Centrifugal Pump Performance During Transient Operation

1995 ◽  
Vol 117 (1) ◽  
pp. 123-128 ◽  
Author(s):  
P. J. Lefebvre ◽  
W. P. Barker
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Rotational Speed ◽  
Hydrodynamic Performance ◽  
Test Facility ◽  
Transient Operation ◽  
Transient Effects ◽  
Pump Impeller ◽  
Simultaneous Control ◽  
Steady State Operation

The effect of transient operation on the hydrodynamic performance of a centrifugal pump impeller was investigated experimentally. All experiments were conducted in the Naval Undersea Warfare Center’s Impeller Test Facility (ITF), which was designed and built for transient and steady-state operation impeller research. The ITF provides transient operation through simultaneous control of both impeller rotational speed and flow rate over time. The impeller was accelerated from rest with peak angular accelerations up to 720 radians/s2 and inlet flow mean accelerations up to 1.7 g, reaching a peak rotational speed of 2400 rpm and a flow rate of 416 l/s. The impeller was then decelerated to rest. Results showed substantial transient effects in overall impeller performance and demonstrated that the quasisteady assumptions commonly used for the design of impellers that operate under high transient (accelerating or decelerating) conditions are not valid.

scholarly journals Large Eddy Simulation of Periodic Transient Pressure Fluctuation in a Centrifugal Pump Impeller at Low Flow Rate

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 311
Author(s):  
Renfei Kuang ◽  
Xiaoping Chen ◽  
Zhiming Zhang ◽  
Zuchao Zhu ◽  
Yu Li
Keyword(s):  
Large Eddy Simulation ◽  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Fluctuation ◽  
Low Frequency ◽  
Pump Impeller ◽  
Eddy Simulation ◽  
Inlet Flow Rate ◽  
Large Eddy ◽  
Centrifugal Pump Impeller

This paper presents a large eddy simulation of a centrifugal pump impeller during a transient condition. The flow rate is sinusoidal and oscillates between 0.25Qd (Qd indicates design load) and 0.75Qd when the rotating speed is maintained. Research shows that in one period, the inlet flow rate will twice reach 0.5Qd, and among the impeller of one moment is a stall state, but the other is a non-stall state. In the process of flow development, the evolution of low-frequency pressure fluctuation shows an obviously sinusoidal form, whose frequency is insensitive to the monitoring position and equals to that of the flow rate. However, inside the impeller, the phase and amplitude in the stall passages lag behind more and are stronger than that in the non-stall passages. Meanwhile, the strongest region of the high-frequency pressure fluctuation appears in the stall passages at the transient rising stage. The second dominant frequency in stall passages is 2.5 times to that in non-stall passages. In addition, similar to the pressure fluctuation, the evolution of the low-frequency head shows a sinusoidal form, whose phase is lagging behind that by one-third of a period in the inlet flow rate.

scholarly journals A Comparative Assessment of Spalart-Shur Rotation/Curvature Correction in RANS Simulations in a Centrifugal Pump Impeller

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Ran Tao ◽  
Ruofu Xiao ◽  
Wei Yang ◽  
Fujun Wang
Keyword(s):  
Kinetic Energy ◽  
Centrifugal Pump ◽  
Flow Rate ◽  
Comparative Assessment ◽  
Turbulence Kinetic Energy ◽  
Low Flow ◽  
Pump Impeller ◽  
Curvature Correction ◽  
Centrifugal Pump Impeller ◽  
Low Flow Rate

RANS simulation is widely used in the flow prediction of centrifugal pumps. Influenced by impeller rotation and streamline curvature, the eddy viscosity models with turbulence isotropy assumption are not accurate enough. In this study, Spalart-Shur rotation/curvature correction was applied on the SSTk-ωturbulence model. The comparative assessment of the correction was proceeded in the simulations of a centrifugal pump impeller. CFD results were compared with existing PIV and LDV data under the design and low flow rate off-design conditions. Results show the improvements of the simulation especially in the situation that turbulence strongly produced due to undesirable flow structures. Under the design condition, more reasonable turbulence kinetic energy contour was captured after correction. Under the low flow rate off-design condition, the prediction of turbulence kinetic energy and velocity distributions became much more accurate when using the corrected model. So, the rotation/curvature correction was proved effective in this study. And, it is also proved acceptable and recommended to use in the engineering simulations of centrifugal pump impellers.

