Session: 14-02: Brush/Labyrinth Seal

Paper Number: 151207

Algorithm Based Generation of Realistic Bristle Distribution: Comparison Between an Unstructured and a Structured Bristle Package for Brush Seal Simulation 

Reducing the leakage in aeroengines offers a high potential for efficiency improvements and fuel savings in air transport. Brush seals are able to significantly reduce leakage in comparison to the predominantly used labyrinth seals, but their application in gas turbines is restricted by the limited ability to predict their in-service behavior and leakage rates. This work contributes to enhancing brush seal simulations and improving their predictive accuracy. With the use of image processing algorithms, microscope images from a test stand are evaluated and individual bristles identified. A statistical analysis on these images determines the distribution of bristles in the bristle package. For pressure differences from 0 to 6 bar across the seal, representative unstructured bristle distributions can then be generated and used as input for CFD simulations. First, flow in one single bristle distribution is compared for different operating points. Further simulations compare the unstructured bristle package with a structured bristle setup. The comparison is conducted in 2D as well as 3D. Different types of 3D geometries are used to cover the fence height or the support ring, either with bristle-rotor contact or including a sealing gap between bristle tips and rotor surface. Simulations with an unstructured bristle package show good agreement with experimental findings. The comparison with a structured bristle package shows significant differences, proving the importance of simulating brush seals using a realistic bristle distribution.

Presenting Author: Moritz Ursprung Insitute for Test an Simulation for Gas Turbines, German Aerospace Center (DLR)

Presenting Author Biography: Studied mechanical engineering with focus on thermical turbomachinery in Karlsruhe.
Joined DLR in 2017, shortly after the institute was founded. During the first years worked on specification and development of test stands. Later took over the topic of simualtions regarding brush seals.

Authors:

Moritz Ursprung Insitute for Test an Simulation for Gas Turbines, German Aerospace Center (DLR)
Maksym Meyer Hochschule München University of Applied Sciences
Simon Hausruckinger Hochschule München University of Applied Sciences
Johann Göttler MTU Aero Engines AG
François Cottier MTU Aero Engines AG