Two heat-pipe test articles were fabricated and tested, furthering the development of a refractory-composite/heatpipe-cooled leading edge. A 3-ft-long, molybdenum-rhenium heat pipe with lithium working uid was fabricated and tested in a vacuum chamber at an operating temperature of 2460 ± F, verifying the heat-pipe design. Following the fabrication of the initial heat pipe, three additional heat pipes were fabricated and embedded in carbon/carbon. The carbon/carbon heat-pipe test article was successfully tested using quartz lamps in a vacuum chamber in both horizontal and vertical orientations. Startup and steady-state data indicated similar operation in both orientations but different behavior among the three heat pipes. Radiography and eddy current evaluations were performed on the test article and indicated differing carbon/carbon thicknesses and a potential disbond.Nomenclature d = artery diameter, in. m = mass of lithium in heat pipe, lb P = pressure, psi q = heat ux, Btu/s q 00 = heat ux per area, Btu/ft 2 -s r = radius, in. T = temperature, ± F t = time, s V = voltage, V x = distance from end of carbon/carbon, in.
A one-half-scale heat-pipe-cooled leading edge model was designed and fabricated to verify feasibility and performance of a full-scale Shuttle-type orbiter design. Model performance was investigated experimentally by radiant heating and aerothermal tests and analytically by using a simple technique which predicts heat pipe startup from the frozen state and also predicts transient and steady-state thermal behavior. Analytical results agree well with experimental results for startup and steady-state heat pipe operation. The results indicate that variations in angle of attack and roll orientation had a negligible effect on heat pipe performance. The heat pipes effectively isothermalized the leading edge, and reduced peak temperatures to levels compatible with the use temperatures of superalloys. Results of these tests demonstrated the durability of the heat-pipe-cooled leading edge in withstanding Earth-entry thermal and mechanical loads and indicate that the use of heat pipes in leading edge structures is a reliable concept for fully reusable hypersonic cruise and space transportation systems. a D So h I I T -M m P R Rn T r* 7 X Nomenclature speed of sound inside diameter of heat pipe gravitational constant latent heat of vaporization chordwise surface distance measured from nose total chordwise surface distance measured from nose to end of leading edge Mach number molecular mass of working fluid pressure heat flux sonic heat transport rate universal gas constant Reynolds number temperature temperature above which continuum flow conditions are assumed to exist in the vapor space time temperature difference angle of attack angle of roll ratio of specific heats mean free path viscosity density P = Subscripts c =combustor / = liquid max = maximum s = stagnation t = total v = vapor oo = free stream
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.