Tracking of Bristle Tip Deflections to Demonstrate Blow-Down in Brush Seals
Year: 2024
Type: article
Abstract: Sealing in gas turbines is paramount to overall performance and efficiency. Brush seals offer superior performance compared to other sealing solutions commonplace in modern turbomachinery. When subjected to a pressure load, a ring of flexible fine wire bristles—fitted at a lay angle to the radial plane—compact to resist the oncoming flow and deflect towards the rotor in a process known as blow-down. This study employs Digital Image Correlation (DIC) to track individual bristle tips in three spatial axes throughout a large-scale brush seal test facility. This is the first-time direct measurements of blow-down throughout the bristle pack have been presented, providing a unique insight into the mechanical behavior of brush seals. Increased magnitudes of blow-down and axial bristle deflection were demonstrated in upstream bristle rows and at larger clearances. Analysis of these results in conjunction with the interrogation of the inter-bristle pressure field proved that blow-down is more prevalent for pressure relieving (PR) brush seals in comparison to conventional configurations. The reduction in the through-flow clearance area resulted in a significant enhancement in sealing performance for a clearance seal, highlighting a key advantage of the pressure relieving back plate design.
DOI: 10.1115/1.4066608
Institution: University of Bath
Language: English
Subfield: Aerospace Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
OpenAlex ID: W4402859519