• International Journal of Fluid Machinery and Systems
• /
• v.2 no.2
• /
• pp.121-126
• /
• 2009

The internal flow field in a centrifugal pump working at the several flow conditions has been measured by using the particle image velocimetry (PIV) technique with the laser induced fluorescence (LIF) particles and the refractive index matched (RIM) facilities. The impeller of the centrifugal pump has an outlet diameter in 100mm, and consists of six two-dimensional curvature backward swept blades of constant thickness. Measured results give reliable flow patterns in the pump. It is obvious that application of LIF particle and RIM are the key methods to obtain the right PIV measured results in pump internal flow.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.15 no.5
• /
• pp.594-600
• /
• 2012

In this study, the mathematical model of the underwater discharge system using a centrifugal pump was derived and the rotating speed profiles of the pump which satisfied the discharge performance requirements were obtained through the underwater discharge simulations. The simulation results showed that the dynamic characteristics of a projectile were greatly affected by the rotational speed of the pump, however, hardly by the discharge depth. It is anticipated that the simulation model can be used to derive the design parameters and analyze the performance concerning the underwater discharge system using a centrifugal pump.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
• /
• 1999.05a
• /
• pp.151-157
• /
• 1999

In this study, tile characteristics of three dimensional flow fields in centrifugal flump impeller are investigated by numerically. Detailed analysis and understanding of flow field in centrifugal pump are very important to predict performance of components. The three dimensional viscous fluid flow in centrifugal pump is distingushed isentropic process region from irreversible process region by wall shear effect, secondary flow, centrifugal and Coriolis forces, variation of boudary layers. Development of low momentum region by viscous fluid flow in the centrifugal impeller causes stall and blockage which is irreversible process region, and resulting in decrease of the performance and efficiency of centrifugal pump. Especially, the result is that Coriolis and centrifugal forces are most powerful factors which are increasing the irreversible region.

• International Journal of Fluid Machinery and Systems
• /
• v.7 no.4
• /
• pp.142-150
• /
• 2014

In the cardiopulmonary support system with an ECMO (extracorporeal membrane oxygenation), a higher pump head is demanded for a blood pump. In order to realize a blood pump with higher pump head, higher anti-hemolysis and thrombosis performances, a study on the development of unprecedented multistage blood pump was conducted. In consideration of the application of the blood pump for pediatric patients, a miniature two-stage centrifugal blood pump with the impeller's diameter of 40mm was designed and the performance was examined in experiments and computations. Some useful knowledge for a design of the blood pump with higher anti-hemolysis and thrombosis performances was obtained.

• International Journal of Fluid Machinery and Systems
• /
• v.10 no.3
• /
• pp.218-226
• /
• 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.

• International Journal of Fluid Machinery and Systems
• /
• v.1 no.1
• /
• pp.57-63
• /
• 2008

To optimize the stationary components in the multistage centrifugal pump, the effects of the return vane profile on the performances of the multistage centrifugal pump were investigated experimentally, taking account of the inlet flow conditions for the next stage impeller. The return vane, whose trailing edge is set at the outer wall position of the annular channel downstream of the vane and which discharges the swirl-less flow, gives better pump performances. By equipping such return vane with the swirl stop set from the trailing edge to the main shaft position, the unstable head characteristics can be also suppressed successfully at the lower discharge. Taking the pump performances and the flow conditions into account, the impeller blade was modified so as to get the shock-free condition where the incidence angle is zero at the inlet.

• The KSFM Journal of Fluid Machinery
• /
• v.15 no.6
• /
• pp.46-50
• /
• 2012

A high-speed centrifugal pump requires more attention to the control of its axial thrust due to the high discharge pressure than a conventional industrial pump. Vanes employed toward the rear cavity of the impeller can be an effective device to control the axial thrust of the pump. The vanes disturb circumferential flow of the cavity and it can modify the axial force acting on the impeller. In this paper, three types of vanes are installed in the high-speed centrifugal pump for liquid rocket engines and the thrust of the pump is measured with an additional thrust measurement unit. According to the results, shapes of cavity vanes have effects on the axial thrust of the pump. As the height of vanes increases, the outlet pressure of the rear floating ring seal decreases which results in a decrease of the thrust. On the other hand, head of the pump is almost same regardless of cavity vanes. Also, the pressure drop of the bypass pipeline increases when vanes are removed.

• Journal of Korean Society of Water and Wastewater
• /
• v.30 no.5
• /
• pp.481-489
• /
• 2016

Method of characteristic(MOC) has been widely used as a transient analysis technique for pressurized pipeline systems. There are substantial studies using MOC for the water hammer triggered through instantaneous valve closures, pump stoppage and pump startup for pipelines systems equipped with a centrifugal pump. Considering restrictions of MOC associated with courant number condition for complicated pipeline systems, an impulse response method(IRM) was developed in the frequency domain. this study implements the impact of centrifugal pump using transfer function in frequency domain approach. Using pump performance curve and the affinity law, this study formulated transfer functions which relate complex pressure head at upstream of pump system to that of downstream location. Simulations of simple reservoir-pump-valve system using IRM with formulated transfer function were similar to those obtained through MOC.

• International Journal of Fluid Machinery and Systems
• /
• v.6 no.1
• /
• pp.11-17
• /
• 2013

Mini centrifugal pumps having a diameter smaller than 100mm are employed in many fields. But the design method for the mini centrifugal pump is not established because the internal flow condition for these small-sized fluid machines is not clarified and conventional theory is not suitable for small-sized pumps. Therefore, mini centrifugal pumps with simple structure were investigated by this research. Splitter blades were adopted in this research to improve the performance and the internal flow condition of mini centrifugal pump which had large blade outlet angle. The original impeller without the splitter blades and the impeller with the splitter blades were prepared for an experiment. The performance tests are conducted with these rotors in order to investigate the effect of the splitter blades on performance and internal flow condition of mini centrifugal pump. On the other hand, a three dimensional steady numerical flow analysis is conducted with the commercial code (ANSYS-CFX) to investigate the internal flow condition in detail. It is clarified from experimental results that the performance of the mini centrifugal pump is improved by the effect of the splitter blades. Blade-to-blade low velocity regions are suppressed in the case with the splitter blades and total pressure loss regions are decreased. The effects of the splitter blades on the performance and the internal flow condition are discussed in this paper.

• Journal of KSNVE
• /
• v.10 no.3
• /
• pp.500-507
• /
• 2000

Dynamic forces due to mechanical and hydraulic related causes are always exerted on operating turbomachinery such as centrifugal pumps. To ensure the safety and the reliability of the pump. the magnitudes of the vibration must be kept within an acceptable limit. The focus of this paper is on the identification of the vibration behavior and the quantitative analysis of the hydraulic excitation forces. As the structure becomes more complex finite element analysis is essential to accurately predict the vibration characteristics and the excitation forces, This paper presents an experimental and analytical technique to find and solve to vibration problems in double volute double suction centrifugal pump. Measured vibration data due to the dynamic forces are presented and individual causes are identified, finally excitation forces of the pump are inversely estimated at each frequency on operating conditions.