Primary/Leakage Flow Interaction in a Pump Stage

1999 ◽  
Vol 121 (1) ◽  
pp. 133-138 ◽  
Author(s):  
E. A. Baskharone ◽  
N. J. Wyman
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Leakage Flow ◽  
Computational Domain ◽  
Primary Flow ◽  
Element Analysis ◽  
Impeller Blade ◽  
The Finite Element Analysis ◽  
Pump Stage ◽  
Entire Flow

The finite-element analysis of the combined primary and leakage flow streams in a centrifugal pump is presented. To date, this computational model provides the most accurate “zeroth-order” flow field for rotordynamic calculations, short of analyzing the entire flow field on a fully three-dimensional basis. In formulating the problem, the shaft work is modeled via the angular momentum it imparts to the primary flow stream across the impeller blade region. In casting the boundary conditions, special attention is paid to the multi-connectivity of the newly-contoured computational domain in such a way to avoid over-specification of the problem. The analysis is applied to a typical pump stage with a face seal being part of the leakage passage. The numerical results are then compared to the outcome of the existing lower-order analysis where the impeller subdomain was totally extracted.

Flow Induced Stresses in a Francis Turbine Runner Using Computer-Based Design Tools

2009 ◽  
Author(s):  
Jose´ Manuel Franco-Nava ◽  
Oscar Dorantes-Go´mez ◽  
Erik Rosado-Tamariz ◽  
Jose´ Manuel Ferna´ndez-Da´vila ◽  
Reynaldo Rangel-Espinosa
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Three Dimensional ◽  
Francis Turbine ◽  
Computational Domain ◽  
Element Analysis ◽  
Coordinate Measurement ◽  
The Finite Element Analysis ◽  
Turbine Runner ◽  
Induced Stresses

The stress analysis of the runner due to different loading is one of the most important tools that contribute its structural integrity evaluation. Finite element method has shown to be a strong numerical technique to provide good engineering accuracy. In this paper, the flow induced stresses in a Francis turbine runner is presented by using the finite element analysis. The runner geometry considered within the computational domain was modelled by using a three-dimensional laser triangulation scanner coupled with a portable coordinate measurement system. The runner geometry was generated by a number of 3D sub models, one for each of the main components of the runner, crown, band and a blade. In order to obtain a blade geometry a portable coordinate measurement system based on optical digitalization technology (scanner technology) was used. Because of symmetry, only a section of the runner domain was used for the finite element analysis. The runner was modeled with twenty-node solid elements. Loads due to pressure on the blade were derived from CFD computations for the runner at different power conditions (100%, 85% and 75%) for a medium head hydro power plant. CFD computations were carried out using the Finite Volume Method implement within FINE™/Turbo by NUMECA. The turbulence mathematical model used for the CFD computation was the Sparlart-Allmaras. The mesh of the turbine runner included different computational domains. For the runner blades the computational domain (mesh block) was defined in order to capture the complete blade row. All mesh blocks were structured hexahedral. Centrifugal force based on the rotational speed was considered. Also, a combined type loading analysis was computed including both pressure and centrifugal force. Appropriate boundary conditions were set in order to obtain the results due to the different type of analysis. The number of finite elements included in the FEM model was able to capture the pressure gradients on the blade surfaces obtained from the CFD results, which were investigated by application of a three dimensional Navier-Stoke commercial turbomachinery oriented CFD code. Analysis of the flow through the spiral case and stay vanes was carried out so as to include appropriate flow effects induced by these components and boundary conditions at the inlet of the wicket. A CFD analysis for the wicket and runner was carried out to generate the so called CFD reference solution. The analysis presented in this paper represents an initial characterization in order to increase understanding about combined loads acting on blades and to establish a reference state of stresses further comparison after refurbishments or optimization of the runner blades for a medium head hydroelectric power station.

