Experimental Investigation of Liquid Methane Convection and Boiling in Rocket Engine Cooling Channels

Abstract

The steady state heat transfer characteristics under internal forced convection of liquid methane were experimentally investigated using a rectangular channel with a cross section of 1.8 mm x 4.1 mm and square channels with a cross section of 3.2 mm x 3.2 mm; three square channels had surface finishes typical of milled channels and another three square channels had internal longitudinal fins. A High Heat Flux Test Facility (HHFTF) capable of handling cryogenic temperatures that was developed at the Center for Space Exploration Technology Research (cSETR) for the purpose of simulating the high heat load conditions representative of regeneratively cooled rocket engines was used in this study. For the rectangular channel, Reynolds numbers ranged between 68,000 and 131,000, while the Nusselt numbers were between 40 and 325. For the rough channels, Reynolds numbers ranged from 82,000 to 131,000, and Nusselt numbers were between 65 and 810. The longitudinally finned channels had Reynolds numbers ranging from 50,000 to 128,000, and Nusselt numbers between 70 and 510. Sub-cooled film-boiling phenomena were discovered for all the channels presented in this study. Film-boiling onset at Critical Heat Flux (CHF) was correlated to the Boiling Number, Bo ~0.1. Convective Nusselt number follows predicted trends for Reynolds number with a wall temperature correction for both the boiling and non-boiling regimes. NomenclatureA w = Test section coolant channel wall surface area, m 2 A c = Test section coolant channel cross-sectional area, m 2 Bo = Boiling number C p = Isobaric heat capacity, kJ/kg-K D hyd = Hydraulic diameter, m h = Convection coefficient, kW/m 2 -K i fg = Fluid heat of vaporization, kJ/kg k = Fluid conduction coefficient, W/m-K ̇ = Mass flow rate, kg/s Nu D = Nusselt number based on hydraulic diameter P avg = Fluid test article average pressure, MPa 2 P in = Fluid test article inlet pressure, MPa P out = Fluid test article outlet pressure, MPa Q = Total heat transfer, kW q" = Heat flux, kW/m 2 R a = Arithmetic mean value scale, microns Re = Reynolds number T b = Average fluid bulk temperature, K T in = Fluid test article inlet temperature, K T out = Fluid test article outlet temperature, K T sat = Fluid saturation temperature, K T w = Wall temperature, K v = Fluid bulk velocity, m/s x = Fluid quality, x < 0 for sub-cooling z crit = Critical length of tube to reach critical heat flux, m ΔT = Fluid inlet/outlet temperature difference, K  = Fluid viscosity, Pa-s  = Fluid density, kg/m 3

Effect of Aspect Ratio on Supercritical Heat Transfer of Cryogenic Methane in Rocket Engine Cooling Channels

“…Their studies indicate that the thermal conductivity of the wall material has a significant effect on conjugate heat transfer due to heat flux redistribution in the solid region. Trejo et al (2013Trejo et al ( , 2014) experimentally investigated the heat transfer characteristics of liquid methane flowing in channels of square and rectangular cross sections and the results are in good agreement with NASA/Rocket dyne Nusselt number correlation. Hungfang et al(2013) experimentally investigated heat transfer of supercritical cryogenic methane in a miniature tube.…”

Heat Transfer Deterioration Effects of Cryogenic Methane in Rocket Engine Cooling Channels

“…The study on rectangular channels was extended by Wang et al (2013) considering the thickness of the wall and the reported that the thermal conductivity of the wall has significant effect on the conjugate heat transfer due to heat flux redistribution in the solid region. Trejo et al (2013Trejo et al ( , 2014 experimentally investigated the heat transfer characteristics of liquid methane flowing in channels of square and rectangular cross sections and their results are in good agreement with that obtained from NASA/Rocket dyne Nusselt number correlation. Gu et al (2013) experimentally investigated heat transfer characteristics of supercritical cryogenic methane in a miniature tube and developed a semi-empirical correlation.…”

Thermal Behaviour of the Cooling Jacket Belonging to a Liquid Oxygen/Liquid Methane Rocket Engine Demonstrator in the Operation Box

“…The investigation on LRE sub-components and sub-systems, such as injectors, injector heads, and cooling jackets, in particular, still represents a very important activity in the development of engines in the near future and is conducted by means of a strict link between experimental and numerical methods [11]. The detailed analyses of the physics involved are aimed at setting up more reliable design tools and numerical methods, as well as developing new approaches [12,13].…”