Simulation Investigation on the Structure and Its Influence on the Impinging Pressure of the Carbon Dioxide Jet.

Abstract

An improved understanding of the mechanisms of SC-CO2 jet drilling technology is important for the application of this new technology. The flow field structure and dynamic fluctuation of SC-CO2 jets are the key factors affecting the jet erosion performance. To improve the erosion performance of the SC-CO2 jet, it is necessary to study the relationship between the different flow fields of the jet. In this study, a numerical simulation model for SC-CO2 jet drilling technology is established. Based on the modified real-gas model, the pressure distribution and flow field characteristics of the SC-CO2 jet were obtained by the simulation investigation, and the reliability of the model was verified. The results show that the flow field structure of a supercritical CO2 jet has typical compressible flow field characteristics. As the jet is fully expanded, its pressure fluctuation is slight and less affected by the distance between the nozzle and the wall. When the jet is in the state of under-expansion, the flow field structure characteristics have a significant impact on the pressure distribution and peak pressure. At the same time, when the distance is large, when nozzle pressure ratio = 5, the pressure ratio has a more significant impact on the flow field and the pressure peak and distribution. The pressure distribution of different flow fields should be fully considered in the application.