Finite Element Analysis of Nonuniformity of Tires with Imperfections5

2007 ◽  
Vol 35 (3) ◽  
pp. 226-238 ◽  
Author(s):  
K. M. Jeong ◽  
K. W. Kim ◽  
H. G. Beom ◽  
J. U. Park
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Three Dimensional ◽  
Element Model ◽  
Radial Force ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Dimensional Finite Element ◽  
Force Variation ◽  
Three Dimensional Finite Element

Abstract The effects of variations in stiffness and geometry on the nonuniformity of tires are investigated by using the finite element analysis. In order to evaluate tire uniformity, a three-dimensional finite element model of the tire with imperfections is developed. This paper considers how imperfections, such as variations in stiffness or geometry and run-out, contribute to detrimental effects on tire nonuniformity. It is found that the radial force variation of a tire with imperfections depends strongly on the geometrical variations of the tire.

Modeling and experimental verification on directivity of an electret cell array loudspeaker

2012 ◽  
Vol 24 (3) ◽  
pp. 326-333 ◽  
Author(s):  
Yu-Chi Chen ◽  
Wen-Ching Ko ◽  
Han-Lung Chen ◽  
Hsu-Ching Liao ◽  
Wen-Jong Wu ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Three Dimensional ◽  
Digital Control System ◽  
Analysis Model ◽  
Cell Array ◽  
Element Analysis ◽  
Finite Element Analysis Model ◽  
The Finite Element Analysis ◽  
Directivity Characteristics

We propose a model to give us a method to investigate the characteristic three-dimensional directivity in an arbitrarily configured flexible electret-based loudspeaker. In recent years, novel electret loudspeakers have attracted much interest due to their being lightweight, paper thin, and possessing excellent mid- to high-frequency responses. Increasing or decreasing the directivity of an electret loudspeaker makes it excellent for adoption to many applications, especially for directing sound to a particular area or specific audio location. Herein, we detail a novel electret loudspeaker that possesses various directivities and is based on various structures of spacers instead of having to use multichannel amplifiers and a complicated digital control system. In order to study the directivity of an electret loudspeaker based on an array structure which can be adopted for various applications, the horizontal and vertical polar directivity characteristics as a function of frequency were simulated by a finite-element analysis model. To validate the finite-element analysis model, the beam pattern of the electret loudspeaker was measured in an anechoic room. Both the simulated and experimental results are detailed in this article to validate the various assertions related to the directivity of electret cell-based smart speakers.

Influence of different blade numbers on the performance of “saddle zone” in a mixed flow pump

2021 ◽  
pp. 095765092110460
Author(s):  
Leilei Ji ◽  
Wei Li ◽  
Weidong Shi ◽  
Fei Tian ◽  
Shuo Li ◽  
...  
Keyword(s):  
Flow Field ◽  
Leading Edge ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Mixed Flow ◽  
Impeller Blade ◽  
Flow Angle ◽  
Tip Leakage ◽  
Vorticity Transport ◽  
Flow Pump

In order to study the effect of different numbers of impeller blades on the performance of mixed-flow pump “saddle zone”, the external characteristic test and numerical simulation of mixed-flow pumps with three different impeller blade numbers were carried out. Based on high-precision numerical prediction, the internal flow field and tip leakage flow field of mixed flow pump under design conditions and stall conditions are investigated. By studying the vorticity transport in the stall flow field, the specific location of the high loss area inside the mixed flow pump impeller with different numbers of blades is located. The research results show that the increase in the number of impeller blades improve the pump head and efficiency under design conditions. Compared to the 4-blade impeller, the head and efficiency of the 5-blade impeller are increased by 5.4% and 21.9% respectively. However, the increase in the number of blades also leads to the widening of the “saddle area” of the mixed-flow pump, which leads to the early occurrence of stall and increases the instability of the mixed-flow pump. As the mixed-flow pump enters the stall condition, the inlet of the mixed-flow pump has a spiral swirl structure near the end wall for different blade numbers, but the depth and range of the swirling flow are different due to the change in the number of blades. At the same time, the change in the number of blades also makes the flow angle at 75% span change significantly, but the flow angle at 95% span is not much different because the tip leakage flow recirculates at the leading edge. Through the analysis of the vorticity transport results in the impeller with different numbers of blades, it is found that the reasons for the increase in the values of the vorticity transport in the stall condition are mainly impacted by the swirl flow at the impeller inlet, the tip leakage flow at the leading edge and the increased unsteady flow structures.

