Heat Balance of a Transpiration-Cooled Heat Shield

Boehrk, Hannah; Piol, Olivier; Kuhn, Markus

doi:10.2514/6.2009-7273

Cited by 8 publications

(16 citation statements)

References 6 publications

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“…Transient wall temperature determination has been validated for transpiration-cooling by comparison with experiments of the RESPACE and IMENS + test campaigns [6]. The heat balance for the surface in the case of pure aerodynamic heating equalṡ…”

Section: Heat Balancementioning

confidence: 99%

“…(10) and (11) are the Stanton number St and the recovery factor r. They must be determined for each flow condition, be it laminar or turbulent. For laminar flow this is done based on known models of Crocco and van Driest [14,15,6]. The Stanton number for solution of eq.…”

Section: Heat Balancementioning

confidence: 99%

“…This way, the temperature response of the structure is determined for the uncooled case as well as for the coupled film-and convection cooled conditions. It has been validated by comparison to experiments in an arc-heated wind tunnel under laminar in-flow [6,7]. Complementary to the filght data evaluation, a comparison of the measurement and results from HEATS is introduced and discussed.…”

Section: Introductionmentioning

confidence: 99%

“…Especially when the surface is actively cooled, such as with film-, transpiration-, or effusion-cooling, the determination of the heat transfer coefficient is difficult to assess [5]. The computer program HEATS (Heat Exchange Analysis for Transpiration Systems) is introduced, here, serving to solve the heat balances of the vehicle structure [6]. It determines transient wall temperature throughout an entire re-entry trajectory or ground-testing experiment at short calculation time including inert thermal response of the material, so that overdesign can be minimized.…”

Section: Introductionmentioning

confidence: 99%

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Transpiration Cooling at Hypersonic Flight - AKTiV on SHEFEX II

Böhrk

2014

11th AIAA/ASME Joint Thermophysics and Heat Transfer Conference

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The present paper presents the in-flight measurement of the transpiration cooling experiment AKTiV flown on the sub-orbital re-entry configuration SHEFEX II. Thermal response of the structure is measured just up-and downstream of a cooled sample with a non-cooled reference set-up on the opposite side of the vehicle. The measurement shows that the heat flux is reduced upon coolant exhaust. The maximum temperature reduction by transpiration-cooling is observed on the porous sample with 87 K, while downstream the sample, the temperature reduction by film cooling is 75 K. This corresponds to cooling efficiencies of 61% and 46% on the sample and downstream, respectively. The evaluation is supported by the semi-analytical tool HEATS, based on a transient heat balance at the surface. Comparison of the results with HEATS shows that the heat flux predicted with HEATS is in good concurrence with the measured temperatures on the cooled sample, as well as upstream and downstream with a maximum deviation by 14%. The analysis shows that the flow condition around the sharp-edged, faceted vehicle remains longer laminar than expected.

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Section: Heat Balancementioning

confidence: 99%

Section: Heat Balancementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Transpiration Cooling at Hypersonic Flight - AKTiV on SHEFEX II

Böhrk

2014

11th AIAA/ASME Joint Thermophysics and Heat Transfer Conference

Self Cite

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“…In addition, a numerical approach is presented and validated with the measured data. For this purpose the numerical code HEATS [3] will be adapted to compute the two-dimensional pressure distribution of the porous cone geometry. Finally, to design and layout a transpiration-cooled sharp leading edge or tip, it is essential to have the knowledge of the key parameters which are responsible for the outflow behavior of such permeable material and the ideal transpiration-cooled geometry.…”

Section: Introductionmentioning

confidence: 99%

Characterization of the Flow Field of Anisotropic Porous Cones with Different Wall Thickness

Dittert

Selzer

Böhrk

2015

20th AIAA International Space Planes and Hypersonic Systems and Technologies Conference

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In hypersonic flight, sharp body concepts have several advantages compared to the classic blunt approach. Conversely, the heat load on the sharp leading edge is significantly increased. Therefore, it is necessary to consider active cooling concepts for the sharp leading edge. In this paper a transpiration-cooled cone is investigated with focus on the varying cooling mass flow along the surface, caused by anisotropic permeability of the material, and increasing wall thickness. Two cones with different angles are investigated with respect to their cooling flow behavior in the DLR test facility AORTA, which was built to characterize porous material. The measurements include the dynamic pressure distribution at the surface, in addition to reservoir pressure and the total mass flow. Furthermore a numerical approach is presented to simulate the pressure loss over the wall thickness with the two-dimensional Darcy equation and the mass flow distribution at the surface. Finally, the results from the experiment and the simulation are presented and assessed with respect to the fiber orientation of the material. The results show clear trends of mass flow distribution along the circumference of the cone. These mass flow distributions can be explained by the flow dependence of the fiber orientation and the resulting permeability.

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Probabilistic constrained Bayesian inversion for transpiration cooling

Steins

Bui‐Thanh²,

Herty

et al. 2022

Numerical Methods in Fluids

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To enable safe operations in applications such as rocket combustion chambers, the materials require cooling to avoid material damage. Here, transpiration cooling is a promising cooling technique. Numerous studies investigate possibilities to simulate and evaluate the complex cooling mechanism. One naturally arising question is the amount of coolant required to ensure a safe operation. To study this, we introduce an approach that determines the posterior probability distribution of the Reynolds number using an inverse problem and constraining the maximum temperature of the system under parameter uncertainties. Mathematically, this chance inequality constraint is dealt with by a generalized polynomial chaos expansion of the system. The posterior distribution will be evaluated by different Markov chain Monte Carlo based methods. A novel method for the constrained case is proposed and tested among others on two‐dimensional transpiration cooling models.

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Heat Balance of a Transpiration-Cooled Heat Shield

Cited by 8 publications

References 6 publications

Transpiration Cooling at Hypersonic Flight - AKTiV on SHEFEX II

Transpiration Cooling at Hypersonic Flight - AKTiV on SHEFEX II

Characterization of the Flow Field of Anisotropic Porous Cones with Different Wall Thickness

Probabilistic constrained Bayesian inversion for transpiration cooling

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