Next Article in Journal
Uncertainty Management at the Airport Transit View
Next Article in Special Issue
Continued Experimental Study on the Friction Contact between a Labyrinth Seal Fin and a Honeycomb Stator: Slanted Position
Previous Article in Journal
The Random Walk of Cars and Their Collision Probabilities with Planets
Previous Article in Special Issue
Prediction of Heat Transfer in a Jet Cooled Aircraft Engine Compressor Cone Based on Statistical Methods
Article Menu
Issue 2 (June) cover image

Export Article

Open AccessArticle
Aerospace 2018, 5(2), 58; https://doi.org/10.3390/aerospace5020058

Effects of the Back Plate Inner Diameter on the Frictional Heat Input and General Performance of Brush Seals

1
Institute of Thermal Turbomachinery (ITS), Karlsruhe Institute of Technology, Kaiserstraße 12, 76131 Karlsruhe, Germany
2
Institute of Jet Propulsion and Turbomachinery, Technical University Braunschweig, Hermann-Blenk-Str. 37, 38108 Braunschweig, Germany
These authors contributed equally to this work.
*
Author to whom correspondence should be addressed.
Received: 19 April 2018 / Revised: 22 May 2018 / Accepted: 24 May 2018 / Published: 25 May 2018
(This article belongs to the Special Issue Secondary Air Systems in Gas Turbine Engines)
Full-Text   |   PDF [16452 KB, uploaded 29 May 2018]   |  

Abstract

Reducing losses in the secondary air system of gas and steam turbines can significantly increase the efficiency of such machines. Meanwhile, brush seals are a widely used alternative to labyrinth seals. Their most valuable advantage over other sealing concepts is the very small gap between the sealing package and the rotor and thus reduced leakage mass flow. This small gap can be achieved due to the great radial flexibility without running the risk of severe detrimental deterioration in case of rubbing. Rubbing between rotor and seal during operation might occur as a result of e.g., an unequal thermal expansion of the rotor and stator or a rotor elongation due to centrifugal forces or manoeuvre forces. Thanks to the flexible structure of the brush seal, the contact forces during a rubbing event are reduced; however, the frictional heat input can still be considerable. Particularly in aircraft engines with their thin and lightweight rotor structures, the permissible material stresses can easily be exceeded by an increased heat input and thus harm the engine’s integrity. The geometry of the seal has a decisive influence on the resulting contact forces and consequently the heat input. This paper is a contribution to further understand the influence of the geometrical parameters of the brush seal on the heat input and the leakage during the rubbing of the seal on the rotor. In this paper, a total of three seals with varied back plate inner diameter are examined in more detail. The experimental tests were carried out on the brush seal test rig of the Institute of Thermal Turbomachinery (ITS) under machine-relevant conditions. These are represented by pressure differences of 1 to 7 bar, surface speeds of 30 to 180 m/s and radial interferences of 0.1 to 0.4 mm. For a better interpretation, the results were compared with those obtained at the static test rig of the Institute of Jet Propulsion and Turbomachinery (IFAS) at the Technical University of Braunschweig. The stiffness, the blow-down and the axial behaviour of the seals as a function of the differential pressure can be examined at this test rig. It could be shown that the back plate inner diameter has a decisive influence on the overall operating behaviour of a brush seal. View Full-Text
Keywords: brush seal; frictional heat input; fence height; stiffness; blow-down; rubbing brush seal; frictional heat input; fence height; stiffness; blow-down; rubbing
Figures

Graphical abstract

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
SciFeed

Share & Cite This Article

MDPI and ACS Style

Hildebrandt, M.; Schwarz, H.; Schwitzke, C.; Bauer, H.-J.; Friedrichs, J. Effects of the Back Plate Inner Diameter on the Frictional Heat Input and General Performance of Brush Seals. Aerospace 2018, 5, 58.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics

1

Comments

[Return to top]
Aerospace EISSN 2226-4310 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top