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

An improved understanding of the mechanisms of SC-CO2 jet drilling technology is important for the applicationof thisnew technology. The flow field structure and dynamic fluctuation ofSC-CO2 jets are the key factors affecting the jet erosionperformance. To improve the erosion performance of the SC-CO2 jet, it is necessary to study the relationship between the differentflow fields of the jet. In this study, a numerical simulation modelfor SC-CO2 jet drilling technology is established. Basedon the modified real-gas model, the pressure distribution and flowfield characteristics of the SC-CO2 jet were obtained bythe simulation investigation, and the reliability of the model wasverified. The results show that the flow field structure of a supercriticalCO(2) jet has typical compressible flow field characteristics.As the jet is fully expanded, its pressure fluctuation is slight andless affected by the distance between the nozzle and the wall. Whenthe jet is in the state of under-expansion, the flow field structurecharacteristics have a significant impact on the pressure distributionand peak pressure. At the same time, when the distance is large, whennozzle pressure ratio = 5, the pressure ratio has a more significantimpact on the flow field and the pressure peak and distribution. Thepressure distribution of different flow fields should be fully consideredin the application.