Large Eddy Simulations to Investigate the Fundamental Flow Physics of Supercritical Carbon Dioxide Turbulent Jets

Supercritical Carbon Dioxide is of interest in a wide range of engineering problems, including carbon capture, utilization, and storage as well as advanced cycles for power generation. Non-ideal variations in physical properties of supercritical Carbon Dioxide impact the physics of these systems. It is important to understand how drastic changes in thermodynamic properties influence these flow physics in order to aid in and optimize the design of future technologies related to carbon capture and sequestration. In this study, we simulate turbulent supercritical Carbon Dioxide jets to gain a better understanding of these physics. Of particular interest is the impact of pseudo-boiling on supercritical flow dynamics. We use a second order finite volume method with adaptive mesh refinement as implemented in the reacting flow solver, PeleC, to perform a Large Eddy Simulation of three turbulent jets of supercritical Carbon Dioxide. Additionally, we use the Soave-Redlich-Kwong equation of state to close the system and more accurately incorporate the departure from ideal gas behavior into the turbulent flow physics. We look at a variety of quantities of interest, including but not limited to axial velocity decay and spread, resolved Reynolds stress profiles at different down- stream locations, and resolved turbulent kinetic energy along the axial direction of the flow. Across the three cases, the only parameters that vary are the temperature and density of the ambient fluid. One case is isothermal, where the jet and ambient fluid temperature are the same, while the other two cases are non-isothermal, with one involving injection crossing over the pseudo-boiling point and one with injection moving away from the pseudo-boiling point. Results are contrasted with established theory for ideal gas jets and similar numerical studies involving transcritical injection in order to capture the effects of widely varying thermal properties in the pseudo-critical region. We found that the isothermal supercritical jet exhibits many similar flow characteristics compared to ideal gas round turbulent jets, with minor differences seen in the decay and spreading rate of the jet and in a noticeable anisotropy between resolved turbulent kinetic energy components. The non-isothermal jet excluding the pseudo-boiling point exhibits only small difference compared to the isothermal case. The non-isothermal case involving the pseudo-boiling point displays markedly different behavior, with evidence indicative of increased Kelvin-Helmholtz-like instabilities and much faster jet decay and disintegration. These factors impact the degree of mixing in the transition region of the jet, leading to finer-scale vortices and faster transition to ambient properties.