Convective and radiative heat transfer to an ablating body

Hoshizaki, H.; Lasher, L. E.

doi:10.2514/6.1967-327

Cited by 15 publications

(3 citation statements)

References 10 publications

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“…Most polymeric ablators are based on thermosetting resins reinforced with carbon fibres (CFs), ceramic particles and carbon nanostructures [3]. Convective heat flux on the ablation surface is transmitted by conduction from the outer surface of the thermal protection systems [4]. Consequently, decomposition occurs at the pyrolysis temperature of the matrix and producing gaseous products and a porous residue as char [5].…”

Section: Introductionmentioning

confidence: 99%

Comparison of weight‐loss changes with different compositions of ZrB ₂ nanoparticles in carbon fabric–novolac composite at high temperature

Amirsardari

Aghdam

2017

Micro & Nano Letters

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To improve the thermal properties of novolac resin, zirconium diboride (ZrB 2) nanoparticles (ZNP) with different weight percentages (0, 2, 4 and 7) were introduced into novolac resin. ZrB 2 nanoparticles modified carbon-novolac (C-N) composites were used to determine and compare the ablation performance, thermal stresses and cracks, and mechanical properties of these modified polymer composites. Thermal protection via ablation was achieved through a self-regulating heat and mass transfer process involving an insulator with low thermal conductivity and concomitant formation of a hard char on the insulator surface after 160 s exposure to the combustion environment. Anti-oxidation mechanisms for the novolac resin modified with nanoparticles at different weight percentage were compared and discussed. Ablation performance shows a steady increase with the filler content until a maximum, at 4 wt% of ZNP, and then it decreases.

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Section: Introductionmentioning

confidence: 99%

Comparison of weight‐loss changes with different compositions of ZrB ₂ nanoparticles in carbon fabric–novolac composite at high temperature

Amirsardari

Aghdam

2017

Micro & Nano Letters

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“…The only successful concept for thermal protection at these load levels is ablation. Heat shields consisting of ablative materials withstand the high heat loads through a combination of several effects: the hot surface reduces the heat transfer at the wall and increases the reradiation of heat; pyrolysis processes inside the material lead to an outgassing that keeps the hot plasma flow (further) away from the surface; and chemical and thermal decomposition consumes heat through oxidation, nitridation, and sublimation [2][3][4][5]. At the Institute of Space Systems (IRS) of the University of Stuttgart, plasma wind tunnels have been developed to provide high-enthalpy plasma flows for fundamental thermal protection material testing [6][7][8][9].…”

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confidence: 99%

Characterization of a Reentry Plasma Wind-Tunnel Flow with Vacuum-Ultraviolet to Near-Infrared Spectroscopy

Hermann

Löhle

Zander

et al. 2016

Journal of Thermophysics and Heat Transfer

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This paper presents the analysis of optical emission spectroscopic measurements from vacuum ultraviolet (120 nm) to near infrared (960 nm) in a high-enthalpy air plasma flow corresponding to superorbital reentry conditions. The vacuum ultraviolet measurements have been realized with a new experimental setup allowing measurements through a bore hole in the sample. Using the commonly applied optical emission spectroscopy from the side, the radiation transport along the line of sight of the vacuum ultraviolet measurements has been assessed. This allowed the determination of the local ground state densities of atomic oxygen and atomic nitrogen from a branching ratio analysis and the blackbody limiting correction of the vacuum ultraviolet radiation. Through the analysis of the absorption in the borehole, the spectra have been corrected, resulting in a stagnation point radiative heat flux in the vacuum ultraviolet of 235 kW∕m 2 .= local mass-specific enthalpy, MJ∕kg I = arc current, A K = proportionality constant for air, W∕MJ∕kg·Pa 0.5 ·m 1.5 k = Boltzmann constant, J∕K k cal = calibration factor, W∕m 2 · nm · sr∕counts∕s L λ = spectral radiance, W∕m 2 · nm · sr L λ;Limit = blackbody limit spectral radiance, W∕m 2 · nm · sr M = magnification _ m = mass flow, g∕s n = number density, m −3 n i = excited state population density, m −3 n 0 = ground state population density, m −3 P = electric power, kW P k = spectral line shape, nm −1 p = pressure, hPa _ q = heat flux, kW∕m 2 R eff = effective nose radius, mm r = radial distance, mm S = raw signal, counts/s s = distance from the probe surface, mm s 0 = distance between object and focusing element, mm= vibrational quantum number x = axial distance from the nozzle, mm y = horizontal distance from the nozzle, mm z = vertical distance from the nozzle, mm α λ = absorption coefficient, m −1 δ = full width at half-maximum of line broadening, nm ε λ = emission coefficient, W∕m 3 · nm · sr ε = spectrally integrated emission coefficient, W∕m 3 · sr λ = wavelength, nm σ λ = absorption cross section, m 2 Subscripts BB = blackbody DL = deuterium lamp exc = electronic excitation IS = integrating sphere l = lower state rot = rotational tot = total trans = translational u = upper state vib = vibrational

