scholarly journals Clocking effect of outlet RGVs on hydrodynamic characteristics in a centrifugal pump with an inlet inducer by CFD method

2021 ◽  
Vol 15 (1) ◽  
pp. 222-235
Author(s):  
Xiang-Yuan Zhang ◽  
Chen-Xing Jiang ◽  
Shen Lv ◽  
Xi Wang ◽  
Tao Yu ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Hydrodynamic Characteristics ◽  
Cfd Method

Flow Field Theoretical Optimization and Experimental Verification of Centrifugal Pump

2014 ◽  
Vol 716-717 ◽  
pp. 627-630 ◽  
Author(s):  
Yuan Sheng Lin ◽  
Quan Zhang ◽  
Lu Dai ◽  
Xu Hu
Keyword(s):  
Flow Field ◽  
Centrifugal Pump ◽  
Pressure Pulsation ◽  
Vibration Level ◽  
Noise Emission ◽  
Vibration Responses ◽  
Exciting Forces ◽  
Field Excitation ◽  
Cfd Method ◽  
Base Structure

Researches on vibration of centrifugal pump induced by fluid exciting forces are significant for reducing equipment faults, which are caused by the vibration transferring from the base, and noise emission of shells which connected with the base. Fluid exciting forces are the main vibration sources in centrifugal pump systems. The vibration of impellers is generated by fluid exciting forces, and transferred to mechanical systems through pump shell and shaft bearings. By optimizing of inner flow filed of centrifugal pump, not only the fluid exciting forces can be reduced, but also the vibration level of the pump can be improved. In this paper, based on reducing noise and isolating vibration, the inner flow field of the centrifugal pump was emulated by CFD method. The flow field was optimized by controlling the impellers cutting process. The optimizing results were shown by comparing the pressure pulsation of the optimized flow field with those of the original flow field. The improvement of optimization was verification by measuring the vibration responses of the centrifugal pump base structure. The experimental results shows that: the level of flow field excitation and the pressure pulsation of flow field under the blade frequencies and multiplication frequencies are declined to some degree by cutting impellers; the vibration responses of pump base decreased 4.5 dB after cutting impeller.

Modeling Viscous Oil Cavitating Flow in a Centrifugal Pump

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Wen-Guang Li
Keyword(s):  
Centrifugal Pump ◽  
Volume Ratio ◽  
Cavitating Flow ◽  
Liquid Volume ◽  
Cavitation Model ◽  
Gas Concentration ◽  
Noncondensable Gas ◽  
Cavitation Performance ◽  
Pump Head ◽  
Cfd Method

Properly modeling cavitating flow in a centrifugal pump is a very important issue for prediction of cavitation performance in pump hydraulic design optimization and application. As a first trial, the issue is explored by using computational fluid dynamics (CFD) method plus the full cavitation model herein. To secure a smoothed head-net positive suction head available (NPSHa) curve, several critical techniques are adopted. The cavitation model is validated against the experimental data in literature. The predicted net positive suction head required (NPSHr) correction factor for viscosity oils is compared with the existing measured data and empirical correlation curve, and the factor is correlated to impeller Reynolds number quantitatively. A useful relation between the pump head coefficient and vapor plus noncondensable gas-to-liquid volume ratio in the impeller is obtained. Vapor and noncondensable gas concentration profiles are illustrated in the impeller, and a “pseudocavitation” effect is confirmed as NPSHa is reduced. The effects of exit blade angle on NPSHr are presented, and the contributions of liquid viscosity and noncondensable gas concentration to the increase of NPSHr at a higher viscosity are identified.

scholarly journals Modeling and Efficiency Prediction of Aeroengine Centrifugal Pump Integrated Loss Model Based on One-Dimensional Flow

2018 ◽  
Vol 36 (5) ◽  
pp. 807-815
Author(s):  
Jiangfeng Fu ◽  
Huacong Li ◽  
Ding Fan ◽  
Wenbo Shen ◽  
Xianwei Liu
Keyword(s):  
Experimental Data ◽  
Centrifugal Pump ◽  
Relative Error ◽  
Performance Prediction ◽  
Design Parameters ◽  
Hydraulic Loss ◽  
Pump Efficiency ◽  
Centrifugal Pumps ◽  
Loss Model ◽  
Cfd Method