scholarly journals Evaluation of the Effects of the Chincup Appliance on the Craniofacial Structures by the Finite Element Analysis

2017 ◽  
Vol 7 ◽  
pp. 219-223
Author(s):  
Beril Demir Karamanli ◽  
Hülya Kılıçoğlu ◽  
Armagan Fatih Karamanli
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Fe Model ◽  
Analysis Method ◽  
Class Iii ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Clinical Changes

Aims The aim of this study is to evaluate the effects of the chincup appliance used in the treatment of Class III malocclusions, not only on the mandible or temporomandibular joint (TMJ) but also on all the craniofacial structures. Materials and Methods Chincup simulation was performed on a three-dimensional finite element (FE) model. 1000 g (500 g per side) force was applied in the direction of chin-condyle head. Nonlinear FE analysis was used as the numerical analysis method. Results By the application of chincup, stresses were distributed not only on TMJ or mandible but also on the circummaxillary sutures and other craniofacial structures. Conclusions Clinical changes obtained by chincup treatment in Class III malocclusions are not limited by only mandible. It was seen that also further structures were affected.

Design and Analysis of a Tow Truck’s Lifting Organ

2014 ◽  
Vol 644-650 ◽  
pp. 137-141
Author(s):  
Guo Sheng Zhang ◽  
Wei Zhou ◽  
Ye Chen ◽  
Jian Qiang Gong
Keyword(s):  
Mechanical Design ◽  
Three Dimensional ◽  
Operation Condition ◽  
Element Analysis ◽  
Vehicle Accidents ◽  
Local Strength ◽  
The Finite Element Analysis ◽  
Design Software ◽  
Mechanics Characteristics ◽  
Game Type

According to the super large or heavy vehicle accidents existing wrecker cannot complete the wrecker rescue mission independent problems, puts forward the design of a practical game type crane wrecker. The hoisting mechanism as the research object, the traditional mechanical method is designed and calculated, then the three-dimensional entity model using 3D mechanical design software Solidworks, and imported into the finite element analysis software ANSYS to analyze the static mechanics characteristics of the structure, to improve the local strength of short position. On this basis, a lifting test vehicle prototype, rated load operation and overload operation condition test, and measure its subsidence. With the analysis of the experiment results, show that the design truck lifting organ can meet the demand of the technology.

Simulation of Nine-Spacer Nozzle’s Flow Field of Al Roll-Casting Using Coupled Fluid-Thermal Finite Element Analysis

2010 ◽  
Vol 159 ◽  
pp. 697-702
Author(s):  
Ying Zhou ◽  
Ya Xi Tan
Keyword(s):  
Thermal Analysis ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Flow Field ◽  
Three Dimensional ◽  
Fem Simulation ◽  
Cooling Capacity ◽  
Element Analysis ◽  
Roll Casting ◽  
Element Simulation

A three-dimensional coupled fluid-thermal finite element simulation model has been developed to provide analyzing distribution of velocity and temperature of nine-spacer nozzle by using FEM simulation of FLOTRAN module in ANSYS 6.0. To explore fluid-thermal analysis of the flow fields of nine-spacer nozzle of aluminum roll-casting, stricter analysis of postprocessing result was conducted by MATLAB. It was concluded that flow field of nine-spacer nozzle was able to match cooling capacity of cast rollers, but nine-spacer nozzle’s geometric flaw didn’t suit for working in the case of speed increasing of the drawing-sheet and thickness reducing of the aluminium sheet during roll casting.

