Plasma Sprayed Ultra High Temperature Ceramics for Thermal Protection Systems

2000 ◽  
Author(s):  
T. Valente ◽  
C. Bartuli ◽  
G. Visconti ◽  
M. Tului
Keyword(s):  
Plasma Spraying ◽  
High Performance ◽  
Thermal Protection ◽  
Electrical Discharge Machining ◽  
High Heat ◽  
Heat Fluxes ◽  
Space Vehicles ◽  
Ultra High Temperature Ceramics ◽  
Protection Systems ◽  
Plasma Sprayed

Abstract Reusable space vehicles, which must withstand re-entry into the Earth's atmosphere, require external protection systems (TPS) which are usually in the forms of rigid surface in areas of high or moderate working temperature. High heat fluxes and temperatures related to high performance hypervelocity flights also require the use of TPS materials having good oxidation and thermal shock resistance, dimensional stability, and ablation resistance. Components by these materials are usually fabricated, starting from either billets or plate stocks, by uniaxial hot pressing, and complex parts, such as low radius edges, are then obtained by electrical discharge machining technique. This article investigates an alternative fabrication technology, based on plasma spraying, to produce near net shape components. Results of experimental activities, such as optimization of plasma spraying parameters based on a DOE approach, are reported and discussed.

scholarly journals Editorial: Ultra High Temperature Ceramics for Aerospace Applications

2010 ◽  
Vol 3 (1) ◽  
pp. 9-9
Author(s):  
Raffaele Savino
Keyword(s):  
High Temperature ◽  
High Speed ◽  
Thermal Protection ◽  
Space Vehicles ◽  
Component Level ◽  
Ultra High Temperature Ceramics ◽  
Thermal Protection Systems ◽  
Protection Systems ◽  
The Subject ◽  
Ultra High Temperature

Improved interest in ultra-high-temperature ceramics (UHTCs) is being animating the scientific community. This emerging attention is driven by the demand of developing re-usable hot structures as thermal protection systems of aerospace vehicles, able to re-enter in planetary atmospheres at relatively high speed (order of 8-11 Km/s). In contrast to traditional blunt capsules or Shuttle-like vehicles, characterised by poor gliding capabilities and complex thermal protection systems, the future use of UHTCs opens new horizons for the development of spaceplanes with slender fuselage noses and sharp wing leading edges. Advanced aerodynamic configurations reduce the vehicles drag, enhance the vehicles performances, due to a larger manoeuvrability resulting in larger down range, cross range and abort windows, and reduce electromagnetic interferences and communications black-out. Analysis has shown that materials with temperature capability approaching 2000°C and above will be required for these space vehicles, but the state of the art Reinforced Carbon-Carbon (RCC) material, currently used on the Space Shuttle, have maximum use temperatures of approximately 1650°C. The articles collected in this issue provide state-of-art scientific advancements on the subject with particular attention to the potential technological applications. The papers specifically deal with research studies on monolithic ceramic materials, composed primarily of Zirconium and Hafnium Diborides with different additives. The activities are carried out at materials level, with furnace or arc-jet testing, or include developments of UHTC-based hot structures at sub-component level. In the latter case, ultra-high temperature ceramic prototype structures have been developed and tested with embedded structural health monitoring systems. I want to thank all the article contributors for their manuscripts. I hope they will be useful for future basic and applied researches on the subject.

Precursor Influence on the Obtention of β-SiC Hollow Fibers

2008 ◽  
Vol 591-593 ◽  
pp. 578-582
Author(s):  
Luiz Eduardo Carvalho ◽  
Marcio Florian ◽  
Carlos Alberto Alves Cairo ◽  
Mario Lima de Alencastro Graça
Keyword(s):  
Carbon Fibers ◽  
High Performance ◽  
Thermal Protection ◽  
High Heat ◽  
Hollow Fibers ◽  
Thermal Protection Systems ◽  
Sic Fiber ◽  
Protection Systems ◽  
Transverse Thermal Conductivity ◽  
High Oxidation Resistance

SiCf/SiC composite has a high potential for applications such as thermal protection systems due to its high oxidation resistance, high heat emissivity and low through-the-thickness (transverse) thermal conductivity, mainly if hollow fibers are used as reinforcement phase of the composite. PAN polymer is a precursor widely used and studied for developing high performance carbon fibers. Most commercial carbon fibers are basically derived from PAN polymer. In this work, the influence of the fiber specific mass on the morphology of SiC fiber obtained by conversion reactions from PAN oxidized fiber precursor was investigated. These oxidized fibers were obtained by controlling the time and temperature during the process of stabilization/oxidation.

