Session: 25-04 Seals

Paper Number: 82235

82235 - Investigation of the Transient Closing Behavior of a Radially Adaptive Seal 

Due to an ever-increasing share of renewable production in the global energy market, the demand for flexible power generation is rising. Gas turbine power plants can efficiently fill this need by increasing their transient and partial load performance. New radial adaptive sealing concepts in the secondary air system have the potential to increase the partial load efficiency of turbomachinery and accelerate load ramps. These seals are pressure activated, adjusting to engine conditions in order to maintain a minimum gap width during the entire load cycle, defined as the seal’s operating gap width. The seal under investigation here is a hydrostatic advanced low-leakage (HALO) seal.

In this context a HALO seal was experimentally investigated in the rotating adaptive seals test rig at KIT, with a focus on the transient behavior of the seal closing to its’ operating gap width. For this measurement campaign, the pressure ratio, pressure difference, pressure ramp and swirl were varied over a series of test runs. Each test run consists of a controlled ramp up of pressure, a hold at maximum pressure, then a controlled ramp down of pressure. The dynamic movement of the seal shoe was measured via confocal and capacitive sensors, in addition to upstream and downstream pressures and the mass flows.

In this paper, the results of these experimental investigations are presented and analysed. These are first compared with previous investigations of HALO seals in the test rig at KIT to validate established relationships, including the influence of swirl, and highlight differences between seals. From these results, the relative influence of the pressure difference and the pressure ratio across the seal on the transient seal behavior is compared. Of particular interest is the effect of changing the pressure ramp gradient on the operating gap width. The results presented in this study give detailed insight into the transient movement of a HALO seal under various engine-similar influencing parameters. This is crucial to understanding how the seal behavior and performance will be affected when operating under different conditions and in different applications.

Presenting Author: James Lofts Institut für Thermische Strömungsmaschinen, Karlsruher Institut für Technologie

Presenting Author Biography: James Lofts is a PhD Student at the Institute of Thermal Turbomachinery at Karlsruhe Institute of Technology.<br/>James&#39; research focuses on adaptive sealing systems, specialising in rotating test rig development and seal modelling.

Authors:

James Lofts Institut für Thermische Strömungsmaschinen, Karlsruher Institut für Technologie
Corina Schwitzke Institut für Thermische Strömungsmaschinen, Karlsruher Institut für Technologie
Hans-Jörg Bauer Institut für Thermische Strömungsmaschinen, Karlsruher Institut für Technologie
Vincent Peltier Siemens Energy, Gas and Power
Kunyuan Zhou Siemens Energy, Gas and Power