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CRYOGENIC FLUID JET DYNAMICS AT SUPERCRITICAL CONDITIONS

Nan Zong
Department of Mechanical & Nuclear Engineering The Pennsylvania State University University Park, PA 16802, USA

Shanwu Wang
Department of Mechanical and Nuclear Engineering The Pennsylvania State University University Park, PA 16802, USA

Vigor Yang
Department of Mechanical Engineering The Pennsylvania State University University Park, PA 16802, USA; School of Aerospace Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA

Resumo

Injection of cryogenic fluid initially at a subcritical temperature into a supercritical environment has been investigated numerically. The model accommodates full conservation laws and real-fluid thermodynamics and transport phenomena. All of the thermophysical properties are determined directly from fundamental thermodynamic theories and the corresponding state principles. The resultant scheme is valid for the entire fluid states of concern. Turbulence closure is achieved using a large-eddy-simulation technique. As a specific example, the dynamics of a liquid nitrogen stream injected into a supercritical nitrogen environment has been studied systematically over a broad range of ambient pressure. Owing to the large property variations from the injected and surrounding fluids, a string of strong density-gradient regimes is generated around the jet surface and exerts a stabilizing effect on the flow evolution. The situation becomes more evident with decreasing pressure. The kinetic energy of the surface motion is transferred from its vertical to the horizontal component; the instability waves are effectively suppressed. The jet dynamics is largely dictated by the local thermodynamic state. When the fluid temperature transits from the sub- to the super-critical value, the rapid property variations may qualitatively change the jet behavior compared with its counterpart at low pressures.