Experimental and numerical simulation study on the influence of structural factors on the leakage characteristics of clearance seals

Abstract

The leakage characteristics of clearance seals are affected by operating conditions, such as operating parameters and physical properties of the medium, and structural factors such as the clearance and surface structure of the seal. The reasonable design of the seal structure under different operating conditions is very important to ensure the excellent leakage resistance characteristics of the seal. Based on the self-developed plate test platform of the clearance seal, the leakage rate and outlet pressure under different seal clearance and static surface structure conditions have been obtained. The influence of structural factors such as the seal clearance values and its shape and the structure of the static surface on the leakage characteristics of the clearance seal is investigated. The influence mechanism of the structural factors on leakage characteristics of the seal is analyzed by the simulation of the three-dimensional flow field and the turbulent energy dissipation rate of the clearance seal. The results show that the leakage characteristics of the clearance seal are significantly affected by the seal clearance values and its shape, and the sealing surface structure on static and rotor. Under the same value of average seal clearance and compared to the parallel clearance seal, the seal with an axially inclined sealing clearance has better leakage control ability. However, the circumferentially inclined sealing clearance has little influence on leakage characteristics. The best choice of sealing surface structure under different seal clearance conditions is different. Among them, the smooth surface seal, the clearance seal with single-sided opening, and the clearance seal with double-sided holed are the optimal structures when the seal clearance is small (0.05–0.1 mm), moderate (0.3–0.4 mm), and large (0.8–1.0 mm) respectively. This phenomenon is the result of the combined effect of the direct air permeability effect in the sealing clearance, the vortex dissipation effect in the cavity, and the surface friction effect under different conditions.