Experimentelle und numerische Untersuchungen zum Durchflußverhalten von Labyrinthdichtungen von Turbomaschinen unter dem Einfluß von Rotation, Wellendesaxierung und Drall der Zuströmung

Abstract

Investigations on the mass flow through straight-through and staggered labyrinth seals are presented. Special attention is given to the influence of the pressure ratio, the gap with, the eccentricity of the rotor (parallel as well as angular displacement of the axis), to the rotation of the rotor and to an entry swirl (co- and counterrotating to the rotor) on the leakage of the labyrinth seals. The newly developed test facility, which allows the investigation of three-dimensional effects, is presented. The geometric dimensions of the investigated labyrinth seals fit the geometric dimensions of labyrinth seals of running machines. The data derived from extensive measurements are discussed and presented in detail. Using a commercial CFD-code based on the finite-elements method, the discharge coefficients of the investigated labyrinth seals in the case of a stationary rotor without any eccentricity are computed. The steady state, rotationally-symmetric compressible turbulent flow is calculated using the finite-elements method. In order to generate a mesh, structured and unstructured grids are combined. The description of the turbulent flow is based on the standard k-#epsilon#-model. There is good agreement (+ 5 to 8 %) between calculated and measured values in case of the straight through seal with the smallest gap width and for all staggered labyrinth seals. The numeric simulations of the straight through labyrinth seals with a noticeable carry-over effect show a deviation of about + 20 %.