Dielectrophoretic Mixing With Novel Electrode Geometry

2009 ◽  
Author(s):  
G. Naga Siva Kumar ◽  
Sushanta K. Mitra ◽  
Subir Bhattacharjee
Keyword(s):  
Electric Field ◽  
Cell Activation ◽  
Colloidal Particles ◽  
Colloidal Suspension ◽  
Three Dimensional ◽  
Colloidal Suspensions ◽  
Navier Stokes ◽  
Mixing Efficiency ◽  
Computational Domain ◽  
Element Analysis

Electrokinetic mixing of analytes at micro-scale is important in several biochemical applications like cell activation, DNA hybridization, protein folding, immunoassays and enzyme reactions. This paper deals with the modeling and numerical simulation of micromixing of two different types of colloidal suspensions based on principle of dielectrophoresis (DEP). A mathematical model is developed based on Laplace, Navier-Stokes, and convection-diffusion-migration equations to calculate electric field, velocity, and concentration distributions, respectively. Mixing of two colloidal suspensions is simulated in a three-dimensional computational domain using finite element analysis considering dielectrophoretic, gravitational and convective (advective)–diffusive forces. Phase shifted AC signal is applied to the alternating electrodes for achieving the mixing of two different colloidal suspensions. The results indicate that the electric field and DEP forces are maximum at the edges of the electrodes and become minimum elsewhere. As compared to curved edges, straight edges of electrodes have lower electric field and DEP forces. The results also indicate that DEP force decays exponentially along the height of the channel. The effect of DEP forces on the concentration profile is studied. It is observed that, the concentration of colloidal particles at the electrodes edges is very less compared to elsewhere. Mixing of two colloidal suspensions due to diffusion is observed at the interface of the two suspensions. The improvement in mixing after applying the repulsive DEP forces on the colloidal suspension is observed. Most of the mixing takes place across the slant edges of the triangular electrodes. The effect of electrode pairs and the mixing length on degree of mixing efficiency are also observed.

Experimental and Numerical Investigation of the Unsteady Leakage Flow Through the Rotor Tip Labyrinth of a 1.5-Stage Axial Turbine

2005 ◽  
Author(s):  
K. Wolter ◽  
A. Giboni ◽  
P. Peters ◽  
J. R. Menter ◽  
H. Pfost
Keyword(s):  
Flow Field ◽  
Flow Direction ◽  
Three Dimensional ◽  
Calculated Data ◽  
Leading Edge ◽  
Numerical Data ◽  
Potential Effect ◽  
Main Flow ◽  
Leakage Flow ◽  
Axial Turbine

This paper presents the results of unsteady probe measurements and numerical flow calculations in a 1.5-stage low speed axial turbine with a straight labyrinth seal on a rotor shroud. The unsteady development of the leakage flow in the three cavities is described and analysed in detail. For the investigation of the leakage flow detailed time-accurate measurements of the three-dimensional flow field were carried out in five measurement planes from casing to the rotor shroud over more than one pitch. These measurements were carried out with a miniature pneumatic five-hole probe and miniature triple hot-wire probes. Both probes have a spherical head for better adjustment in flow direction. The high resolution of 330 measurement points in each of the five measurement planes represents the flow field in great detail. The unsteady experimental data was compared with the results of the unsteady numerical simulation of the turbine flow, calculated by the 3D-Navier-Stokes Solver CFX-TASCflow. The calculated data correspond well with the experimental results and allow a detailed analysis of the flow in the cavities of the labyrinth. As demonstrated in this paper the investigations show that the leakage flow at the inlet ant outlet of the labyrinth is strongly influenced by the different positions of the rotor to the stator. The unsteady experimental and numerical data indicates intensive effects of the leakage flow caused and influenced by the trailing edge of the first stator and the potential effect of the rotor leading edge. An intensive vortex develops depending on the rotor position in the first cavity. This vortex is also influenced by a small corner vortex above the axial inlet gap of the labyrinth. After the fins this unsteady influence of the leakage flow decreases and below the jet a large vortex moves in circumferential direction. The intensity of this circulation vortex is reduced at the end of the last cavity due to the interaction with the main flow and the flow direction out of the labyrinth. Therefore the unsteady behaviour of the leakage flow grows up, which is also caused by its uneven entry into the main flow.

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