• Title/Summary/Keyword: hydrodynamic performance

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Effects of the Air Volume in the Air Chamber on the Performance of Water Hammer Pump System

  • Saito, Sumio;Takahashi, Masaaki;Nagata, Yoshimi
    • International Journal of Fluid Machinery and Systems
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    • v.4 no.2
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    • pp.255-261
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    • 2011
  • Recently, as global-scale problems, such as global warming and energy depletion, have attracted attention, the importance of future environmental preservation has been emphasized worldwide, and various measures have been proposed and implemented. This study focuses on water hammer pumps that can effectively use the water hammer phenomenon and allow fluid transport without drive sources, such as electric motors. An understanding of operating conditions of water hammer pumps and an evaluation of their basic hydrodynamic characteristics are significant for determining whether they can be widely used as an energy-saving device in the future. However, conventional studies have not described the pump performance in terms of pump head and flow rate, common measures indicating the performance of pumps. As a first stage for the understanding of water hammer pump performance in comparison to the characteristics of typical turbo pumps, the previous study focused on understanding the basic hydrodynamic characteristics of water hammer pumps and experimentally examined how the hydrodynamic characteristics were affected by the inner diameters of the drive and lift pipes and the angle of the drive pipe. This paper suggests the effect of the air volume in the air chamber that affects the hydrodynamic characteristics and operating conditions of the water hammer pump.

Numerical Investigation on Hydrodynamic Characteristics of a Centrifugal Pump with a Double Volute at Off-Design Conditions

  • Shim, Hyeon-Seok;Kim, Kwang-Yong
    • International Journal of Fluid Machinery and Systems
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    • v.10 no.3
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    • pp.218-226
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    • 2017
  • Severe radial thrust under off-design operating conditions can be a harmful factor for centrifugal pumps. In the present work, effects of geometry of a double volute casing on the hydrodynamic performance of a centrifugal pump have been investigated focusing on off-design conditions. Three-dimensional steady Reynolds-averaged Navier-Stokes analysis was carried out by using shear stress transport turbulence model. Numerical results for the hydrodynamic performance of the centrifugal pump were validated compared with experimental data. The hydraulic efficiency and radial thrust coefficient were used as performance parameters to evaluate the hydrodynamic characteristics of the centrifugal pump. The cross-sectional area ratio of the volute casing, the expansion coefficient of the rib structure, the distance between the rib starting point and volute entrance, and radius and width of the volute entrance, and length of the rib structure, were selected as geometric parameters. Results of the parametric study show that the performance parameters are significantly affected by the geometric variables and operating conditions. Optimal configurations of the double volute casing based on the design of experiments technique show outstanding performance in terms of the efficiency and radial thrust coefficient.

Hydrodynamic coefficients identification of underwater vehicle by means of an extended kalman filter (확장칼만필터를 이용한 수중운동체의 유체계수식별)

  • 이동권;최중락;양승윤
    • 제어로봇시스템학회:학술대회논문집
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    • 1991.10a
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    • pp.611-615
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    • 1991
  • A technique for estimation of the hydrodynamic parameter of an underwater vehicle is presented. An extended, augmented Kalman Filter is used to extract the hydrodynamic parameter. Computer generated data were used for the measurement information in lieu of actual run data. The feasibility of identifying values of the hydrodynamic parameter of an underwater vehicle is studied. Computer simulation are done in order to validate the performance of the proposed algorithm.

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Hydrodynamic Performance Test of a Turbopump Assembly (터보펌프 조립체의 수력 성능 시험)

  • Hong, Soon-Sam;Kim, Dae-Jin;Kim, Jin-Sun;Kim, Jin-Han
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.32 no.4
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    • pp.249-254
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    • 2008
  • Hydrodynamic performance test of a turbopump for a liquid rocket engine is carried out. The turbopump is composed of an oxidizer pump, a fuel pump and a turbine, and the two pumps are driven by the turbine. In the test, water is used for the pumps as working media and air is used for the turbine. Performance parameters of pumps and a turbine are drawn, and a power balance between the pumps and the turbine are calculated. The calculation shows a good power balance, which implies that the pump component tests, the turbine component test and the assembly test are reliably performed. At the starting period of the test, pressure rise-flow rate curve of a pump gradually approaches the ideal curve which could be obtained by very slow starting.

Performance Evaluation of a Main Coolant Pump for the Modular Nuclear Reactor by Computational Fluid Dynamics (전산해석에 의한 일체형 원자로용 주냉각재 펌프의 성능분석)

  • Yoon Eui-Soo;Oh Hyoung-Woo;Park Sang-Jin
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.30 no.8 s.251
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    • pp.818-824
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    • 2006
  • The hydrodynamic performance analysis of an axial-flow main coolant pump for the modular nuclear reactor has been carried out using a commercial computational fluid dynamics (CFD) software. The prediction capability of the CFD software adopted in the present study was validated in comparison with the experimental data. Predicted performance curves agree satisfactorily well with the experimental results for the main coolant pump over the normal operating range. π Ie prediction method presented herein can be used effectively as a tool for the hydrodynamic design optimization and assist the understanding of the operational characteristics of general purpose axial-flow pumps.

The Effect of Oil Supply Conditions on the Dynamic Performance of a Hydrodynamic Journal Bearing

  • Son, Sang-Ik;Kim, Kyung-Woong
    • KSTLE International Journal
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    • v.10 no.1_2
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    • pp.6-12
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    • 2009
  • In this study, the effect of oil supply conditions on the dynamic performance of a hydrodynamic journal bearing is analyzed numerically. Axial length, circumferential length and location of oil grooves are considered as oil supply conditions. The perturbation equations of the perturbed film contents are obtained by applying Elrod's universal equation implementing JFO film rupture / reformation boundary conditions to Lund's infinitesimal perturbation method. The dynamic coefficients of a hydrodynamic journal bearing are calculated by solving the perturbation equations, and the linear stability analysis is carried out by using those for a variety of oil supply conditions.

