Relative Performance Comparison Between Baseline Labyrinth and Dual Brush Compressor Discharge Seals in a T-700 Engine Test

Hendricks, R. C.; Griffin, Thomas A.; Kline, Teresa R.; Csavina, Kristine R.; Pancholi, Arvind; Sood, Devendra

doi:10.1115/94-gt-266

Cited by 23 publications

(16 citation statements)

References 3 publications

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“…This damping is much larger than was measured for brush seals earlier by Conner and Childs, (1990), with fewer bristles and a different backing plate. It is hypothesized that the bristles became more packed together and held against the backing plate by the pressure drop (Hendricks et. al., 1994).…”

Section: Numerical and Experimental Resultsmentioning

confidence: 99%

“…but previous tests (Connor and Childs, 1990) have shown very little damping capacity. More recently, engine tests were made to compare the forward-facing labyrinth seal with dual-brush seals installed as compressor discharge seals (Hendricks, et al, 1994). The leakage of the brush seals was only 40% of the labyrinth leakage, so specific fuel consumption was improved three to five percent.…”

Section: Introductionmentioning

confidence: 99%

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Hybrid Brush Pocket Damper Seals for Turbomachinery

Laos

Vance

Buchanan

1999

Volume 4: Manufacturing Materials and Metallurgy; Ceramics; Structures and Dynamics; Controls, Diagnostics and Instrumentation;

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Pocket damper seals perform a dual function: both sealing the pressurized gas around a rotating shaft and providing large amounts of vibration damping. The annular cavity between the labyrinth seal teeth is subdivided into separate annular cavities around the circumference of the rotor by partitioning walls. Also, the upstream and downstream teeth have different radial clearances to the rotor. These seals have been shown to provide a remarkable amount of direct damping to attenuate vibration in turbomachinery, but they generally leak more than conventional labyrinth seals if both seals have the same minimum clearance. Conversely, brush seals allow less than half the leakage of labyrinth seals, but published test results show no significant amount of damping. They are considered to be a primary choice for the seals in new aircraft engine designs because of their low leakage. This paper will describe a recently invented hybrid brush/pocket damper seal that combines high damping with low leakage. Previous brush seal results were studied and calculations were made to select a brush seal to combine with the pocket damper design. The result is a hybrid seal with high damping and low leakage. A special design feature can also allow active vibration control as a bonus benefit,A computer code written for the original pocket damper seal was modified to include the brush element at the exit blade. Results from the computer code indicate that the hybrid seal can have less leakage than a six bladed (or 6 knives) labyrinth seal along with orders of magnitude more damping.Experimental evaluations of the damping and leakage performance of the hybrid seal are being conducted by the authors. The experimental work reported here tested the damping capability of the new hybrid brush seal by exciting the seal journal through an impedance head. A conventional six-bladed labyrinth seal of the same working dimensions was also tested. The brush hybrid pocket damper seal is found to leak less than the labyrinth seal while producing two to three times more damping than the original pocket damper seal. (orders of magnitude more than the conventional labyrinth).

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Section: Numerical and Experimental Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hybrid Brush Pocket Damper Seals for Turbomachinery

Laos

Vance

Buchanan

1999

Volume 4: Manufacturing Materials and Metallurgy; Ceramics; Structures and Dynamics; Controls, Diagnostics and Instrumentation;

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“…Their comparisons between measured and predicted flows through the seal was generally good considering the overall simplicity of their theoretical model. Handericks et al [9] carried out experiments on dual brush and labyrinth compressor discharge seals in a T-700 engine test.. The test condition included compressor discharge pressure up to 1 MPa, temperatures 407C, operating speeds up to 43000 rpm, and surface speeds up to 160 m/s with dry ambient air as the working fluid.…”

Section: Introductionmentioning

confidence: 99%

Advanced seal design for rotating machinery

Saber¹

2011

AJSIR

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Labyrinth and more recently brush seals have been used extensively in high speed rotating machinery. Development is still in progress to reduce the leakage rate, and the frictional resistance of these seals beside the awareness of their stability characteristics. A seal very similar to the brush seal geometry is proposed here. It is composed of fine strips replacing the wires of the ordinary brush seal. A simple theoretical model for this strip seal is put forward here based on the assumption that the flow through it is steady laminar and incompressible. A Reynolds like equation is devised, governing the pressure inside the seal. Calculations of the leakage rate and the friction resistance are carried out for the various parameters considered and the results are presented and discussed in detail along with comparisons with previous work. It is shown in this work that the strip angle has a major effect on the performance of the seal as well as on the friction resistance. It is found that the larger the angle the lesser the leakage rate and the larger the friction force. The optimum value for minimum leakage is 90 o but for mechanical stability and durability reasons it should be smaller. It is also found that the wider the strips the lesser the leakage rate for all values of the strip angle. The opposite holds for the friction resistance. The spacing between the strips has a minor effect on the leakage rate for small values of the strip angle but for larger values of the angle the increase in leakage becomes considerable when increasing the spacing for angles of order 70 o . Comparisons with previous works on different types of seals showed that the present seal model can satisfactorily be implemented in practice.

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“…An engine with reduced secondary flow leakage past seals produces approximately 4 to 6 percent more power while reducing the specific fuel consumption by 3 to 5 percent. 1, 2 Brush seals have been generating a great deal of interest as replacements for labyrinth seals in secondary air flow systems due to their potential for improved air-to-air sealing and their tolerance of shaft excursions. Current research has demonstrated that a reduction of 90 percent in internal leakage can be obtained by replacing the best knife edged labyrinth seal with a brush seal.…”

Section: Introductionmentioning

confidence: 99%

A New Tribological Test for Candidate Brush Seal Materials Evaluation

Fellenstein

DellaCorte

1996

Tribology Transactions

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A new tribological test for candidate brush seal materials evaluation has been developed. The sliding contact between the brush seal wires and their mating counterface journal is simulated by testing a small tuft of wire against the outside diameter of a high speed rotating shaft. The test configuration is similar to a standard block on ring geometry.The new tester provides the capability to measure both the friction and wear of candidate wire and counterface materials under controlled loading conditions in the gram to kilogram range. A wide range oftest condition speeds (l to 27 m/s), temperatures (25 to 700°C), and loads (0.5 to 10 N) enables the simulation of many of the important tribological parameters encountered by turbine engine brush seals. This paper describes the new test rig and specimen configuration and presents initial data for candidate seal materials comparing tuft test results and wear surface morphology to field tested seal components.

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Relative Performance Comparison Between Baseline Labyrinth and Dual Brush Compressor Discharge Seals in a T-700 Engine Test

Cited by 23 publications

References 3 publications

Hybrid Brush Pocket Damper Seals for Turbomachinery

Hybrid Brush Pocket Damper Seals for Turbomachinery

Advanced seal design for rotating machinery

A New Tribological Test for Candidate Brush Seal Materials Evaluation

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