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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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The KSFM Journal of Fluid Machinery
Journal Basic Information
Journal DOI :
Korean Fluid Machinery Association
Editor in Chief :
Volume & Issues
Volume 16, Issue 6 - Dec 2013
Volume 16, Issue 5 - Oct 2013
Volume 16, Issue 4 - Aug 2013
Volume 16, Issue 3 - Jun 2013
Volume 16, Issue 2 - Apr 2013
Volume 16, Issue 1 - Feb 2013
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Operational Vibration Experiment and Analysis of a Small Vertical-Axis Wind Turbine Considering the Effect of a Tower Stiffness
Choo, Heon-Ho ; Sim, Jae-Park ; Oh, Min-Woo ; Kim, Dong-Hyun ;
The KSFM Journal of Fluid Machinery, volume 16, issue 3, 2013, Pages 5~9
DOI : 10.5293/kfma.2013.16.3.005
In this study, operational vibration experiment and analysis have been conducted for the 4-blade small vertical-axis wind turbine (VAWT) including the effect of tower elastic behavior. Computational structural dynamics analysis method is applied to obtain Campbell diagram for the VAWT with elastic tower. An open type wind-tunnel is used to change and keep the wind velocity during the ground test. Equivalent elastic tower is used to support the VAWT so that the effect of elastic stiffness of the tower can be considered in the present vibration experiment. Various excitation conditions with wind loads are considered and the dominant operating vibration phenomena are physically investigated in detail.
A Study on the Organic Rankine Cycle Using R245fa
Cho, Soo-Yong ; Cho, Chong-Hyun ; Kim, Jinhan ;
The KSFM Journal of Fluid Machinery, volume 16, issue 3, 2013, Pages 10~17
DOI : 10.5293/kfma.2013.16.3.010
The organic Rankine cycle has been widely used to convert the renewable energy such as the solar energy, the geothermal energy, or the waste energy etc., to the electric power. Some previous studies focused to find what kind of refrigerant would be a best working fluid for the organic Rankine cycle. In this study, R245fa was chosen to the working fluid, and the cycle analysis was conducted for the output power of 30kW or less. In addition, properties (temperature, pressure, entropy, and enthalpy etc.) of the working fluid on the cycle were predicted when the turbine output power was controlled by adjusting the mass flowrate. The configuration of the turbine was a radial-type and the supersonic nozzles were applied as the stator. So, the turbine was operated in partial admission. The turbine efficiency and the optimum velocity ratio were considered in the cycle analysis for the low partial admission rate. The computed results show that the system efficiency is affected by the partial admission rate more than the temperature of the evaporator.
Study on the Electromagnetic Excitation System for the Measurement of Dynamic Coefficients of Air Foil Bearing for High Speed Rotor
Park, Cheol-Hoon ; Choi, Sang-Kyu ; Ham, Sang-Yong ;
The KSFM Journal of Fluid Machinery, volume 16, issue 3, 2013, Pages 18~25
DOI : 10.5293/kfma.2013.16.3.018
Recently the requirement of long-term mobile energy source for mobile robot or small-sized unmanned vehicle is highly increased, and the micro turbine generator(MTG) which is known to have high energy and power density is under development. MTG is designed to have air foil bearing and high speed rotor of which operating speed is 400,000rpm. In the development stage of high speed rotor and bearing, stability analysis for the full operational speed range is essential and the dynamic coefficients such as stiffness and damping coefficients of bearing depending on the rotational speed are required for that. Although perturbation method is usually used to identify the dynamic coefficients, it`s not easy to give the perturbation to the high speed rotating rotor. In this study, we present the dynamic coefficients measurement system for air foil bearing which consists of electromagnets, gap sensors, high speed motor and controller. This measurement system can exert the sine sweep force to the rotor-bearing, measure the displacement of rotor and get FRF(Frequency response function) of rotor-bearing. The least square estimation method is applied to identify the dynamic coefficients of bearing from the measured frequency response at the different rpm and the identified dynamic coefficients for the wide rotational speed range are presented.
