Reducing Thermal Contact Resistance for Rigid Insulation Thermal Measurements

Daryabeigi, Kamran; Knutson, Jeffrey R.; Cunnington, G. R.

doi:10.2514/1.t3788

Cited by 8 publications

(4 citation statements)

References 13 publications

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“…Thermal contact resistance between the sample hot side and septum plate was ignored, and it was assumed that the septum plate and sample hot side temperatures were equal. Even though this assumption may not be strictly valid, its use had previously 26 resulted in thermal conductivity predictions for the LI-900 rigid silica insulation that had matched historical published data. 27 The cold side of the rigid test samples was instrumented with 3 to 6 flush mounted thin stainless steel foil thermocouples to provide the average sample cold-side temperature.…”

Section: B Effective Thermal Conductivity Measurementsmentioning

confidence: 94%

“…A thin layer (1.6 mm thick) of liquid bismuth alloy was also used between the top of the water-cooled plate and the bottom of the rigid insulation test sample to eliminate thermal contact resistance between the sample and water-cooled plate. 26 The planar area of the water-cooled and septum plates is 304.8  304.8 mm. The water-cooled plate is equipped with nine flushmounted thin-film heat flux gages that provide simultaneous heat flux and temperature measurements, while the septum plate is instrumented with 23 metal-sheathed thermocouples.…”

Section: B Effective Thermal Conductivity Measurementsmentioning

confidence: 99%

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Heat Transfer Modeling for Rigid High-Temperature Fibrous Insulation

Daryabeigi

Cunnington²,

Knutson

2012

43rd AIAA Thermophysics Conference

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Combined radiation and conduction heat transfer through a high-temperature, highporosity, rigid multiple-fiber fibrous insulation was modeled using a thermal model previously used to model heat transfer in flexible single-fiber fibrous insulation. The rigid insulation studied was alumina enhanced thermal barrier (AETB) at densities between 130 and 260 kg/m 3 . The model consists of using the diffusion approximation for radiation heat transfer, a semi-empirical solid conduction model, and a standard gas conduction model.

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Section: B Effective Thermal Conductivity Measurementsmentioning

confidence: 94%

Section: B Effective Thermal Conductivity Measurementsmentioning

confidence: 99%

Heat Transfer Modeling for Rigid High-Temperature Fibrous Insulation

Daryabeigi

Cunnington²,

Knutson

2012

43rd AIAA Thermophysics Conference

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“…Daryabeigi et al [9] presented a measurement and prediction model for the thermal conductivity of Saffil fibrous insulation but neglected the thermal contact resistance (TCR). Moreover, Daryabeigi et al [10,11] utilized a liquid bismuth alloy at the contact surface to eliminate TCR. The experiment was carried out in an environment with pressure varying from 1.33´10 23 kPa (outer space conditions) to 101.32 kPa (atmospheric pressure) and without any surface compression load.…”

Section: Introduction and Literature Reviewmentioning

confidence: 99%

Experimental and Numerical Analysis of Thermal Resistance and Thermal Conductivity in Silica Fibrous Insulation Material at High Temperatures

Mirsharipov

2024

Preprint

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This study presents an in-depth experimental and numerical analysis of thermal resistance and effective thermal conductivity in silica dioxide fibrous insulation materials under high-temperature conditions. The primary objective was to accurately measure thermal properties to ensure the safety and integrity of structures subjected to extreme temperatures, such as rocket exteriors. A steady-state experimental approach was employed to determine the thermal behavior of the silica fibrous sample. Subsequently, a comprehensive 3D model was developed to simulate these conditions, allowing for a detailed comparison between experimental findings and numerical predictions. The results demonstrated a significant correlation between the experimentally obtained data and the simulations, highlighting the reliability of the numerical model in predicting the thermal behavior of silica fibrous insulation materials. The conclusion drawn from this research underscores the critical importance of precise assessment of thermal conductivity and thermal resistance in high-temperature insulation materials. Accurate evaluations are essential for the design and safety of rocket structures, as they significantly influence the thermal protection system's effectiveness. This study not only contributes to the understanding of silica fibrous materials' thermal properties but also provides a validated methodological framework for future research in the thermal analysis of insulation materials.

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“…2 These materials can withstand high temperatures of about 2000 °C and severe aerodynamic thermal/structural loads. Rigid fiber insulation materials 3 are most suitable for use in windward surfaces, flaps, and control surfaces where temperatures reach 900−1300 °C, while fiber insulation materials are generally used for the leeward surface of an aircraft's wings and fuselage, where temperatures are only 320−800 °C. This study focuses on researching thermal protection materials used on the leeward surface of aircrafts.…”

Section: Introductionmentioning

confidence: 99%

Mechanically Robust Nanoporous Polyimide/Silica Aerogels for Thermal Superinsulation of Aircraft

Zhang

Wang

et al. 2023

ACS Appl. Nano Mater.

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Polyimide aerogels (PIAs) are thermally insulating materials that possess various advantages, such as exceptionally high temperature resistance and low thermal conductivity, which make them great potential candidate materials to be applied in the area of thermal protection. However, under harsh mechanical stresses, the macro- and microscopic structural stability of PIAs may be compromised due to shrinkage/collapse, leading to performance degradation. Herein, we propose a homogeneous organic/inorganic hybrid formation strategy for constructing nanoporous polyimide/silica aerogels (PIAs-A) with exceptional mechanical strength and ultralow thermal conductivity. The results obtained indicate that PIAs-A have an optimal three-dimensional nanoporous network structure with a pore size distribution mainly within the range of 10–20 nm. Monitoring the temperature evolution of the material’s cold surface showed that it remained at a low temperature of 37.5 °C even when the material was placed against a hot surface of 150 °C. The residual mechanical strengths of the aerogels remained at a superior level (with strength degradation being less than 9%) after exposure to ultralow and high-temperature atmospheres. Furthermore, compressive stress values at 3% strain exceeded previously reported values for PIAs by 625 and 733% at −50 and 100 °C, respectively. Meanwhile, our aerogels displayed flame resistance even when exposed to a heat source of approximately 1200 °C, possessed favorable hydrophobic properties, and maintained dimensional stability up to 504 °C. The robust mechanical and thermal insulation properties of PIAs-A make them a promising substitute material for thermal superinsulation in aircraft.

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Reducing Thermal Contact Resistance for Rigid Insulation Thermal Measurements

Cited by 8 publications

References 13 publications

Heat Transfer Modeling for Rigid High-Temperature Fibrous Insulation

Heat Transfer Modeling for Rigid High-Temperature Fibrous Insulation

Experimental and Numerical Analysis of Thermal Resistance and Thermal Conductivity in Silica Fibrous Insulation Material at High Temperatures

Mechanically Robust Nanoporous Polyimide/Silica Aerogels for Thermal Superinsulation of Aircraft

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