@inproceedings{HelmSpliethoffNeef2007, author = {Helm, Peter and Spliethoff, Hartmut and Neef, Matthias}, title = {Closing the Gap: Measuring Bristle Blow Down of Brush Seals}, series = {19 th International Conference on Fluid Sealing, Poitiers}, booktitle = {19 th International Conference on Fluid Sealing, Poitiers}, address = {Poitiers}, year = {2007}, language = {en} } @inproceedings{HelmPugachevNeef2008, author = {Helm, Peter and Pugachev, Alexander and Neef, Matthias}, title = {Breaking the Swirl With Brush Seals: Numerical Modeling and Experimental Evidence}, series = {Proceedings of the ASME Turbo Expo 2008 : presented at the 2008 ASME Turbo Expo, June 9 - 13, 2008, Berlin, Germany}, volume = {4}, booktitle = {Proceedings of the ASME Turbo Expo 2008 : presented at the 2008 ASME Turbo Expo, June 9 - 13, 2008, Berlin, Germany}, publisher = {ASME}, address = {New York}, organization = {American Society of Mechanical Engineers Corporation; International Gas Turbine Institute Corporation}, isbn = {978-0-7918-4314-7}, doi = {10.1115/GT2008-50257}, pages = {1387 -- 1396}, year = {2008}, abstract = {Striving for smaller losses in turbomachinery has led to many advancements in the design of seals. Modern sealing concepts such as brush seals hold a great potential to increase the efficiency of both flight engines and stationary turbines. At the same time, in order to maintain stable operating conditions of the rotor, swirl-induced forces must be kept at a minimum in the sealing channels. Therefore, the influence of the permeable and flexible bristle pack of brush seals on the flow around the rotor surface must be known. In this paper the swirl flow in the cavities of two different seal geometries is studied experimentally and numerically. A conventional three-tooth labyrinth serves as a reference. A second seal arrangement with a bristle pack upstream of two teeth is compared with the reference labyrinth. The swirl is evaluated experimentally from total and static pressure measurements in various axial and circumferential positions. Additionally, the axial swirl distribution is calculated using computational fluid dynamics (CFD). Here, the numerical model of the brush seal is based on the porous medium approach and is calibrated using the experimental values of the leakage and the bristle clearance by adjusting the thickness of the bristle pack. The calibrated CFD model is then used to study the impact of the brush seal on the swirl component of the sealing flow. The observed significant decrease of the swirl by the brush seal shows good agreement with the experimental data. The impact of changes in bristle pack clearance on the swirl is also investigated and compared with experimental evidence. The aim is to show that the brush seals have a natural tendency to interrupt seal swirl. They can therefore be used for swirl control in order to create a beneficial impact on the dynamic stability of turbomachines.}, language = {en} }