Fundamental Analysis on Rotor-Stator Interaction in a Diffuser Pump by Vortex Method

2001 ◽  
Vol 123 (4) ◽  
pp. 737-747 ◽  
Author(s):  
H. Wang ◽  
H. Tsukamoto
Keyword(s):  
Numerical Solutions ◽  
Pressure Fluctuations ◽  
Vortex Method ◽  
Solid Boundary ◽  
Vaned Diffuser ◽  
Unsteady Pressure ◽  
Pumping System ◽  
Rotor Stator Interaction ◽  
The Stability ◽  
Stability And Accuracy

A two-dimensional unsteady flow was calculated within a whole stage of a diffuser pump to investigate pressure fluctuations due to the interaction between impeller and diffuser vanes by using the vortex method, in which vortices shedding from solid boundary were determined by the basic governing equation. The Petrov-Galerkin Method was applied to yield the solutions that satisfy the boundary conditions in an integral sense, and it improved the stability and accuracy of the numerical solutions greatly. A new scheme was also proposed to improve the unsteady pressure evaluation by a boundary integration method in the rotor-stator interaction problem. Moreover, for a more realistic prediction of the pressure fluctuations, the inlet flow was supposed to change with time so that pumping system may balance. The calculated time-varying flow rate, total hydraulic head rise and pressure fluctuations in the vaned diffuser passage, were compared with the measured and calculated ones by other methods. Calculated unsteady pressure fluctuations in the vaned diffuser passage showed good agreement with the experimental data and the CFD calculated ones.

Unsteady Hydrodynamic Forces due to Rotor-Stator Interaction on a Diffuser Pump With Identical Number of Vanes on the Impeller and Diffuser

2005 ◽  
Vol 127 (4) ◽  
pp. 743-751 ◽  
Author(s):  
M. Zhang ◽  
H. Tsukamoto
Keyword(s):  
Computational Study ◽  
Pressure Fluctuations ◽  
Vortex Method ◽  
Hydrodynamic Forces ◽  
Pump Impeller ◽  
Vaned Diffuser ◽  
Fluid Forces ◽  
Rotor Stator Interaction ◽  
Identical Number ◽  
Good Agreement

Experimental and computational study was developed for unsteady hydrodynamic forces on a diffuser pump impeller excited by the interaction between the impeller and the vaned diffuser with the same number of vanes as impeller. Unsteady flow calculations are made using commercially available CFD software, CFX-TASCflow, as well as the two-dimensional vortex method. Calculated pressure and fluid forces on the impeller show good agreement with measured ones. It has been demonstrated that the fluid forces on the impeller with the same number of vanes as the vaned diffuser are smaller compared with other combinations of vane numbers. However, the pressure fluctuations are found to be greater than other cases.

scholarly journals Numerical Investigation of Periodically Unsteady Pressure Field in a High Power Centrifugal Diffuser Pump

2014 ◽  
Vol 6 ◽  
pp. 159380 ◽  
Author(s):  
Ji Pei ◽  
Wenjie Wang ◽  
Shouqi Yuan ◽  
Jieyun Mao
Keyword(s):  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
Heat Removal ◽  
Centrifugal Pumps ◽  
Unsteady Pressure ◽  
Fluctuation Intensity ◽  
Rotor Stator Interaction ◽  
Operational Flow ◽  
Downstream Flow ◽  
Pressure Characteristics

Pressure fluctuations are the main factors that can give rise to reliability problems in centrifugal pumps. The periodically unsteady pressure characteristics caused by rotor-stator interaction have been investigated by CFD calculation in a residual heat removal pump. Side chamber flow effect is also considered for the simulation to accurately predict the flow in whole flow passage. The pressure fluctuation results in time and frequency domains were considered for several typical monitoring points in impeller and diffuser channels. In addition, the pressure fluctuation intensity coefficient (PFIC) based on standard deviation was defined on each grid node for entire space and impeller revolution period. The results show that strong pressure fluctuation intensity can be found in the gap between impeller and diffuser. As a source, the fluctuation can spread to the upstream and downstream flow channels as well as the side chamber channels. Meanwhile, strong pressure fluctuation intensity can be found in the discharge tube of the circular casing. In addition, the obvious influence of operational flow rate on the PFIC distribution can be found. The analysis indicates that the pressure fluctuations in the aspects of both frequency and intensity can be used to comprehensively evaluate the unsteady pressure characteristics in centrifugal pumps.

