Effects of operating damage of labyrinth seal on seal leakage and wheelspace hot gas ingress

摘要

The labyrinth seal is widely used in turbomachinery to minimize or controlleakage between areas of different pressure. The present investigation numericallyexplored the effect of damage and wear of the labyrinth seal on the turbomachineryflow and temperature fields. Specifically, this work investigated: (1) the effect of rubgroovedownstream wall angle on seal leakage, (2) the effect of tooth bending damageon the leakage, (3) the effect of tooth "????????mushrooming"???????? damage on seal leakage, and (4)the effect of rub-groove axial position and wall angle on gas turbine ingress heating.To facilitate grid generation, an unstructured grid generator named OpenCFD wasalso developed. The grid generator is written in C++ and generates hybrid gridsconsisting primarily of Cartesian cells.This investigation of labyrinth seal damage and wear was conducted using theReynolds averaged Navier-Stokes equations (RANS) to simulate the flows. The high-Reynolds k - Model and the standard wall function were used to model the turbulence.STAR-CD was used to solve the equations, and the grids were generated usingthe new code OpenCFD.It was found that the damage and wear of the labyrinth seal have a significanteffect on the leakage and temperature field, as well as on the flow pattern. Theleakage increases significantly faster than the operating clearance increase from thewear. Further, the specific seal configuration resulting from the damage and wear was found to be important. For example, for pure-bending cases, it was found that thebending curvature and the percentage of tooth length that is bent are important, andthat the mushroom radius and tooth bending are important for the mushroomingdamage cases. When an abradable labyrinth seal was applied to a very large gasturbine wheelspace cavity, it was found that the rub-groove axial position, and toa smaller degree, rub-groove wall angle, alter the magnitude and distribution of thefluid temperature.