A5034539155- Gas Dynamics and Kinetic Theory
- Fluid Dynamics and Turbulent Flows
- Computational Fluid Dynamics and Aerodynamics
- Plasma and Flow Control in Aerodynamics
- Wind and Air Flow Studies
- Rocket and propulsion systems research
- Aerodynamics and Acoustics in Jet Flows
- Particle Dynamics in Fluid Flows
- Spacecraft and Cryogenic Technologies
- Combustion and Detonation Processes
- Fluid Dynamics and Vibration Analysis
- Aerodynamics and Fluid Dynamics Research
- Lattice Boltzmann Simulation Studies
- Spacecraft Dynamics and Control
- Aerogels and thermal insulation
- Aerospace Engineering and Control Systems
- Vehicle emissions and performance
- Heat and Mass Transfer in Porous Media
- Fiber-reinforced polymer composites
- Aerosol Filtration and Electrostatic Precipitation
- Energetic Materials and Combustion
- Fluid Dynamics and Thin Films
- Cellular and Composite Structures
- Space Satellite Systems and Control
- Spacecraft Design and Technology
Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)
2013-2024
Technische Universität Braunschweig
2010-2019
AMINAR-turbulent transition in hypersonic boundary layers remains a challenging subject.This is especially true of the hypervelocity regime, which an intriguing phenomenon possible damping second-mode disturbances by chemical and vibrational nonequilibrium processes 1,2 .To generate flows with sufficiently high enthalpy to investigate such effects, use shock-tunnel facilities necessary; furthermore, it now generally accepted that direct measurements instability mechanisms active within...
Axisymmetric direct numerical simulations of a spatially developing hypersonic boundary layer over sharp 7 deg half-angle cone at Reynolds numbers , and have been carried out. The streamwise extent the simulated domain is 0.9 m. excited with one-time application broadband pulse that advected downstream an impermeable wall complex impedance condition (IBC) modeling acoustic response carbon/carbon (C/C) ultrasonically absorptive porous surfaces. IBCs are derived as output pore-scale...
The acoustic second-mode instability predicted by linear stability theory is compared with direct numerical simulation for a hypersonic flow over various porous walls. damping effect of the micropores on second mode shown comparison two different approaches. In addition to investigating pore size, influence shape studied using spanwise grooves and cylindrical pores. Specifically, comparability shapes definitions hydraulic diameter analyzed. rarefied gas behavior inside pores also...
Abstract The influence of localized nitrogen transpiration on second mode instabilities in a hypersonic boundary layer is experimentally investigated. study conducted using $$7^\circ$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mn>7</mml:mn> <mml:mo>∘</mml:mo> </mml:msup> </mml:math> half-angle cone with length 1100 mm and small nose bluntness at $$0^\circ$$ <mml:mn>0</mml:mn> angle-of-attack. Transpiration realized through porous Carbon/Carbon patch $$44...
Three-dimensional numerical simulations of hypersonic boundary layer transition delay due to porosity representative carbon-fibre-reinforced carbon-matrix ceramics (C/C) were carried out on a 7 $^{\circ {}}$ half-angle cone for unit Reynolds numbers $Re_m=2.43 \times 10^6$ – $6.40\times 10^6\ \text {m}^{-1}$ , at the free-stream Mach number $M_\infty =7.4$ both sharp and 2.5 mm nose tip radii. A broadband time-domain impedance condition was used model acoustic effects porous surface flow...
In the present paper, several boundary-layer stability codes are compared, based on hypersonic, high-enthalpy flows around two different blunted cones: a 7° and 10.9° half-angle cone. One part of code-to-code comparison, which is conducted between seven codes, assesses influence numerical approaches for second-mode instability. The focus paper characterizes role real-gas effects second mode. experimental test cases comparison provided by wind tunnel facilities: High Enthalpy Shock Tunnel...
Previous investigations in the High Enthalpy Shock Tunnel Gottingen of German Aerospace Center (DLR) show that carbon fiber reinforced ceramic (C/C) surfaces can be utilized to damp hypersonic boundary layer instabilities resulting a delay transition onset. Linear stability analyses were performed using DLR code NOLOT, NOnLocal Transition analysis code. To adapt condition account for characteristics porous C/C material, ultrasonic absorption properties investigated experimentally and...