Influences of Impeller Diameter and Diffuser Blades on Air-Water Two-Phase Flow Performance of Centrifugal Pump

2005 ◽  
Author(s):  
Naoki Matsushita ◽  
Akinori Furukawa ◽  
Kusuo Okuma ◽  
Satoshi Watanabe
Keyword(s):  
Centrifugal Pump ◽  
Water Flow ◽  
Flow Rate ◽  
Rotational Speed ◽  
Flow Condition ◽  
High Performance ◽  
Two Phase Flow ◽  
Water Flow Rate ◽  
Phase Flow ◽  
Two Phase

A tandem arrangement of double rotating cascades and single diffuser cascade, proposed as a centrifugal pump with high performance in air-water two-phase flow condition, yields lower head due to the smallness of the impeller outlet in comparison with a impeller with large outlet diameter and no diffuser. Influences of impeller diameter change and installation of diffuser blades on two-phase flow performance were experimentally investigated under the case of the same volute casing. As the result, the similarity law of the diameter of impeller having the similar blade geometry and the rotational speed is satisfied even in two-phase flow condition. Comparing pump performances between a large impeller without diffuser blades and a small one with diffuser blades, higher two-phase flow performance is obtained by controlling the rotational speed of a small impeller with diffuser blades in the range of small water flow rates, while a large impeller with no diffuser gives high performance in the range of high water flow rate and small air flow rate.

Performance Enhancement by Dynamic Valve Timing of a Multistage Vacuum Micropump

2010 ◽  
Author(s):  
Karthik Kumar ◽  
Luis P. Bernal ◽  
Khalil Najafi
Keyword(s):  
Steady State ◽  
Flow Rate ◽  
Pressure Difference ◽  
Performance Enhancement ◽  
High Vacuum ◽  
Operating Pressure ◽  
Transient Operation ◽  
Valve Timing ◽  
Steady State Operation ◽  
Valve Leakage

This paper presents the results of a theoretical analysis of dynamic valve timing on the performance of a multistage peristaltic vacuum micropump. Prior work has shown that for optimum steady state performance a fixed valve timing which depends on the operating pressure can be found. However, the use of a fixed valve timing could hinder performance for transient operation when the pump is evacuating a fixed volume. At the beginning of the transient the pump operates at low pressure difference and a large flow rate would be desirable. As the pump reaches high vacuum the pressure difference is large and the flow rate is necessarily small. Astle and coworkers1–3 have shown using a reduced order model that for steady state operation short valve open time results in lower inlet pressure and flow-rate and conversely. Here we extend the model of Astle and coworkers to include transient operation, multiple coupled stages and non-ideal leaky valves, and show that dynamic valve timing (DVT) reduces the transient duration by 30% compared to high vacuum pressure valve timing. The results also show a significant reduction in resonant frequency of the pump at low pressures, and quantify the effect of valve leakage.

The Response of a Centrifugal Pump to Fluctuating Rotational Speed

1995 ◽  
Vol 117 (3) ◽  
pp. 479-484 ◽  
Author(s):  
H. Tsukamoto ◽  
H. Yoneda ◽  
K. Sagara
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Dynamic Characteristics ◽  
Rotational Speed ◽  
Total Pressure ◽  
Flow Analysis ◽  
Pressure Rise ◽  
Singularity Method ◽  
Measured Flow ◽  
Unsteady Characteristics

A theoretical and experimental study has been made on the dynamic characteristics of a centrifugal pump subject to sinusoidal changes in rotational speed. Time-dependent rotational speed, flow-rate, and total pressure rise are measured for a variety of amplitude and frequency of the fluctuating rotational speed. Measured flow-rate as well as total pressure rise is compared with the quasi-steady ones. Unsteady flow analysis is made for a two-dimensional circular cascade by use of the singularity method. The calculated frequency characteristics are compared with the corresponding experimental ones. The deviation of unsteady characteristics from quasi-steady ones is evident, and the numerical results agree qualitatively with the measured ones. It was found that with the increased frequency of rotational speed fluctuations the dynamic characteristics deviate remarkably from quasi-steady ones. Moreover, a criterion for the assumption of quasi-steady change is presented.

scholarly journals Effects of Flow Rate and Viscosity on Slip Factor of Centrifugal Pump Handling Viscous Oils

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Wen-Guang Li
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Tangential Velocity ◽  
Low Flow ◽  
Liquid Viscosity ◽  
Blade Angle ◽  
Pump Impeller ◽  
Slip Factor ◽  
Hydraulic Design ◽  
Impeller Outlet

