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RISS 인기검색어
- 검색키워드
- 저자 : Yuichiro Tokunaga (검색결과 3 건)
- 무료
- 기관 내 무료
- 유료
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Rotordynamic Characteristics of Floating Ring Seals in Rocket Turbopumps
Tokunaga, Yuichiro,Inoue, Hideyuki,Hiromatsu, Jun,Iguchi, Tetsuya,Kuroki, Yasuhiro,Uchiumi, Masaharu Korean Society for Fluid machinery 2016 International journal of fluid machinery and syste Vol.9 No.3
Floating ring seals offer an opportunity to reduce leakage flows significantly in rotating machinery. Accordingly, they have been applied successfully to rotating machinery within the last several decades. For rocket turbopump applications, fundamental behavior and design philosophy have been revealed. However, further work is needed to explore the rotordynamic characteristics associated with rotor vibrations. In this study, rotordynamic forces for floating ring seals under rotor's whirling motions are calculated to elucidate rotordynamic characteristics. Comparisons between numerical simulation results and experiments demonstrated in our previous report are carried out. The three-dimensional Reynolds equation is solved by the finite-difference method to calculate hydrodynamic pressure distributions and the leakage flow rate. The entrance loss at the upstream inlet of the seal ring is calculated to estimate the Lomakin effect. The friction force at the secondary seal surface is also considered. Numerical simulation results showed that the rotordynamic forces of this type of floating ring seal are determined mainly by the friction force at the secondary seal surface. The seal ring is positioned almost concentrically relative to the rotor by the Lomakin effect. Numerical simulations agree quite well with the experimental results.
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Rotordynamic Characteristics of Floating Ring Seals in Rocket Turbopumps
Yuichiro Tokunaga,Hideyuki Inoue,Jun Hiromatsu,Tetsuya Iguchi,Yasuhiro Kuroki,Masaharu Uchiumi 한국유체기계학회 2016 International journal of fluid machinery and syste Vol.9 No.3
Floating ring seals offer an opportunity to reduce leakage flows significantly in rotating machinery. Accordingly, they have been applied successfully to rotating machinery within the last several decades. For rocket turbopump applications, fundamental behavior and design philosophy have been revealed. However, further work is needed to explore the rotordynamic characteristics associated with rotor vibrations. In this study, rotordynamic forces for floating ring seals under rotor’s whirling motions are calculated to elucidate rotordynamic characteristics. Comparisons between numerical simulation results and experiments demonstrated in our previous report are carried out. The three-dimensional Reynolds equation is solved by the finite-difference method to calculate hydrodynamic pressure distributions and the leakage flow rate. The entrance loss at the upstream inlet of the seal ring is calculated to estimate the Lomakin effect. The friction force at the secondary seal surface is also considered. Numerical simulation results showed that the rotordynamic forces of this type of floating ring seal are determined mainly by the friction force at the secondary seal surface. The seal ring is positioned almost concentrically relative to the rotor by the Lomakin effect. Numerical simulations agree quite well with the experimental results.
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( Satoshi Takeuchi ),( Hidehisa Saeki ),( Shoji Tokunaga ),( Makoto Sugaya ),( Hanako Ohmatsu ),( Yuichiro Tsunemi ),( Hideshi Torii ),( Koichiro Nakamura ),( Tamihiro Kawakami ),( Yoshinao Soma ),( E 대한피부과학회 2012 Annals of Dermatology Vol.24 No.2
Background: Pruritis caused by atopic dermatitis (AD) is not always well controlled by topical corticosteroid therapy, but use of tacrolimus often helps to soothe such intractable pruritis in clinical settings. Objective: To determine the anti-pruritic efficacy of topical tacrolimus in treating AD in induction and maintenance therapy. Methods: Prior to the study, patients were randomly allocated into two groups, induction therapy followed by tacrolimus monotherapy maintenance, and induction therapy followed by emollient- only maintenance. In the induction therapy, the patients were allowed to use topical tacrolimus and emollients in addition to a low dose (<10 g/week) of topical steroids. Patients showing relief from pruritis were allowed to proceed to maintenance therapy. Recurrence of pruritis in maintenance therapy was examined as a major endpoint. Results: Two-thirds of patients (44/68; 64.7%) showed relief from pruritis after induction therapy. Pruritis recurred in 23.8% (5/21) of the tacrolimus monotherapy group and in 100% (21/21) of the emollient group during maintenance period, a difference that was statistically significant. Conclusion: Use of topical tacrolimus is effective in controlling pruritis of AD compared to emollient. (Ann Dermatol 24(2) 144∼150, 2012)
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