STABILITY AND ACCURACY OF LATTICE BOLTZMANN SCHEMES FOR ANISOTROPIC ADVECTION-DIFFUSION EQUATIONS

2009 ◽  
Vol 20 (04) ◽  
pp. 633-650 ◽  
Author(s):  
SHINSUKE SUGA
Keyword(s):  
Lattice Boltzmann ◽  
Numerical Experiments ◽  
Numerical Solutions ◽  
Velocity Model ◽  
Diffusion Equations ◽  
Benchmark Problems ◽  
Relaxation Parameters ◽  
Advection Diffusion ◽  
The Stability ◽  
Stability And Accuracy

The stability of the numerical schemes for anisotropic advection-diffusion equations derived from the lattice Boltzmann equation with the D2Q4 particle velocity model is analyzed through eigenvalue analysis of the amplification matrices of the scheme. Accuracy of the schemes is investigated by solving benchmark problems, and the LBM scheme is compared with traditional implicit schemes. Numerical experiments demonstrate that the LBM scheme produces stable numerical solutions close to the analytical solutions when the values of the relaxation parameters in x and y directions are greater than 1.9 and the Courant numbers satisfy the stability condition. Furthermore, the numerical solutions produced by the LBM scheme are more accurate than those of the Crank–Nicolson finite difference scheme for the case where the Courant numbers are set to be values close to the upper bound of the stability region of the scheme.

scholarly journals Constructions of the soliton solutions to the good Boussinesq equation

2020 ◽  
Vol 2020 (1) ◽  
Author(s):  
Mohammed Bakheet Almatrafi ◽  
Abdulghani Ragaa Alharbi ◽  
Cemil Tunç
Keyword(s):  
Traveling Wave ◽  
Numerical Solutions ◽  
Numerical Technique ◽  
Nonlinear Partial Differential Equations ◽  
Soliton Solutions ◽  
Traveling Wave Solutions ◽  
Solution Stability ◽  
Exact Results ◽  
The Stability ◽  
Stability And Accuracy

Abstract The principal objective of the present paper is to manifest the exact traveling wave and numerical solutions of the good Boussinesq (GB) equation by employing He’s semiinverse process and moving mesh approaches. We present the achieved exact results in the form of hyperbolic trigonometric functions. We test the stability of the exact results. We discretize the GB equation using the finite-difference method. We also investigate the accuracy and stability of the used numerical scheme. We sketch some 2D and 3D surfaces for some recorded results. We theoretically and graphically report numerical comparisons with exact traveling wave solutions. We measure the $L_{2}$ L 2  error to show the accuracy of the used numerical technique. We can conclude that the novel techniques deliver improved solution stability and accuracy. They are reliable and effective in extracting some new soliton solutions for some nonlinear partial differential equations (NLPDEs).

Numerical Analysis of Unsteady Hydrodynamic Forces on a Diffuser Pump Impeller Due to Rotor-Stator Interaction

2002 ◽  
Author(s):  
M. Zhang ◽  
H. Wang ◽  
H. Tsukamoto
Keyword(s):  
Numerical Analysis ◽  
Pressure Fluctuations ◽  
Vortex Method ◽  
Hydrodynamic Forces ◽  
Local Pressure ◽  
Pump Impeller ◽  
Fluid Forces ◽  
Rotor Stator Interaction ◽  
Pipe Systems

The 2-D vortex method and the commercially available CFD software are applied to calculate unsteady hydrodynamic forces on a diffuser pump impeller and the pressure fluctuations caused by the interaction between the impeller and the diffuser vanes. Calculated pressure and fluid forces on the impeller are compared with measured ones. The numerical analysis yields fairly accurate predictions of the fluid forces and the pressure fluctuations in diffuser passages and the pipe systems. It has been demonstrated that the fluid forces caused by the interaction between the rotor and stator vanes are small when the number of vanes on impeller and diffuser is identical. In this case, however, the local pressure fluctuations are larger in diffuser passages and the pipe systems.

