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Numerical study of supercritical and transcritical injection using different turbulent Prandlt numbers: A second law analysis

Abstract:

The purpose of this investigation is to study the supercritical and transcritical injection of cryogenic fluids by means of a Computational Fluid Dynamics analysis using a RANS approach and different turbulent Prandtl number models. Besides, with the aid of the differential equation for entropy, the local entropy generation is pursued. Using this method, the areas where the irreversibilities occur are detected, and the mechanisms concerning entropy generation identified. The novelty of the numerical procedure presented herein is the use of two different turbulent Prandtl number (PrT) models that affect strongly the result produced: a constant PrT and a molecular dependent PrT. The main results show that the constant PrT pbkp_redicts better the flow structure when compared to experimental data, being PrT = 0.5 the optimum one. This result suggest that supercritical and transcritical fluid injection are more dissipative processes than normal pressure injection, where PrT ≈ 1.