Inlet preswirl dependence research on three different labyrinth seals

Abstract

In this paper, an angular velocity is proposed to calculate the air inlet preswirl condition. The potential influences on rotordynamic and leakage performance of inlet preswirl ratios ranging from −1–1 are considered in the traditional labyrinth seal (LS), diaphragm labyrinth seal (DLS) and hole diaphragm labyrinth seal (HDLS). The simulation results show that the inlet preswirl of the LS has little influence under low rotation speeds, while the negative influence on the higher rotation speed for the positive preswirl is clear. The maximum improvement of effective damping under the −1 preswirl ratio compared to zero preswirl conditions for LS, DLS and HDLS can reach 132.1%, 240.6% and 385.1%, respectively, when that of effective stiffness for DLS and HDLS can improve 14.8% and 90.1%, respectively, and that of leakage reduction for DLS and HDLS can reach 4.12% and 4.5%, respectively. Meanwhile, the average leakage under different conditions of HDLS can obtain 5.70% reduction than that of LS and 1.78% than DLS, which is better than another new seal, which was proposed by other scholars. Further discussions on detailed flow areas show that the existence of holes brings more energy dissipation for HDLS, which brings lower leakage among the three different seals. Comparing DLS and HDLS also shows a potential combination to obtain a new type of seal with higher stability for rotor-seal systems and lower leakage.