A flat-plate tester was used to measure the friction factor behavior for a hole-pattern roughened surface apposed to a smooth surface. The tests were executed to characterize the friction factor behavior of annular seals that use a roughened-surface stator and a smooth rotor. Friction factors were o...
A flat-plate tester was used to measure the friction factor behavior for a hole-pattern roughened surface apposed to a smooth surface. The tests were executed to characterize the friction factor behavior of annular seals that use a roughened-surface stator and a smooth rotor. Friction factors were obtained from measurements of the mass flow rate and static pressure measurements along the smooth and roughened surfaces. In addition, dynamic pressure measurements were made at four axial locations at the bottom of individual 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 configurations 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 configurations, the friction factor remains largely 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 observed for smooth-on-smooth or smooth-on-rough configurations. When the phenomenon was observed, dynamic pressure measurements showed a peak-pressure oscillation at the calculated Helmholtz frequency of the holes.
A flat-plate tester was used to measure the friction factor behavior for a hole-pattern roughened surface apposed to a smooth surface. The tests were executed to characterize the friction factor behavior of annular seals that use a roughened-surface stator and a smooth rotor. Friction factors were obtained from measurements of the mass flow rate and static pressure measurements along the smooth and roughened surfaces. In addition, dynamic pressure measurements were made at four axial locations at the bottom of individual 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 configurations 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 configurations, the friction factor remains largely 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 observed for smooth-on-smooth or smooth-on-rough configurations. When the phenomenon was observed, dynamic pressure measurements showed a peak-pressure oscillation at the calculated Helmholtz frequency of the holes.
참고문헌 (16)
0742-4795 ASME J. Eng. Gas Turbines Power Kleynhans 119 4 949 10.1115/1.2817079 The Acoustic Influence of Cell Depth on the Rotordynamic Characteristics of Smooth-Rotor/Honeycomb-Stator Annular Gas Seals
Journal for Power and Mechanical Engineering Lomakin 14 4 1 Calculation of Critical Number of Revolutions and the Conditions Necessary for Dynamic Stability of Rotors in High-Pressure Hydraulic Machines When Taking Into Account Forces Originating in Sealings
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0742-4787 Trans. ASME, J. Tribol. Childs 121 42 10.1115/1.2833809 Test Results for Liquid ‘Damper’ Seals Using a Round-Hole Roughness Pattern for the Stators
0742-4787 Trans. ASME, J. Tribol. D’Souza 124 524 10.1115/1.1456086 A Comparison of Rotordynamic-Coefficient Predictions of Annular Honeycomb Gas Seals Using Different Friction-Factor Models
10.1115/GT2009-60337 Keith, G., Bhattacharjee, P., Nielsen, K., Ha, T. -H., Childs, D., and Platt, J., 2009, “Friction Factor Jump in Honeycomb Seals Explained by Flow-Acoustic Interactions,” ASME Paper No. GT2009-60337.
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