Jet disintegration in supercritical environments

Abstract

A N2 jet was injected into quiescent ambient N2. The jet temperature was measured by four T-type thermocouples: one inside the injector and three at downstream positions (0.9d, 10.6d, and 28.1d, respectively; here, d is the inner diameter of the jet). The density was also measured downstream to 15d using two-dimensional Raman scattering with a pulse stretcher. Normally, our observations were consistent with expectations according to classical mixing theory; however, within a certain injection temperature range, there was no constant density region inside the jet core, and the jet temperature was measured to decrease. To explain this behavior of the jet, we considered three effects: classical mixing, thermal disintegration, and relaxation from high to low pressures. The absence of jet potential core can be explained by both thermal disintegration and relaxation, while the decrease of the temperature could be explained only by relaxation.