• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.40 no.6
• /
• pp.409-415
• /
• 2016

In this study, we test the effects of the surface roughness on the hydro efficiency of double-suction centrifugal pumps ($Q=70.7m^3/min$, H = 87 m). The original surface of the impeller and inner casing were coated, resulting in surface-roughness reductions ranging from $100{\sim}110{\mu}m$ to $0{\sim}0.08{\mu}m$. We conducted experimental studies to measure the efficiency of the pumps and operating-pump electro energy variations with different surface roughness values. The experimental results showed that the efficiency of the pumps increased by about 0.8~1.79% and the electric energy of the operating pump was reduced by around 4.38 ~ 6.08%. These results indicate that the performance of the pumps depend largely on the surface roughness of the impeller and inner casing, and by reducing the surface roughness, we can improve the efficiency of the pump and reduce costs by reducing the electric energy consumption.

• The KSFM Journal of Fluid Machinery
• /
• v.13 no.6
• /
• pp.51-56
• /
• 2010

A numerical simulation is carried out to investigate the effect of flow rate variation and performance characteristics of double-suction centrifugal pump. Two types of pump which have different impeller inlet breadth and curvature of the shroud line consist of six blades impeller and shroud ring. Finite-volume method with structured mesh and $k-\omega$ Shear Stress Transport turbulence model was used to guaranty more accurate prediction of turbulent flow in the pump impeller. Total head, power and overall efficiency were calculated to obtain performance characteristics of two types of pump according to the variation of flow rate. From the results, impeller having smooth curve along the shroud line obtained good performance. The lower flow rate, the more circulation region, flow unsteadiness and complicate flow pattern are observed. Complicated internal flow phenomena through impellers such as flow separation, pressure loss, flow unsteadiness and performance are investigated and discussed.

• 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.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.8 s.179
• /
• pp.1931-1939
• /
• 2000

Operating excitation forces of the linear vibratory system are normally determined by direct measurement techniques using load cells, strain gauges, etc. But, hydraulic forces of the rotating turbomachinery such as centrifugal pumps are exerted on an impeller due to asymmety of the flow by the interaction between pump impeller and volute. So, investigations of wide range of hydraulic designs and geometric deviations are difficult by direct method. This paper presents a hybrid approach for fourier transformed operational excitation forces, which uses pseudo-inverse matrix of the transfer matrix for the system and the measured vibrational data with standard installed pump. The determination of the transfer function matrix is based on a linear rotor/stationary system and steady state harmonic response in finite element analysis. And, vibrational data is collected in both vertical and horizontal directions at inboard and outboard bearing housings. The results of the process may be enhanced by making acceleration measurements at many more locations than there are forces to be determined.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.5 no.6
• /
• pp.103-110
• /
• 1997

A performance prediction method is presented for single(double) suction centrifugal pumps with a review of loss correlations given in the previous open literature. Most of the loss analyses mentioned in the present study are one dimensional and this paper investigates several modeling schemes and shows that a fairly good prediction can be achieved by a proper selection of the most important flow parameters resulting from a mean streamline analysis. Predictions of the trends of total head- capacity and pump efficiency-capacity curves agree well with the experimental data in almost the full range of operating conditions. The prediction method developed through this study can serve as a tool to ensure good matching between parts and it can assist the understanding of the operational characteristics of general purpose centrifugal pumps.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.23 no.1
• /
• pp.104-111
• /
• 2017

This research focuses on simulation and visualization of flow field characteristics inside a centrifugal pump. The 3D numerical analysis was carried out by using a numerical CFD tool, addressing a Reynolds Average Navier-Stock code with a standard k-${\varepsilon}$ two-equation turbulence model. The simulation accounts for friction head loss due to rough walls at suction, impeller, discharge areas and volumetric head loss at impeller wear ring. A comparison of performance curves between simulation and experimentation is included, and it reveals a same trend of those results with a small difference of maximum 5 %. At best efficiency point, velocity vectors are smooth but it changes significantly under off-design point, a strong recirculation appears at the outlet of impeller passages near tongue area. A relatively uniform preassure distribution was observed around the impeller in despite of the tongue. Within the volute, because of its geometry, spiral vortexes formed, proving that the flow field in this region was relatively turbulent and unsteady.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.23 no.4
• /
• pp.400-406
• /
• 2017

The model used in this study was reversed to analyze the cause of excessive damage that occurred inside the rotating system and pipe system of a centrifugal-type seawater pump on a ship. For this purpose, internal flow analysis on a cooling seawater pump was performed using CFD. As a result, the shape and boundary conditions of the target pump were set by reverse engineering, and pump efficiency at a design operating point of $125m^3/h$ was calculated as 85.3 % with a head of 32.0 m. The maximum efficiency point of the target pump was estimated to be 86.2 % at $150m^3/h$, but this differed from the actual operating point. At $112.5m^3/h$, which was the lowest flow point, flow was unstable due to the characteristics of the low flow point and analysis convergence was not good. The purpose of this study was to clarify the cause of ongoing cavitation in seawater pumps and piping systems in operation. Future research will be needed to clarify causes for pipe systems in the future by performing calculations for the total piping system of an inlet and outlet, in addition to measuring the flow rate of each branch pipe.