Numerical Study on a New Tesla Valve Structure Dry Gas Seal

Research into the design of dry gas seal face groove patterns has been a hot issue in this field, and efficient dynamic pressure groove patterns are essential for the stable operation of dry gas seals. This paper proposed a new (Tesla valve type) dry gas sealing groove structure with more gathering points and a larger high pressure area based on the single-guide characteristics of the Tesla valve structure, and found through systematic research that this groove can obtain better sealing results than the classical logarithmic spiral groove.　Based on the backflow blockage effect of the Tesla valve structure, and with reference to the winged barrier geometry of the Tesla valve structure, a geometric and mathematical model of the Tesla valve seal groove type was developed. On the basis of the mesh-independent analysis, a systematic numerical simulation of the seal performance with different geometrical and operating parameters was carried out using Fluent software to obtain the steady's steady-state performance parameters, such as seal opening force, air film stiffness, leakage rate and the variance of transient film pressure fluctuation amplitude. The results showed that the maximum opening force of the Tesla valve groove type was slightly less than that of the classical logarithmic spiral groove under the same operating conditions, but the Tesla valve groove type had more than one high pressure area point and the high pressure area was significantly larger than that of the classical logarithmic spiral groove. Compared to the classic logarithmic spiral groove, the Tesla valve groove type had better opening force and stiffness characteristics under the same operating conditions, especially at high rotational speed, high pressures and small film thicknesses with large groove depths. The main valve channel width B_m, the branch valve channel width B_t and the valve groove radius R_v had a large impact on the opening force and leakage rate of the Tesla valve groove type, taking into account the opening force and leakage rate, the best choice of the three intervals were: B_m=4~6 mm, B_t=1.7~2.1 mm, R_v=22.5~32.5 mm. The Tesla valve groove type had almost 20% higher stiffness than the spiral groove in the stable operating range of the dry gas seal gas film (h=3~6 μm), and at high rotational speed (N>30000 r/min), the Tesla valve groove type was more stable and has smaller pressure fluctuations. Finally, based on the Taguchi design and multi-parameter systematic analysis with Minitab software, it was concluded that the order of influence of each factor on the sealing opening force was medium pressure>film thickness>groove depth>rotational speed>branch valve channel>main valve channel. The order of influence of each factor on the sealing leakage rate was medium pressure>film thickness>rotational speed>groove depth>main valve channel>branch valve channel. The main difference was the different weights of film thickness, rotational speed, main valve channel and branch valve channel.