Friction-Factor Data for Flat-Plate Tests of Smooth and Honeycomb Surfaces

Ha, Tae Woong; Childs, Dara W.

doi:10.1115/1.2920941

Cited by 31 publications

(12 citation statements)

References 7 publications

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“…This parameter is independent of the values of the inlet parameters, and simplifies the comparison of results. The Reynolds number in the case of labyrinth seals is defined as follows (Ha, 1992), (Massini, 2014): (4) Where d h = 2·s is the hydraulic diameter, v ax -the axial component of velocity, and π is the ratio of a circle's circumference to its diameter. Both formulae should give the same result.…”

Section: Computational Fluid Dynamics Approachmentioning

confidence: 99%

Experimental and numerical validation study of the labyrinth seal configurations

Szymański

Dykas

Wróblewski

et al. 2017

European Conference on Turbomachinery Fluid Dynamics and Hermodynamics

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This article presents a validation study of the labyrinth seal testing. Both experimental and numerical simulations are performed. Literature data focused on simple labyrinth seals are surveyed, and two different configurations widely described in literature are investigated: a labyrinth seal with two straight fins against a smooth and a honeycomb land and a seal with three straight fins against a smooth land only. For experimental testing the vacuum-feeding test rig is used, with the high-precision Hot Wire Thermoanemometry method applied for the mass flow evaluation. The dimensions of specimens described in literature are adapted to the in-house test rig conditions, meeting all the geometrical requirements mentioned by the author. The computational method is based on the Reynolds Averaged Navier Stokes scheme, with various turbulence models. The results of the simulations show good agreement with the in-house experiment, whereas some discrepancies are found compared to literature data. KEYWORDS LABYRINTH SEAL, HONEYCOMB, SECONDARY FLOWS, EXPERIMENT, TEST RIG NOMENCLATURE

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Section: Computational Fluid Dynamics Approachmentioning

confidence: 99%

Experimental and numerical validation study of the labyrinth seal configurations

Szymański

Dykas

Wróblewski

et al. 2017

European Conference on Turbomachinery Fluid Dynamics and Hermodynamics

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“…As stated earlier, this study was initiated to examine the friction-factor jump phenomenon reported by Ha and Childs [5]. Ha observed this phenomenon in 34% of his test cases for flow between apposed honeycomb surfaces.…”

Section: Hole-on-hole Tests To Produce a Friction-factor Jumpmentioning

confidence: 90%

“…Note that Eq. (5) is the Darcy-Weisbach friction factor definition versus the Fanning definition used by Ha and Childs [5].…”

Section: Caiculating Wall Friction Factors From Flat-plate Test Datamentioning

confidence: 99%

Friction Factor Behavior From Flat-Plate Tests of Smooth and Hole-Pattern Roughened Surfaces With Supply Pressures up to 84 bars

Childs

Kheireddin

Phillips

et al. 2011

Journal of Engineering for Gas Turbines and Power

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A flat-plate tester was used to measure the friction factor behavior for a hole-pattern roughened surface opposed to a smooth surface. The tests were executed to characterize the friction factor behavior of annular seals that use a roughened-sutfdce stator and a smooth rotor. Friction factors were obtained from measurements of the mass flow rate and static pressure measurements along the smooth and toughened surfaces. In addition, dynamic pressure measurements were made cit four axial locatiotts at the bottom of individttal holes and at facing locations in the smooth plate. The test facility is described, and a procedure for determining the friction factor is reviewed. Three clearances were investigated: 0.635 mm, 0.381 mm, and 0.254 mm. Tests were conducted with air at three different inlet pressures (84 bars, 70 bars, and 55 bars), producing a Reynolds numbers range from 50,000 to 700,000. Three surface conflgurations were tested, including smooth-on-smooth, smooth-on-hole, and hole-on-hole. The hole-pattern plates are identical with the exception of the hole depth. For the smooth-on-smooth and smooth-on-hole conflgurations, the friction factor remains largelv constant or increases slightly with increasing Reynolds numbers. The friction factor increases as the clearance between the plates increases. The test program was initiated to investigate a friction-factor jump phenomenon cited by Ha et al. (1992, "Friction-Factor Characteristics for Narrow-Channels With Honeycomb Surfaces, " Trans. ASME, J. TriboL, 114, pp. 714-721) in test results from a flat-plate tester where, at elevated values of Reynolds numbers, the friction factor began to increase steadily with increasing Reynolds numbers. They tested apposed honeycomb surfaces. For the present tests, the phenomenon was also observed for tests of apposed roughened surfaces but was not obserx'ed for smooth-on-smooth or smooth-cmrough configurations. When the phenomenon was observed, dynamic pressure measurements showed a peak-pressure oscillation at the calculated Helmholtz frequency of the

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“…The results of equation (3) were developed by Yamada(1962) from measurements of flow between rotating cylinders. The results of equation (4) are from Ha(1989) and are based on flat-plate test results for the honeycomb cell dimensions used in this study. When friction factors based on the coefficients of equation (4) are plotted on a Moody diagram, the equivalent relative roughness parameter is about 0.03.…”

Section: Discussionmentioning

confidence: 99%

Seal-Rotordynamic-Coefficient Test Results for a Model SSME ATD-HPFTP Turbine Interstage Seal With and Without a Swirl Brake

Childs

Ramsey

1991

Journal of Tribology

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Test results are presented and compared to theory for a model Space Shuttle Main Engine(SSME) Alternate Turbopump Development(ATD) High-Pressure Fuel Turbopump (HPFTP) with and without swirl brakes. Tests are conducted with s u p ply pressures out to 18.3 bars and speeds out to 16,000 rpm. Seal back pressure is controlled to provide four pressure ratios at all supply pressures. Three inlet guide vanes are used to provide the following three fluid prerotation cases: (a) no prerotation, (b) moderate prerotation in the direction of rotation, and (c) high prerotation in the direction of rotation. Test results demonstrate the pronounced favorable influence of the swirl brake in reducing the seal destabilizing forces. Without the swirl brake, the cross-coupled stiffness k increases monotonically with increasing inlet tangential velocity. With the swirl brake, k tends to either be constant or decrease with increasing inlet tangential velocity. Direct damping either increases or remains relatively constant when the swirl brake is introduced. Direct stiffness is relatively unchanged. No measurable differences in leakage were detected for the seal with and without the swirl brake.Comparisons between Scharrer's(l988) theory and measurements for the seal without a swirl brake indicate that the predictions can be used to provide design guide1ine.s only. Specific predict ions for rotor dynamic coefficients should be treated cautiously, since systematic differences were observed between theory and experiment due to changes in running speed, supply pressure, and pressure ratio.

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Friction-Factor Data for Flat-Plate Tests of Smooth and Honeycomb Surfaces

Cited by 31 publications

References 7 publications

Experimental and numerical validation study of the labyrinth seal configurations

Experimental and numerical validation study of the labyrinth seal configurations

Friction Factor Behavior From Flat-Plate Tests of Smooth and Hole-Pattern Roughened Surfaces With Supply Pressures up to 84 bars

Seal-Rotordynamic-Coefficient Test Results for a Model SSME ATD-HPFTP Turbine Interstage Seal With and Without a Swirl Brake

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