This paper was presented a method of integrated loss model by considering all kinds of loss type in centrifugal pumps. The geometric structure and loss mechanism of the flow parts in the centrifugal pump were analyzed, such as suction chamber, impeller, vaneless diffuser chamber, volute type water collecting chamber and outlet diffusion section. The hydraulic loss model, volume loss model, friction loss and mechanical loss model of centrifugal pump were established respectively by combining the flow theory. Finally, an integrated loss model of centrifugal pump was constructed, which can establish the relationship between the 12 main design parameters and pump efficiency of the centrifugal pump. Then the performance prediction of an aeroengine fuel centrifugal pump was carried out based on the loss model, and the loss model predictions were compared with the experimental data and CFD simulation performance prediction data. Simulation results show that:The efficiency predicted value relative error of centrifugal pump is less than 2.8% between the loss model and the experimental data. The computational efficiency of CFD is less than 4.4% compared with the experimental data in the design condition. The relative error is about 1.6% between the CFD method and the loss model which shows that the loss model predicts efficiency accuracy is better than the CFD method. It shows that this method can be used to predict the efficiency performance of centrifugal pump under design process.

scholarly journals Development and Numerical Performance Analysis of a Pump Directly Driven by a Hydrokinetic Turbine

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4264
Author(s):  
Daqing Zhou ◽  
Huixiang Chen ◽  
Yuan Zheng ◽  
Kan Kan ◽  
An Yu ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Degrees Of Freedom ◽  
Draft Tube ◽  
Model Tests ◽  
Cross Sectional ◽  
Practical Applications ◽  
Plain Area ◽  
Pump Head ◽  
Cfd Method ◽  
River Current

Marine and hydrokinetics (MHK) represent an emerging industry with hundreds of potentially viable technologies, such as potential extractable energy from plain area rivers where the water level differences are very small and the traditional water turbine pump (WTP) cannot be used. A suitable WTP, composed of a tubular turbine directly driving a centrifugal pump, was designed and developed based on computational fluid dynamics (CFD) and model tests. Two general design schemes of such river-current (RC)-driven WTP are presented here, obtaining the desired operating parameters of discharge and pump head. A CFD analysis of Scheme B, which employs a radial outlet, allowing additional degrees of freedom for the dimensions of the centrifugal pump, was carried out and verified experimentally by model tests. The minimum deviation of pump head is within ±5%, and the trend of other working conditions is consistent, so the results of the numerical simulation and model tests show good agreement, demonstrating the feasibility of the CFD method for practical applications. Then, using the CFD method, the optimum rotational speed for the turbine was determined, and the turbine draft tube was improved further. With a turbine runner diameter of 0.5 m, the results show best performance at n = 350 r/min. The straight conical draft tube was changed to an elbow draft tube with multiple exits. Additionally, four different cross-sectional shapes were designed for the pump volute, and their effects on the performance of the WTP were analyzed. Finally, the round shape was selected, because of its best performance. The turbine unit has the highest efficiency of 81.2%, at an inlet velocity v = 2.4 m/s, while the pump exhibits the best efficiency of 90.2% at the design discharge and head of 30 l/s and 4.45 m respectively. Overall, the RC-driven WTP makes good use of the kinetic energy of the river current as a power source, solving the inapplicability of traditional WTP in plain areas.

scholarly journals Numerical Investigation on the Mechanism of Double-Volute Balancing Radial Hydraulic Force on the Centrifugal Pump

Processes ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 689
Author(s):  
Yuan ◽  
Yuan ◽  
Tang
Keyword(s):  
Centrifugal Pump ◽  
Cross Sections ◽  
Performance Test ◽  
Flow Characteristics ◽  
Radial Force ◽  
Transient Pressure ◽  
Force Magnitude ◽  
Hydraulic Force ◽  
Pump Head ◽  
Cfd Method

Double-volute is an effective technique to reduce radial hydraulic force on the centrifugal pump and thereby mitigate the pump-casing vibration induced by unsteady flow characteristics. The mechanism of the double-volute structure balancing radial force on the impeller and volute was investigated on the basis of volute cross-sections by using Computational Fluid Dynamics (CFD) method. The tested performances and simulated inner-flow characteristics of two pumps with single-volute and double-volute were compared in this paper. The performance-test results verify the veracity of CFD method and illustrate that double-volute pump has some losses in terms of pump head and operation efficiency. The numerical simulations reveal that double-volute pump has smaller radial-force magnitude than single-volute pump on the abnormal conditions. Steady pressure field and transient pressure variations of pumps were explored to account for radial-force characteristics of double-volute pump. Compared with the single-volute structure, obvious pressure increases were found in the upper chamber (single part) of the double-volute, while the static pressure decreased in the lower chamber (double chambers). This situation reduces the pressure difference between two volute cross-sections in the collinear radial direction, resulting in smaller radial hydraulic force. Moreover, the transient simulations present the same phenomenon. The radial-forces distribute more uniformly in the double-volute pump, which can alleviate some vibrations.