Slip factor is an important parameter in the hydraulic design of centrifugal pump impeller for handling viscous oils. How to extract the factor from CFD computational results and how flow rate and liquid viscosity to affect it remain unclear. In the present paper, the flip factor was estimated by means of two approaches: one is from the velocity triangles at the impeller outlet and the other is due to the impeller theoretical head of 3D turbulent viscous fluid. The velocity of water and viscous oils in the impeller and volute computed by CFD was validated with LDV measurements at the best efficiency point. The effect of exit blade angle on slip factor was clarified. It was shown that the two approaches result into two different slip factors. The factors are significantly dependent of flow rate; however, the liquid viscosity seems to take less effect on them. Volute is responsible for reduction in tangential velocity of liquid at the outlet of impeller at low flow rates. The slip factor of impeller with large exit blade angle is not sensitive to flow rate.

Effects of Near-Wall Vortices on Wall Shear Stress in a Centrifugal Pump Impeller

2021 ◽  
Vol 16 ◽  
pp. 37-47
Author(s):  
Salman Shahid ◽  
Abdul Qader Hasan ◽  
Sharul Sham Dol ◽  
Mohamed S. Gadala ◽  
Mohd Shiraz Aris
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Head ◽  
Research Paper ◽  
Shear Stresses ◽  
Pump Impeller ◽  
Wall Shear ◽  
Pump Pressure ◽  
Centrifugal Pump Impeller ◽  
Near Wall

Boundary layer separation and vortex formation cause unappealing deterioration of pump pressure head. The purpose of this research paper is to correlate formation of vortices with near-wall shear stresses resulting in a loss of pump pressure head. This phenomenon is observed at the centrifugal pump impeller tip at various flow rates and impeller rotational velocities through CFD (Computational Fluid Dynamic) analysis. This research paper investigates internal flow in a shrouded centrifugal impeller that is modelled under design flow rate conditions using ANSYS Fluent as its simulation bases solving built-in Navier-Stokes equation, and 𝑘 − 𝜔 SST turbulence model under steady conditions. Numerical results revealed an increase in wall shear stresses with increasing flow rate ranging from 314.2 Pa to 595.60 Pa at increments that pulsate per flow rate. Flow characteristics, such as evolution of vortices and flow turbulence enhance wall shear stresses increasing the wall skin-friction remarkably leading towards a loss in pressure head. This paper analyzes the vortices and turbulence in flow structures with regards to their influence upon the impeller performance.

High-Efficiency Design Technique of a Single-Channel Submersible Pump Impeller for Waste Treatment

2015 ◽  
Author(s):  
Bo-Min Cho ◽  
Joon-Hyung Kim ◽  
Young-Seok Choi ◽  
Kyoung-Yong Lee ◽  
Hye-Young Oh ◽  
...  
Keyword(s):  
Objective Function ◽  
Flow Rate ◽  
High Efficiency ◽  
Stokes Equations ◽  
Single Channel ◽  
Design Flow ◽  
Hydrodynamic Performance ◽  
Submersible Pump ◽  
Maximum Increase ◽  
Pump Impeller

This study presents the hydrodynamic analysis and optimization for a single-channel submersible pump impeller. The numerical analysis involved the use of the shear stress transport turbulence model to solve three-dimensional Reynolds-averaged Navier-Stokes equations. The optimization process was based on a radial basis neural network model and was conducted by considering two design variables to control the area from the inlet to the outlet of the impeller. The hydrodynamic performance of the pump impeller was optimized by selecting the efficiency as the objective function. The objective function was numerically assessed via Latin hypercube sampling at design points selected in the design space, and the optimization yielded a maximum increase in efficiency of approximately 1% in terms of the design flow rate, as compared to the initial design. The performance curve for the efficiency was also improved in the high flow rate region. Further details of the internal flow fields between the reference and optimum designs are also analyzed and discussed in this work.

Effects of flow rate and rotational speed on pressure fluctuations in a double-suction centrifugal pump

Energy ◽  
2019 ◽  
Vol 170 ◽  
pp. 212-227 ◽  
Author(s):  
Zhiyuan Wang ◽  
Zhongdong Qian ◽  
Jie Lu ◽  
Pengfei Wu
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Rotational Speed ◽  
Pressure Fluctuations
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