scholarly journals Transformation Thermodynamics with Arbitrarily Shaped Non-Conformal Objects and Coatings

2018 ◽  
Vol 186 ◽  
pp. 01007
Author(s):  
Qingxiang Ji ◽  
Guodong Fang ◽  
Jun Liang
Keyword(s):  
Thermal Protection ◽  
Small Region ◽  
Heat Fluxes ◽  
Temperature Fields ◽  
Heat Flows ◽  
Thermal Protection Systems ◽  
Thermal Fields ◽  
Design Flexibility ◽  
Protection Systems ◽  
Concentrate Heat

In this paper we apply transformation optics theory to thermodynamics and design thermal cloaks and concentrators with arbitrarily shaped non-conformal objects and coatings. Expressions of the required material parameters are derived analytically and then validated by numerical simulations. We apply this method to design a thermal cloak which can guide the heat flow around the inner domain without perturbation to external thermal fields. In this way, the object inside the inner domain is protected from the invasion of external heat fluxes. In contrast, a concentrator is designed to concentrate heat flows into a small region without disturbing outside temperature fields, which can considerably enhance the heat density in the designed domain. The proposed method extends the design flexibility in manipulating heat flux and will find wide applications in thermal protection systems, solar cells and so on.

scholarly journals Influence of the ambient temperature on the cooling efficiency of the high performance cooling device with thermosiphon effect

2018 ◽  
Vol 180 ◽  
pp. 02073
Author(s):  
Patrik Nemec ◽  
Milan Malcho
Keyword(s):  
Ambient Temperature ◽  
High Performance ◽  
Convection Heat Transfer ◽  
Heat Removal ◽  
Measuring Method ◽  
High Heat ◽  
Heat Fluxes ◽  
High Heat Flux ◽  
Cooling Efficiency ◽  
Cooling Device

This work deal with experimental measurement and calculation cooling efficiency of the cooling device working with a heat pipe technology. The referred device in the article is cooling device capable transfer high heat fluxes from electric elements to the surrounding. The work contain description, working principle and construction of cooling device. The main factor affected the dissipation of high heat flux from electronic elements through the cooling device to the surrounding is condenser construction, its capacity and option of heat removal. Experimental part describe the measuring method cooling efficiency of the cooling device depending on ambient temperature in range -20 to 40°C and at heat load of electronic components 750 W. Measured results are compared with results calculation based on physical phenomena of boiling, condensation and natural convection heat transfer.

scholarly journals Ablative Heating Technology in Hypersonic Re-entry Vehicles and Cruise Aircrafts

2019 ◽  
Vol 8 (3) ◽  
pp. 3007-3014
Keyword(s):  
Thermal Protection ◽  
Space Shuttle ◽  
High Heat ◽  
Heat Liberation ◽  
Cruise Missile ◽  
Thermal Protection Systems ◽  
Protection Systems ◽  
Heat Loads ◽  
Heating Technology ◽  
Multiple Strategy

The aim of researches conducted in thermal protection systems in aeronautics and astronautics field of engineering is to generally defend the craft from high heat loads during operation while operating at hypersonic regimes in air and space. The motive of the following composition is to draft a review analysis on ablative heating materials as thermal protective equipment on reusable planetary/atmospheric re-entry vehicles such as a space shuttle, an inter-continental ballistic missile, or a hypersonic cruise missile. The heat liberation can cause much damage to the aircraft/spacecraft whilst operation which is generally beyond repair. It is therefore of utmost importance to research multiple strategy to reduce the effect of shockwaves damage to spacecraft/aircraft materials. We shall initiate the analysis by mentioning some re-usable tile thermal protection system types such as high temperature reusable surface insulation tiles (H.R.S.I), fibrous refectory composite insulation tiles (F.R.C.I), low temperature reusable surface insulation tiles (L.R.S.I) and gradually move on to ablative thermal protection systems with the advent of reinforced carboncarbon’s application in astronautics and aeronautics respectively.

scholarly journals Optimal design of subcooled triangular microchannel heat sink exchangers with variable heat loads for high performance cooling

2021 ◽  
Vol 2116 (1) ◽  
pp. 012052
Author(s):  
David Olugbenga Ariyo ◽  
Tunde Bello-Ochende
Keyword(s):  
Heat Sink ◽  
High Performance ◽  
Flow Boiling ◽  
High Heat ◽  
Geometric Optimization ◽  
Heat Fluxes ◽  
Heat Sinks ◽  
Subcooled Flow Boiling ◽  
Subcooled Flow ◽  
Microchannel Heat Sinks

