Session: 14-06 Compliant Seals

Paper Number: 127824

127824 - Modeling of Frictional Inter-Bristle Contact in Brush Seals With Shaft Radial Movements 

Brush seals can be deployed in turbines for the reduction in parasitic leakage flows to improve cycle thermal efficiency, and for load management within the engine. They have the potential to surpass labyrinth seals in sealing efficacy. However, their broad adoption is hindered by adverse effects such as pressure-stiffening and hysteresis which make their performance less predictable. The bristles bend upon shaft incursion and their subsequent response during shaft retraction is determined by the strength of the blowdown forces compared to frictional forces in the seal. Reduced seal compliance could lead to higher seal leakage or excessive contact forces and wear. In earlier research, the authors introduced and validated both analytical and numerical models for a single bristle, capturing the seal's reaction to shaft displacements under varied pressure conditions. This paper extends the numerical model to consider multiple bristles, accounting for inter-bristle contact and friction and allows the relative role of shaft friction, backing friction, and inter-bristle friction on the seal hysteresis to be determined. This enhanced model will be benchmarked against experimental findings from a pressurized seal. Preliminary outcomes indicate that inter-bristle friction significantly impacts the distribution of bristle tip loading, implying a significant influence on local wear. The study provides insight into how different geometrical and operational factors influence seal hysteresis.

Presenting Author: Harry Phan University of Surrey

Presenting Author Biography: Dr Harry Phan is a post-doctoral researcher in computational fluid dynamics and fluid structure interaction at the University of Surrey, working on the coupled flow, structural modelling and dynamic aspects of brush seals. He holds a PhD in Structural and Aerodynamic Mistuning Effects on Blade Aeroelasticity from the Oxford Thermofluids Institute.

Authors:

Harry Phan University of Surrey
Michael J Pekris University of Surrey
John Chew University of Surrey
Thomas Greenslade University of Surrey