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“…In order to protect the vehicle from these thermal loads, ablative heat shields are used. The introduction of carbonaceous and phenolic species originating from the ablative heat shield can have an effect on all energy transport mechanisms [6][7][8][9].…”

mentioning

confidence: 99%

Influence of Ablation on Vacuum-Ultraviolet Radiation in a Plasma Wind Tunnel Flow

Hermann

Löhle

Fasoulas

et al. 2017

Journal of Thermophysics and Heat Transfer

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Plasma wind tunnel experiments have been performed simulating a Hayabusa reentry trajectory point at 78.8 km altitude with a velocity of 11.7 km/s corresponding to a local mass-specific enthalpy of 68.4 MJ/kg and a stagnation pressure of 2.44 kPa. Ablation-radiation coupling is investigated using a carbon preform sample, a lightweight carbon phenolic ablator sample and cooled copper. Optical emission spectroscopic measurements in the vacuum ultraviolet (VUV) regime (116 nm-197 nm) have been conducted through a bore hole in the stagnation point of the different samples. Optical emission spectroscopic measurements in the UV/VIS spectral range (320 nm-810 nm) have been conducted viewing the plasma from the side. The stagnation point VUV radiation to the carbon preform sample is strongest while it is weakest for the carbon phenolic sample. In the UV/VIS both carbon based material sama PhD student, High Enthalpy Flow Diagnostic Group, IRS, Member AIAA

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Convective and radiative heat transfer to an ablating body

Cited by 15 publications

References 10 publications

Comparison of weight‐loss changes with different compositions of ZrB ₂ nanoparticles in carbon fabric–novolac composite at high temperature

Comparison of weight‐loss changes with different compositions of ZrB ₂ nanoparticles in carbon fabric–novolac composite at high temperature

Characterization of a Reentry Plasma Wind-Tunnel Flow with Vacuum-Ultraviolet to Near-Infrared Spectroscopy

Influence of Ablation on Vacuum-Ultraviolet Radiation in a Plasma Wind Tunnel Flow

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Convective and radiative heat transfer to an ablating body

Cited by 15 publications

References 10 publications

Comparison of weight‐loss changes with different compositions of ZrB 2 nanoparticles in carbon fabric–novolac composite at high temperature

Comparison of weight‐loss changes with different compositions of ZrB 2 nanoparticles in carbon fabric–novolac composite at high temperature

Characterization of a Reentry Plasma Wind-Tunnel Flow with Vacuum-Ultraviolet to Near-Infrared Spectroscopy

Influence of Ablation on Vacuum-Ultraviolet Radiation in a Plasma Wind Tunnel Flow

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Comparison of weight‐loss changes with different compositions of ZrB ₂ nanoparticles in carbon fabric–novolac composite at high temperature

Comparison of weight‐loss changes with different compositions of ZrB ₂ nanoparticles in carbon fabric–novolac composite at high temperature