Experimental Study on Static and Dynamic Characteristics of Damper Seals Yieding High Rotor-Stability

• Project/Area Number: 08650169
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: 設計工学・機械要素・トライボロジー
• Research Institution: Nagaoka University of Technology
• Principal Investigator: KANEKO Satoru Nagaoka University of Technology, Department of Mechanical Engineering, Associate Professor, 工学部, 助教授 (90161174)
• Project Period (FY): 1996 – 1997
• Project Status: Completed (Fiscal Year 1997)
• Budget Amount: ¥2,200,000 (Direct Cost: ¥2,200,000); Fiscal Year 1997: ¥500,000 (Direct Cost: ¥500,000); Fiscal Year 1996: ¥1,700,000 (Direct Cost: ¥1,700,000)
• Keywords: Damper seals / Honeycombed-Holes-Pattern / Hole depth / Leakage flow rate / Dynamic fluid force / Dynamic coefficients

Research Abstract

In order to improve the seal stability characteristics, the experimental investigation of the static and dynamic characteristics has been developed for the damper seals with honeycombed-holes-pattern. The seals used for the tests are three types of the damper seals with different hole depth (damper seal I : 30mum, damper seal II : 400mum, damper seal III : 500mum in depth) and an annular plain seal (smooth surface). All test seals have approximately the same minimum redial clearance.
The results obtainded rea as follows :
(1) The leakage flow Q increases with the pressure difference between the inlet and outlet end of the seal, whereas the effect of rotor spinning velocity omega on Q is not significant. Under the same condition, Q for the damper seals is only about 2/3 that of the an nular plain seal, and it decreases with an indrease in the hole depth.
(2) The radial reaction fluid-force for the damper seal II is almost the same as that for the annular plain seal, and is larger than thos e for the other damper seals. All damper seals yield larger tangenial reaction fluid-force than the annular plain seal.
(3) The instability range of OMEGA/omega (OMEGA : rotor whirling velocity) for the damper seals is not significantly affected by omega, while that for the annular plain seal increases with omega. This suggests that the effect of the inlet swirl on the circumferential flow in the seal clearance is qualitatively small for the damper seals as compared to that for the annular plain seal.
(4) As compared to the annular seal, an increase in the main damping coefficient has been obtained by approximately 70 percent for the damper seal I,by approximately 20 percent for the damper seal II and by approximately 40 percent for the damper seal III.
(5) The damper seals have better leakage performance than the annular plain seal. Furthemore, the damper seal II shows better dynamic characteristics than the other damper seals and the annular plain seals from the viewpoint of yielding higher rotor-stability. This suggests that a suitable hole depth exists for the damper seals with the honeycombed-holes-pattern.