Temperature measurement of cryogenic nitrogen jets at supercritical pressure

Abstract

The temperatures of transcritical and supercritical nitrogen jets were measured to explore the in §uence of ¤pseudovaporization¥ upon cryogenic propellant mixing in high-pressure rocket chambers. Pseudovaporization is the large thermodynamic transition near the pseudocritical temperature under transcritical conditions, which can include a drastic density change and large peak of isobaric speci¦c heat. A decline in the rise of temperature along the jet centerline of the transcritical jet was caused at the position where the local temperature reached nearpseudocritical temperature. This can be considered to be due to the large peak of isobaric speci¦c heat. The density jump appeared near the pseudocritical temperature, which can be correlated to the sudden expansion due to pseudovaporization. The axial pro¦les of the temperature and density of the supercritical jet monotonically increased and decreased, respectively, in the downstream region of the end of the jet potential core. Similar to the axial pro¦les, the radial pro¦les of the temperature were in §uenced by the pseudovaporization ¡ i. e., the temperature rise in the radial direction became very shallow in the region where the local temperature was still lower than the pseudocritical temperature. The full width at half maximum of the density pro¦les stayed almost constant further downstream of the end of the jet potential core, whereas that of the mass fraction pro¦les of the incompressible variable-density jet began to increase near the end of the potential core. Hence, the evolutions of jet mixing layers of transcritical jets and variable-density jets can be considered to di¨er due to pseudovaporization. NOMENCLATURE SymbolsD inner diameter of injector, 2 mm h speci¦c enthalpy