Numerical Analysis of Convection / Transpiration Cooling

Abstract

An innovative concept utilizing the natural porosity of refractory-composite materials and hydrogen coolant to provide CONvective and TRANspiration (CONTRAN) cooling and oxidation protection has been numerically studied for surfaces exposed to a high heat flux, high temperature environment such as hypersonic vehicle engine c0mbustor walls. A boundary layer codc and a porous media finite difference code were utilized to analyze the effect of convection and transpiration cooling on surface heat flux and temperature.The boundary layer code determined that transpiration flow is able to provide blocking of the surface heat flux only if it is above a minimum level due to heat addition from combustion of the hydrogen transpirant.The porous media analysis indicated that cooling of the surface is attained with coolant flow rates that are in the same range as those required for blocking, indicating that a coupled analysis would be beneficial.

Transpiration-Cooled Hypersonic Flight Experiment: Setup, Flight Measurement, and Reconstruction

“…Radiation within the porous structure is neglected. According to Glass, the balance for the wall material is [5] …”

“…The volumetric heat transfer coefficient α V is determined by the Nusselt correlation [18] α V Nuλ c ∕k D aRe b λ∕k D (18) with coefficients a and b from Florio et al [18] and the Reynolds number of the coolant in the pores, neglecting turbulence, [5] Re ρ F k 1.5…”

“…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 is introduced, here, serving to solve the heat balances of the vehicle structure [6].…”

Thermal ablation resistance of melt-infiltrated titanium diboride-(copper, nickel) composites

“…Self-transpiration cooling technique applied for components of solid rocket motor (working temperature near to 3000 • C) and thermal protection systems (TPS) can be realized and executed through the material design and preparation of IPCs [11][12][13]. Particularly ceramic-metal IPCs contain high melting point ceramic phase (such as TiB 2 , TiC, ZrB 2 , HfB 2 , etc.)…”

Aerothermal–Structural Analysis of a Rocket-Launched Mach 8 Scramjet Experiment: Ascent

“…Thermal surface effects are especially important for air-breathing hypersonic vehicles that, for drag-reducing purposes, are slender vehicles often with sharp leading edges: a configuration leading to both high thermal loads and consequently high thermally induced stresses [1]. A number of methods to mitigate thermal loads and stresses on hypersonic vehicles exist, the most common of which are the use of exotic materials for thermal protection such as those on NASA's X34 [2] and Space Shuttle [3] vehicles and active cooling technologies [4][5][6]. Incorporating these, however, often comes at significant economic and packaging expense, and thus a third mechanism of passive cooling is becoming a more popular method of thermal management on hypersonic flight-test vehicles [7][8][9].…”