Abstract Deionized water at a temperature of 25 °C was used as the cooling fluid and aluminium as the heat sink material in the geometric optimization and parameter modelling of subcooled flow boiling in horizontal equilateral triangular microchannel heat sinks. The thermal resistances of the microchannels were minimized subject to fixed volume constraints of the heat sinks and microchannels. A computational fluid dynamics (CFD) ANSYS code used for both the simulations and the optimizations was validated by the available experimental data in the literature and the agreement was good. Fixed heat fluxes between 100 and 500 W/cm2 and velocities between 0.1 and 7.0 m/s were used in the study. Despite the relatively high heat fluxes in this study, the base temperatures of the optimal microchannel heat sinks were within the acceptable operating range for modern electronics. The pumping power requirements for the optimal microchannels are low, indicating that they can be used in the cooling of electronic devices.

Heat Transfer Characteristics of a Train of Droplets Impinging Over a Hot Surface: From Film Evaporation to Leidenfrost Point

2019 ◽  
Author(s):  
Ganesh Guggilla ◽  
Arvind Pattamatta ◽  
Ramesh Narayanaswamy
Keyword(s):  
Heat Transfer ◽  
High Performance ◽  
Heated Surface ◽  
Electronics Cooling ◽  
Spray Cooling ◽  
High Heat ◽  
Heat Fluxes ◽  
Air Cooling ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics

Abstract Due to the advancements in computing services such as machine learning and artificial intelligence, high-performance computing systems are needed. Consequently, the increase in electron chip density results in high heat fluxes and required sufficient thermal management to maintain the servers. In recent times, the liquid cooling techniques become prominent over air cooling as it has significant advantages. Spray cooling is one such efficient cooling process which can be implemented in electronics cooling. To enhance the knowledge of the process, detailed studies of fundamental mechanisms involved in spray cooling such as single droplet and multiple droplet interactions are required. The present work focuses on the study of a train of droplets impinging over a heated surface using FC-72 liquid. The surface temperature is chosen as a parameter, and the Dynamic Leidenfrost point (DLP) for the present impact conditions is identified. Spread hydrodynamics and heat transfer characteristics of these consecutively impinging droplets till the Leidenfrost temperature, are studied and compared.

Effect of Flow Guide Integration on the Thermal Performance of High Performance Liquid Cooled Immersion Server Modules

2015 ◽  
Author(s):  
Joshua Gess ◽  
Tyler Dreher ◽  
Sushil Bhavnani ◽  
Wayne Johnson
Keyword(s):  
Pressure Drop ◽  
Surface Temperature ◽  
Thermal Performance ◽  
Power Dissipation ◽  
High Performance ◽  
High Heat ◽  
Heat Fluxes ◽  
Dielectric Fluid ◽  
Computing Device ◽  
Flow Guide

Liquid immersion cooling technology, currently in its nascence as a commercially available solution for data center installations, is growing in popularity as the power density of next-gen electronics necessitates a matriculation to thermal management techniques capable of handling incredibly high heat fluxes reliably and efficiently. The use of boiling and single-phase convective solutions using dielectric fluids can result in dramatic reductions in chip temperatures, thus increasing reliability. The latter method is growing in popularity faster than the former but, as both of these approaches gain acceptance, packaging engineers will require insight into how coolant is distributed throughout the enclosure for either solution. More specifically, analytical and experimental techniques will be required to ascertain how thermal performance and system efficiency of more critical elements, such as processor chips, are affected by the auxiliary components, heated or not, that must exist within a computing device. These supplemental components, whether entirely passive or modestly heated, if placed strategically can be integrated in such a way to improve the thermal performance of the system by guiding the coolant through the liquid filled enclosure. To this end, flow guides, which simulate these auxiliary components, have been integrated into a small form factor high performance server module. The relationship between the surface temperature and the power dissipated by the primary heated elements within the device has been explored as well as the pressure drop experienced by the coolant flowing through the enclosure. Power dissipations near 450W have been achieved at a surface temperature of approximately 75°C with the use of flow guides, a near 50W improvement over previous results. Furthermore, this value was attained at a modest pressure drop of 0.71 psi for the dielectric fluid flowing through the cartridge. Slightly over 300W of power dissipation was achieved at an even lower pressure drop of 0.13 psi at a similar operating temperature. Pool boiling results have shown that passive elements can have a significant impact on thermal performance. Reductions of nearly 50W in the maximum power dissipation achieved have been shown when the largest flow guide is integrated. A PIV analytical method is proposed and applied to the current experimental facility to assess the effectiveness of the flow guide design proposed.

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