CFD를 활용한 브러쉬 실의 회전체동특성 해석

Abstract

To improve the efficiency of steam turbines, this study examines the application of a brush seal with bristles having a minimum clearance in the rotor. To maximize the reduction of leakage, a hybrid seal was employed to replace one or two of the labyrinth teeth with bristles. In the design of the brush or hybrid seal, a dynamic coefficient prediction method was developed to evaluate vibration characteristics, in addition to the use of a leakage prediction method. In this paper, we propose a 3D computational fluid dynamics (CFD) analytical method based on dynamics analysis using the relative coordinate system, assuming that the bristle element is a porous medium and comparing the results with published experimental results. With the exception of K (direct stiffness), the dynamic characteristics of the brush seal with the bristles contacted with the rotor, k (cross coupled stiffness), C (damping), and c (cross coupled damping), were quite small and the vibration characteristics of the brush seal were relatively unaffected. Compared to the experimental results, 3D CFD analytical results of the hybrid seal revealed that K was 17.5% smaller, k was 3% larger, and C was 10% larger.