Vortex shedding modes around oscillating non-uniform double heave plates

2020 ◽  
pp. 147509022096691
Author(s):  
Abuzar Abazari ◽  
Mehdi Alvandi ◽  
Mehdi Behzad ◽  
Krish P Thiagarajan
Keyword(s):  
Vortex Shedding ◽  
Harmonic Oscillation ◽  
Added Mass ◽  
Hydrodynamic Performance ◽  
Hydrodynamic Characteristics ◽  
Offshore Platforms ◽  
Vortex Interaction ◽  
Cfd Method ◽  
Vortex Shedding Modes ◽  
Strong Vortex

Multiple co-axial heave plates of uniform geometry are attached to offshore platforms for inducing damping and added mass. These effects generally decrease the magnitude of the dynamic response of the platform under applied environmental excitation forces. When spacing between heave plates is decreased the damping and added mass performance are altered due to their strong vortex interaction. A new non-uniform plate configuration is proposed that may create different hydrodynamic characteristics. The modes of vortex shedding around plate edges in a non-uniform arrangement under forced harmonic oscillation are investigated via the CFD method. Furthermore, a new simplified formula for the total theoretical added mass of a general non-uniform double disk is proposed when it is in the zone which vortex interaction take places. The results show that a non-uniform double disk has better hydrodynamic performance as compared to the uniform double configuration for a given spacing. It is also observed that the mode and direction of the vortex shedding are different for uniform and non-uniform arrangements in a given spacing and KC value.

scholarly journals Simulation of vertical tidal turbine based on OpenFOAM and influence of inlet turbulence

2019 ◽  
Vol 272 ◽  
pp. 01017
Author(s):  
Liu Yun-ya ◽  
Yu-chen Yang ◽  
Ya-wen Yang
Keyword(s):  
Numerical Simulation ◽  
Turbulence Model ◽  
Cfd Simulation ◽  
Vertical Axis ◽  
Simulation Method ◽  
Hydrodynamic Characteristics ◽  
Numerical Simulation Method ◽  
Tidal Turbine ◽  
Cfd Method ◽  
Control Equation

This paper first introduces the basic theory of CFD method, including basic control equations, finite volume method, control equation solving algorithm and turbulence model selection. Second, based on OpenFOAM, an open-source fluid mechanics software, a numerical simulation method of vertical axis tidal turbine was proposed by using k-ω SST turbulence model and PIMPLE algorithm. The hydrodynamic characteristics of the vertical axis turbine were studied, and the calculation results were compared with experiments. The higher consistency proves the feasibility of the numerical simulation method proposed in this paper. Finally, the influence of inlet turbulence on numerical simulation was explored, and a set of effective CFD simulation strategies was concluded, which provided a valuable reference for future CFD simulation and research on vertical axis tidal turbines.

scholarly journals Investigation on Clocking Effect of Diffuser in a Multi-Stage Centrifugal Pump

2021 ◽  
Author(s):  
Tan Ming-Gao ◽  
Sun Xue-Lei ◽  
Wu Xian-Fang ◽  
Liu Hou-Lin
Keyword(s):  
Centrifugal Pump ◽  
Pressure Pulsation ◽  
Rotation Frequency ◽  
Energy Performance ◽  
Test Scheme ◽  
Hydraulic Loss ◽  
Obvious Effect ◽  
Outlet Pressure ◽  
Multi Stage ◽  
Cfd Method

Abstract The clocking effect is an important phenomenon in the multi-stage Rotating machinery. In order to master the rules and mechanism of diffuser clocking effect on the performance of multi-stage centrifugal pump, the orthogonal tests were applied to design the test scheme. The energy performance and outlet pressure pulsation of a multi-stage centrifugal pump with different diffuser clocking positions were synchronously measured. It was found that the diffuser clocking position had little influence on the energy performance, but had an obvious effect on the outlet pressure pulsation. When the diffuser clocking positions were 0°, 30°, 30° and 30° (CL4), the effective value of outlet pressure pulsation and its amplitude at the main frequency (Impeller Rotation Frequency) were decreased the most, approximately 27.2 % and 38.5 % ,respectively. The CFD method was used to simulate the unsteady flow in the pump with the optimal diffuser clocking position (CL4) and without diffuser clocking position (CL1) respectively to reveal the mechanism of diffuser clocking effect. The simulation results showed that the change of diffuser clocking position can improve the inlet and outlet velocity distribution and reduce the area of high turbulent kinetic energy and the number of cores in the outlet flow passage, which is beneficial to the operation stability of the pump. Compared with the CL1, the hydraulic loss in the four diffusers was reduced by 2.43 %, 12.15 %, 11.43 % and 13.19 % respectively under the optimal diffuser clocking scheme (CL4), and the total reduction of hydraulic loss is about 1.11 % of the pump head.

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