Experimental Characterization of Hydrodynamic Bearing Spindle Motor for High Performance Hard Disk Drive (고성능 하드 디스크 드라이브 개발을 위한 유체베어링 스핀들 모터의 특성분석(현장개발사례: SAMSUNG HDD ′SPINPOINT POLARIS SERIES′))

  • Son, Young;Hwang, Tae-Yeon;Han, Tun-Sik;Kang, Seong-Woo;Morris, Frank
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.05a
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    • pp.930-935
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    • 2001
  • The experimental characterization of hydrodynamic bearing spindle motor is performed for the practical implementation of high-performance hard disk drive system. Firstly, the design concept of hydrodynamic bearing for the disk drive system is addressed including the herringbone grooved journal bearing, the spiral grooved thrust bearing, capillary seal design, and the viscous pumping of fluid. Secondly, the experimental evaluation is performed for the disk drive system in which the hydrodynamic bearing spindle motor is implemented and its dynamic performances are compared with conventional ball-bearing spindle motor. The key parameters include NRRO(Non Repeatable Run-Out), disk dynamics, acoustics, and resultant PES (Position Error Signal). Finally, the external gyro-exciting test results including 200k CSS(Continuous Start-Stop) on three angular attitudes(0,90, 180 degree) are presented in order to verify the practical reliability of disk drive system subject to the gyro-motion of hydrodynamic bearing spindle motor.

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Calculation of Turbulent Flows around a Submarine for the Prediction of Hydrodynamic Performance

  • Kim, Jin;Park, Il-Ryong;Van, Suak-Ho;Kim, Wu-Joan
    • Journal of Ship and Ocean Technology
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    • v.7 no.4
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    • pp.16-31
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    • 2003
  • The finite volume based multi-block RANS code, WAVIS developed at KRISO, is used to simulate the turbulent flows around a submarine with the realizable $\textsc{k}-\varepsilon$ turbulence model. RANS methods are verified and validated at the level of validation uncertainty 1.54% of the stagnation pressure coefficient for the solution of the turbulent flows around SUBOFF submarine model without appendages. Another SUBOFF configuration, axisymmetric body with four identical stem appendages, is also computed and validated with the experimental data of the nominal wake and hydrodynamic coefficients. The hydrodynamic forces and moments for SUBOFF model and a practical submarine are predicted at several drift and pitch angles. The computed results are in extremely good agreement with experimental data. Furthermore, it is noteworthy that all the computations at the present study were carried out in a PC and the CPU time required for 2.8 million grids was about 20 hours to get fully converged solution. The current study shows that CFD can be a very useful and cost effective tool for the prediction of the hydrodynamic performance of a submarine in the basic design stage.

Hydrodynamic Investigation of a Floating-type Monoleaflet Polymer Valve under Steady Flow Condition (정상유동에서 유동형 단엽폴리머 인공판막의 수력학적 성능평가)

  • 김준우;박복춘
    • Journal of Biomedical Engineering Research
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    • v.17 no.1
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    • pp.49-60
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    • 1996
  • An experimental investigation was performed under steady flow condition to assess hydrodynamic performance of floating-type monoleaflet polymer valves (MLPV) withdifferent leaflet thickness. The St. Jude Medical valve (SJMV) was also used for comparison test. Pressure drops of MLPVS are larger than those for other types of polymer valves and mechanical valves. Furthermore, the thicker is the leaflet thickness of the polymer valve, the larger are the corresponding pressure drop. The velocity profiles for MLPs reveal a large reversed flow region downward to the valve position. The maximum wall shear stresses of MLPVS at a flow rate of $30{\ell}$/min are in the range 50-130 dyn/$cm^2$, and the corresponding maximum Reynolds shear stresses are in the range of 100-500 dyn/$cm^2$, respectively, which are beyond the allowable limit clinically. In contrast, floating-type monoleaflet polymer valves show better hydrodynamic performance in leakage volume. From the designing point of view, it may be concluded that the optimum thickness of leaflet for better hydrodynamic performance is one of the Important parameters.

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Hydrodynamic Investigation of a Floating-type Monoleaflet Polymer Heart Valve under Steady Flow Condition (정상유동에서 유동형 단엽폴리머 인공심장판막의 수력학적 성능평가)

  • Pak, Bock-Choon;Kim, Joon-Woo;Baek, Byoung-Joon;Min, Byoung-Goo
    • Proceedings of the KOSOMBE Conference
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    • v.1995 no.05
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    • pp.241-246
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    • 1995
  • An experimental investigation was performed under steady flow condition to assess hydrodynamic performance of floating-type monoleaflet polymer valves (MLPV) with different leaflet thickness. The St. Jude Medical valve (SJMV) was also used for comparison tests. Pressure drops of MLPVs are larger than those for other types of polymer valves and mechanical valves. Furthermore, the thicker is the leaflet thickness of a polymer valve, the larger arc the corresponding press drop. The velocity profiles for MLPV reveal a large reversed flow region downward to the valve position. The maximum wall shear stresses of MLPVs at a flow rate of 30 l/min are in the range $54-130\;dyn/cm^2$, and the corresponding maximum. Reynolds shear stresses are in the range of $100-500\;dyn/cm^2$, respectively. Both arc beyond the allowable limit clinically. In contrast, floating-type monoleaflet polymer valves show better hydrodynamic performance in leakage volume. From the designing point of view, it can be concluded that the optimum thickness of leaflet for better hydrodynamic performance is one of the important parameters.

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