Advanced Labyrinth Seal Design Performance for High Pressure Ratio Gas Turbines

Abstract

Labyrinth seal air leakage performance in current and advanced high pressure ratio gas turbines is directly related to the limitations of current available sealing technology. Sea design technology has not kept pace with the gas turbine major component advances. Therefore, an investigation was undertaken to design, fabricate and test several unique labyrinth seal concepts intended to decrease leakage through higher efficiency. The approach used in the unique designs for improving the efficiency of labyrinth seals involved increasing the internal cavity turbulence of the seal. The program involved three test and evaluation phases: (a) water tunnel studies; (b) static air rig tests; and (c) dynamic air rig tests. The water tunnel rig provided an economical method of screening the unique candidate designs. The most promising configurations from the water rig were fabricated and tested in the static air rig. Those configurations demonstrating a significant reduction in seal leakage over current designs were tested dynamically up to 786 ft/sec in an air rig to assess the effects of rotation. The results of this program effort show that each of the unique seal designs achieved lower leakage rates than a standard baseline step seal. In addition the dynamic seal test results show minimal effect on leakage due to rotation up to 786 ft/sec.