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Transpiration Cooling Using Porous Material for Hypersonic Applications
Published in Yasser Mahmoudi, Kamel Hooman, Kambiz Vafai, Convective Heat Transfer in Porous Media, 2019
Adriano Cerminara, Ralf Deiterding, Neil D. Sandham
In the transpiration cooling technique, instead, cooling is achieved by a cold fluid transpiring from a porous material. The cold fluid traversing the thickness of the porous material reduces the temperature of the interior porous walls and brings the absorbed heat content outside (a form of reverse heat flux similar to an ablative system). In this case, the coolant injection into the boundary layer is not localized but distributed over the surface, and irregular due to the interior structure of the porous material. For the flow through porous media at very low Reynolds numbers (lower than 1), the flow rate per unit mass and area coming out from the surface (named also specific discharge or superficial velocity) is linked to the pressure gradient within the porous layer, the fluid viscosity, and the permeability of the material from the Darcy law: () v=−KDμ∂p∂x,
Effect of transpiration on friction, heat, and mass transfer
Published in S. Mostafa Ghiaasiaan, Convective Heat and Mass Transfer, 2018
Transpiration cooling is a common and effective method of active cooling of a typically large surface that is exposed to a thermal load that includes a significant convective component. Figure 8.3 is a schematic of a surface that is cooled by transpiration. During transpiration cooling, a coolant passes through the heated wall and not only absorbs some of the internal energy in the solid structure, but also reduces the convective heat flux at the surface. The flow through the wall is commonly achieved by making the structure porous or perforated. Transpiration cooling by an inert gas or liquid can also prevent the oxidation of the heated surface by hot air. Among advantages of transpiration cooling is the simplicity of controlling the surface temperature by adjusting the transpiration coolant flow rate. Examples of application include combustion chambers of rocket engines and the surfaces of hypersonic aircraft, to name a few.
Unsteady three dimensional bioconvective flow of Maxwell nanofluid over an exponentially stretching sheet with variable thermal conductivity and chemical reaction
Published in International Journal of Ambient Energy, 2022
Shafiq Ahmad, Muhammad Naveed Khan, Sohail Nadeem
The heat exchange for single or many algebraic substances with linear convective conditions is described by the convective boundary condition of liquid flow. It is used in a variety of processes, including material drying, transpiration cooling, thermal energy storage, nuclear power plants, and gas turbines. As a result, it is reasonable to investigate the convective boundary condition. Anuar et al. (2021) investigate the steady flow and heat transfer through a moving wedge in Al2O3-Cu/water nanofluid with convective boundary condition, suction parameter, and Biot number parameter. Yao, Fang, and Zhong (2011) established that a stretching sheet can transfer heat from a viscous fluid along with convective boundary condition. The influence of variable molecular diffusivity, nonlinear thermal radiation, convective boundary conditions, and variable molecular diffusivity on Prandtl fluid passing through a stretching sheet is described by Sajid et al. (2021). (Nadeem, Haq, and Akbar 2014; Nadeem, Mehmood, and Akbar 2014) demonstrated the MHD flow of a Casson nanofluid with the convective boundary condition.
Heat Flux Determination from Pressure Data for a Transpiration Cooling Environment
Published in Heat Transfer Engineering, 2023
Fabian Hufgard, Stefan Loehle, Stefanos Fasoulas
Transpiration cooling is an active cooling technique, which promises to widen the range of hypersonic flight applications where extreme thermal conditions prevent the usage of passively cooled structures [1–6]. Transpiration cooling means that a fluid is fed through a porous wall and exits into the hot gas region. This has two favorable effects. Firstly, the fluid picks up some heat from the hot wall and carries it out of the system, thus it actively cools the wall. Secondly, the fluid mixes into the boundary layer, which reduces the temperature in the boundary layer. Consequently, convective heat transfer into the wall is reduced. A detailed description of this process can be found in Böhrk et al. [3] and references therein.
Comparative appraisal of nanofluid flows in a vertical channel with constant wall temperatures: an application to the rocket engine nozzle
Published in Waves in Random and Complex Media, 2022
Muhammad Ramzan, Nazia Shahmir, Hassan Ali S. Ghazwani, M. Y. Malik
Future space systems aim to boost rocket thrust, enrichment in their operating life, and augmentation in their reliability and reusability. This necessitates optimal cooling, either to prevent failure or to lengthen the life cycle of the burnt chamber material within tolerable temperature limits. Regenerative cooling is the documented standard for long-running liquid-fueled rocket nozzles [1]. This cooling also identified as forced convection cooling, is the process of passing cold fuel at high speeds through minuscule channels embedded in the nozzle walls to absorb the heat from the hot wall and warm the fuel before it is released. The study [2] demonstrated that transpiration cooling is a superior technique for liquid-fueled rocket engine nozzles that operate for extended periods. During transpiration cooling, coolant passes through the penetrable wall and creates a film layer on the surface that helps to prevent heat transfer from the hot mainstream. Nowadays, transpiration cooling is being used in the aircraft's engine combustion chamber and rockets’ nozzle. There have been several experimental and numerical investigations on transpiration cooling accessible in the literature. Ming et al. [3] numerically studied the steady two-dimensional mixed convection flow evaporation of liquid across a vertical wall in spongy media. It is found in this study that the solution was non-identical for varied profile configurations. Jiang et al. [4] experimentally studied the turbulent flow and heat transmission in a channel in a comparative study focusing on with and without transpiration cooling. The squeezing MHD dusty liquid flow with particle suspension in a rotating channel with transpiration cooling is scrutinized by Mahanthesh et al. [5]. Goyal and Bhargava [6] examined the (Element free Galerkin method) simulation of transpiration cooling in nanoliquid filled (wavy) channel. Dahmen et al. [7] investigated the use of spongy media to cool rocket thrust chambers by transpiration cooling. Experimentally, Huang et al. [8] scrutinized the phenomenon of transpiration cooling to protect greater heat flux channel walls of spaceflight vehicles. The effectiveness of transpiration cooling is shown to improve as the coolant injection ratio is raised. Additionally, authors [9–14] highlighted different flow geometries that include the effect of transpiration cooling.