Analysis of Pre-Swirl Effect for Plain-Gas Seal Using CFD
Ha, Tae-Woong ;
The KSFM Journal of Fluid Machinery, volume 16, issue 3, 2013, Pages 26~31
DOI : 10.5293/kfma.2013.16.3.026
In present 3D CFD study, the method for determining leakage and rotordynamic coefficients of a plain-gas seal is suggested by using the relative coordinate system for steady-state simulation. In order to find the effect of pre-swirl speed at seal inlet, pre-swirl velocity is included as a parameter. Present analysis is verified by comparison with results acquired from Bulk-flow analysis code and published experimental results. The results of 3D CFD rotordynamic coefficients of direct stiffness(K) and cross-coupled stiffness(k) show improvements in prediction. As pre-swirl speed at seal inlet increases, k also increases to destabilize system. However, pre-swirl speed at seal inlet does not show sensitivity to the leakage and rotordynamic coefficients of K and damping(C).
Rotordynamic Analysis and Experimental Investigation of the Turbine-Generator System Connected with Magnetic Coupling
Kim, Byung Ok ; Park, Moo Ryong ; Choi, Bum Seok ;
The KSFM Journal of Fluid Machinery, volume 16, issue 3, 2013, Pages 32~38
DOI : 10.5293/kfma.2013.16.3.032
This paper deals with the study on the rotordynamic and experimental analysis of turbine-generator system connected with a magnetic coupling. Although magnetic coupling has been used to torque transmission of chemical processing pump rotating at under 3,600rpm, magnetic coupling in this study is applied to high-speed turbine-generator system using a working fluid that is refrigerant such as ammonia or R-124a. Results of rotordynamic design analysis are as follows. The first, shaft diameter nearest to outer hub of magnetic coupling has a big effect on the
critical speed of generator rotor. The second, if the
critical speeds of turbine rotor and generator rotor have enough to separation margin in comparison to rated speed, the
critical speed of turbine-magnetic coupling-generator rotor train has enough to separation margin regardless of connection stiffness of magnetic coupling. The analytical FE model is guaranteed by impact test on the prototype and condition monitoring such as measurements of vibration and bearing temperature is also performed.
Analysis of a Rim-Seal with a Semicircular Rib or Groove
Lee, Chung-Suk ; Moon, Mi-Ae ; Kim, Kwang-Yong ;
The KSFM Journal of Fluid Machinery, volume 16, issue 3, 2013, Pages 39~47
DOI : 10.5293/kfma.2013.16.3.039
Effect of semicircular rib or groove on the performance of a rim-seal was evaluated using three-dimensional Reynolds-averaged Navier-Stokes equations. The turbulence was modeled using the one-equation Spalart-Allmaras turbulence closure model. Reynolds number based on the axial chord of the turbine blade was 500,000 at the mainstream outlet. The numerical results for a sealing effectiveness was validated in comparison with experimental data. To examine the effect of the semicircular rib or groove on sealing effectiveness of the rim-seal, location and diameter of the rib or groove were selected as the parameters to be performed. The rim-seals with the semicircular groove showed a higher sealing effectiveness than that with the semicircular rib. The semicircular groove installed on the stator side showed best sealing effectiveness among the numerical simulation results.
A Comparative Study of Waste Collection Technologies
Jung, Young Hoon ; Suh, Sang-Ho ; Kim, Hyoung-Ho ;
The KSFM Journal of Fluid Machinery, volume 16, issue 3, 2013, Pages 48~53
DOI : 10.5293/kfma.2013.16.3.048
Due to the urbanization, lots of people are living in cities. It is very convenient to live in the cities for the people but at the same time, the highly populated city has several environmental problems. During delivery process of large amount of municipal waste generated from the cities, the automobile emission and traffic jam have been occurred. The waste collection in the cities has been mainly done by using labour force and delivery truck. This is the conventional waste collection up to now. Recently, new technologies like automated waste collection system and capsule transportation have been introduced. Conventional waste collection mainly relied on the labour force and truck delivery does not need to invest a lot of money for the start-up. However, it requires to pay the operational cost both for the labour force and the truck delivery. On the contrary to this conventional waste collection, the automated waste collection and capsule transportation require high initial investment cost. However, the automated waste collection and capsule transportation can reduce significantly the pollutants emission, traffic jam by the waste trucks and actual waste collection cost per ton. In dealing with the waste collection in the cities, new waste collection technologies could be properly combined with the conventional waste collection for the effective municipal waste treatment.