Impeller-Diffuser Interaction in Centrifugal Compressors

2012 ◽  
Author(s):  
Chris Robinson ◽  
Michael Casey ◽  
Brad Hutchinson ◽  
Robin Steed
Keyword(s):  
Pressure Ratio ◽  
Pressure Fluctuations ◽  
Peak Efficiency ◽  
Vaned Diffuser ◽  
High Pressure Ratio ◽  
Steady Stage ◽  
Rotor Stator Interaction ◽  
Design Speed ◽  
Steady Simulation ◽  
Cfd Analyses

This paper reports several CFD analyses of a centrifugal compressor stage with a vaned diffuser at high pressure ratio using different techniques to model the rotor-stator interaction. A conventional steady stage calculation with a mixing-plane type interface between the rotor and stator was used as a baseline. This simulation gave excellent agreement with the measured performance characteristics at design speed, demonstrating the ability of the particular steady simulation used to capture the essential features of the blockage interaction between the components. A full annulus simulation using a transient rotor-stator interaction (TRS) method was then used at the peak efficiency point to obtain a fully unsteady reference solution, and this predicted a small increase in peak efficiency. Finally, a computationally less expensive unsteady calculation using a Time Transformation (TT) method was carried out. This gave similar results to the fully transient calculation suggesting that this is an acceptable approach to estimate unsteady blade loading from the interaction. The impeller diffuser spacing was then reduced from 15 to 7% of the impeller tip radius using the more affordable TT approach. This identified an increase in efficiency of 1% and predicted unsteady pressure fluctuations in the impeller which were 116% higher with the closely spaced diffuser.

Effects of Lean Mode of Blade Trailing Edge On Pressure Fluctuation Characteristics of a Vertical Centrifugal Pump with Vaned Diffuser

2021 ◽  
Author(s):  
Yongshun Zeng ◽  
Zhifeng Yao ◽  
Ran Tao ◽  
Weichao Liu ◽  
Ruofu Xiao
Keyword(s):  
Centrifugal Pump ◽  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
Hydraulic Performance ◽  
Wake Flow ◽  
Long Distance ◽  
Trailing Edge ◽  
Excessive Pressure ◽  
Vaned Diffuser ◽  
Rotor Stator Interaction

Abstract A vertical centrifugal pump with a vaned diffuser is very attractive in the field of long-distance water supply. Excessive pressure fluctuations in the vaneless region due to rotor stator interaction (RSI) need careful evaluation. In the present investigation, the hydraulic performance and pressure fluctuation characteristics of a vertical centrifugal pump with three different lean modes of the blade trailing edge were quantitatively analyzed by comparison experiments, using the same test rig. Results showed that the pressure fluctuation level was the highest in the vaneless region, closest to the volute tongue, and increased as the flowrate deviated from the design flowrate. The lean mode of the blade trailing edge was found to have a slight influence on hydraulic performance, and the relative deviation of experimental specific speeds with three different lean modes was within 6%. The influence of the lean mode of the blade trailing edge on the pressure fluctuation level was experimentally verified for the first time. In particular, the flowrate-averaged peak-to-peak value of pressure fluctuation with the positive lean mode (PLM) was 62% of the corresponding value with the zero lean mode (ZLM), while no significant improvement was observed for the negative lean mode (NLM). The flow mechanism behind this may be explained as a weakening of the jet-wake flow pattern with PLM.

Sign in / Sign up

Export Citation Format

Share Document