Hypersonic boundary-layer-transition is dominated by so-called Mack modes, second mode instabilities that can be damped passively acoustic absorptive coatings. Those coatings are realised in practise porous walls. In the present paper a stability analysis performed for boundary layer flow at Mach 6 over smooth wall and various The influence of porosity, radius thickness pores investigated. For this study three different codes used: linear code SLST University Southampton comparison with DLR...
Effects of porous carbon-fiber-reinforced carbon-matrix ceramics (C/C) on the stability second-mode waves a 7°-half-angle cone were investigated for Reynolds numbers Rem=2.43×106–6.40×106 m−1 at freestream Mach number M∞=7.4, both sharp and 2.5-mm-round nose tips. A broadband time-domain impedance boundary condition was used to model effects C/C porosity flow dynamics leveraging direct ultrasonic benchtop experiments homogenous absorber theory. spectral linear solver based orthogonal...
In the present study, three boundary-layer stability codes are compared based on hypersonic high-enthalpy flows around a blunted 7 deg half-angle cone. The code-to-code comparison is conducted between following codes: Nonlocal Transition analysis code of DLR, German Aerospace Center (DLR); Stability and Analysis for Boundary Layers VirtusAero LLC; VKI Extensible von Kármán Institute Fluid Dynamics. focuses role real-gas effects second-mode instability, in particular disturbance frequency,...
The potential of ultrasonically absorptive carbon fiber reinforced (C/C) based materials for passive boundary layer transition control on hypersonic flight vehicles is investigated. Based previous studies C/C, optimized C/C are developed and studied with respect to their temperature stability ultrasonic absorption properties at regimes interest. Generic vehicle shapes providing an essentially two dimensional flow field allowing the second mode instability be dominant using engineering...
The performance of hybrid rocket engines is significantly influenced by the fuel geometry. Burnback simulations, to determine surface and fluid volume, are therefore an important tool for preliminary design. This work presents a method simulation spatially constant burn-ups on arbitrary geometries. An implicit definition means signed distance function used represent volume block tetrahedral meshes. Two methods each burning surface. first based direct integration with Heaviside or Dirac delta...
<title>Abstract</title> In chemical propulsion, propellant masses are generally the largest part of overall weight. Hence, combustion efficiency is a key aspect system’s performance and small improvements within process can result in significant changes project costs or mission longevity. To analyze detailed physical processes, direct measurements cost-intensive limited to lab–scale devices. Numerical investigations have therefore become widely used tool simulate inner flow propulsion...
Hypersonic boundary-layer transition on a 7 • half-angle cone was investigated experimentally in the DLR High Enthalpy Shock Tunnel Göttingen (HEG) at Mach 7.5.The model, provided by Japan Aerospace Exploration Agency (JAXA), has length of 1100mm and tested with nose radii 2.25mm 5mm.The free stream unit Reynolds number varied over range 1.2 × 10 6 /m to 6.2 stagnation enthalpy H0 = 3.3M J/kg.The model equipped co-axial thermocouples determine location means surface heat-flux...
The present paper presents shock tube testing of the transpiration cooling experiment AKTiV flown on sub-orbital re-entry body SHEFEXII. campaign comprises a 1:3 subscale model at original Reynolds number, Mach number and velocity, so that subscaling has to be compensated for by rising gas density. This, in turn, results increased heat flux surface compared original. experiments are supported fluid dynamics computations code TAU. Moreover, lay out design transpiration-cooled thermal...
Abstract The Reusable Flight Experiment (ReFEx) is an experimental vehicle currently in development by the German Aerospace Center (DLR), which simulates reentry of a winged reusable booster stage. topic covered this paper aerodynamic design through Mach number range from 5.0 to 0.8, including transonic regime, CFD simulations using DLR TAU-Code. For steering and lift generation, equipped with multiple surfaces: canards, wings vertical fin. A VSB30 was chosen as carrier rocket, leading...
The influence of carbon fiber reinforced ceramic (C/C) surfaces on hypersonic boundary layer instabilities is analysed numerically using the stability code NOLOT, NOn-Local Transition analysis code, German Aerospace Center (DLR). Experimental investigations in DLR High Enthalpy Shock Tunnel Gottingen, HEG, show that C/C can be utilized to damp acoustic second mode instabilities, which results a delay transition onset. investigated geometry blunt 7° half-angle cone model with nose radius 2.5 mm...