diese oft deutliche Kosten- und...
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...
Article
One of the major problems facing the users of aircraft engines and stationary gas turbines in dusty and dirty environments is erosion, causing engine performance deterioration. Thermal barrier coatings (TBCs) are often applied on metal engine components as combustor heat shields or tiles as well as turbine blades allowing enhanced operating tempera...
Article
This article investigates the multiphase flow in a porous channel, heated at one section of the wall. For non-isothermal flow with phase-change, a finite-volume solver in MATLAB® is used with a two-phase mixture model with local thermal non-equilibrium , i.e., allowing for different solid- and fluid temperatures locally. The effect of gravity is ex...
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
An approach is proposed to improve numerical modeling of directional thermal radiation originating from absorbing, emitting and scattering media. In this approach, the finite volume method for radiation transfer is applied on the narrow-band basis to evaluate the source function of the radiative transfer equation. The emission in a given direction...
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
Radiative heat transfer is analyzed for subscale and fullscale rocket combustion chambers for H2/O2 and CH4/O2 combustion using the P1 radiation transport model in combination with various Weighted Sum of Gray Gases Models (WSGGMs). The influence of different wall emissivities, as well as the results using different WSGGMs, the size of the combusti...
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
The development of more efficient and environmentally friendly powerplants for air transportation is getting more and more challenging. Therefore a deep understanding of all components of an aeroengine is necessary to fulfill the increasing requirements. One of these components is the exhaust system, which is the focus in this study. The flow throu...
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
The narrowband correlated-k method is applied to numerical simulation of IR emissions from the exhaust plume of a typical turbofan engine. The Spectral Radiation Calculation Software module is coupled with the ray-tracing radiative transfer equation solver to provide the k-distribution data retrieval for each narrowband. In the simulations performe...
Article
Full-text available
Background. New aerosol drugs for infants may require more efficient delivery systems, including face masks. Maximizing delivery efficiency requires tight-fitting masks with minimal internal mask volumes, which could cause carbon dioxide (CO(2)) retention. An RNA-interference-based antiviral for treatment of respiratory syncytial virus in populatio...
Conference Paper
The FIRE II flight test is simulated using the CFD code NSMB. Several models for chemical nonequilibrium, the equilibrium constant, thermal nonequilibrium and transport properties are tested and their results in convecti ve wall heat flux are compared to those by former investigators. Using the results of NSMB, a 1D radiative heat transfer analysis...
Conference Paper
Infrared (IR) emission properties of nonscattering exhaust plumes of realistic aircraft engines are studied and analyzed in this paper by means of numerical simulations applying statistical narrowband (SNB) models. A review of the model parameters generated by various authors is given. Different factors affecting the plume IR signature simulation s...
Article
More efficient and environmental friendly powerplants for air transportation are required. Therefore a deep understanding of all components of an aeroengine is necessary to fulfil the increasing requirements. One of these components is the exhaust system, which is the focus in this study. The flow through the nozzle system with installed lobed forc...
Article
In this work, enhanced Weighted Sum of Gray Gases Models for spectral integration of radiative heat transfer are identified and implemented in the Computational Fluid Dynamics solver ANSYS CFX. The models are applicable to both homogeneous and nonhomogeneous conditions in temperature, pressure and molar fraction of radiating species. A simulation o...
Conference Paper
Full-text available
MIRIAM, short for ‘Main Inflated Re-entry Into the Atmosphere Mission test’, is a validation concept designed for the Mars ballute technology development programme ARCHIMEDES. This development programme is a joint effort of the Mars Society Germany and the University of the Federal Armed Forces of Germany in Munich, with further support by research...
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...