Numerical study on the cooling performance and inlet mass flow rate per unit area of Ranque-Hilsch vortex tubes with different area ratios

The development of the Ranque-Hilsch vortex tube has stagnated since the 1950s, when Hilsch improved the vortex tube proposed by Ranque. Consequently, the performance of vortex tubes has remained constant for the past 70 years. In addition to the unclear flow structure and energy separation mechanism of vortex tubes, the lack of a mature design method for vortex tubes has also limited its widespread adoption for industrial applications. The inlet nozzle and main tube parameters have been studied extensively, and matching the inlet with the main tube is considered an important step in the design of a vortex tube; however, this process has not been studied extensively. In addition, although the temperature drop at the cold exit is a commonly adopted performance benchmark, it is not possible to establish a close relationship between this parameter and the geometric parameters of a vortex tube. This study investigates the relationship between the cooling performance and the area ratio of a vortex tube. The results indicate that the inlet mass flowrate per unit area has a positive correlation with the cooling performance, and its influence on the performance of a vortex tube is higher than that of the distribution of the reverse flow boundary. Therefore, the inlet mass flowrate per unit area can potentially be a geometric performance benchmark. However, further studies are required to develop better guidelines for optimizing the design and to obtain a deeper understanding of the energy separation mechanism of vortex tubes.