A new metal cloth stationary seal for gas turbine applications

Abstract

There are numerous opportunities for advanced seals in modern gas turbines; the need for better seals is driven by higher efficiency demands. In this work a systematic way of utilizing metal cloth as a stationary seal is presented. The primary advantage of the cloth seal over the current rigid seals is to provide flexibility in the junctions between turbine components and to minimize the wear and leakage by accommodating mismatches between the components. A number of steps has been taken in the development of a metal cloth seal. 1) The effect of cloth weave orientation on sealing has been investigated. The effect of the cloth weave and wire orientation on wear rates has been studied. The type of weave has a strong effect on wear rates and leakage characteristics of the metal cloth. 2) Several superalloy wires in cloth form have been wear tested against gas turbine materials; this has been followed by oxidation/corrosion tests. 3) The formability of the metal cloth was studied. Several designs have been developed for various locations of the engine. The design and results of a particular application will be presented in this paper. Prototype seals were made and tested for the combustor exit location. Previously, stationary brush seals were developed and tested for this location; these reduced leakage by a factor of three and wear by a factor of ten compared to the current static seals. In this iteration, the metal cloth seal used at the same location showed approximately the same improvement a brush seal, with significantly reduced cost.