Effect of Pitch Chord Ratio and Side Wall Expansion Angle on Flow Through Vane Swirlers

2006 ◽  
Author(s):  
R. Thundil Karuppa Raj ◽  
V. Ganesan
Keyword(s):  
Computational Study ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Side Wall ◽  
Reynolds Stress Model ◽  
Swirl Flow ◽  
Expansion Angle ◽  
Turbulence Effects ◽  
Flow Field Characteristics ◽  
Flow Through

This paper is concerned with the computational study of steady flow through the vane swirlers. Swirl flow field characteristics for various pitch chord ratio (s/c) at swirler mean radius are studied for a 45° vane swirler under both sudden and gradual expansions with side-wall expansion angles of 90° and 45° respectively. In the computational study the geometry and meshing is done using pre-processor GAMBIT. Three-dimensional flow within the geometry and through the swirler has been simulated by solving the appropriate governing equations viz. conservation of mass and momentum using FLUENT code. Turbulence effects are taken care of by the Reynolds stress model and shear stress transport k-ω model for high swirls and standard k-ε model for low and medium swirls. The effect of pitch to chord ratio (s/c) on flow characteristics have been studied. The predicted results are validated with the experimental data available in the literature for s/c ratio of 1. The numerical results of axial velocity profiles downstream of the swirler at various axial planes are found to be in close agreement with the experimental results. It is found that the s/c ratio of 1 provides good turning efficiency.

Numerical and Experimental Investigation of Flow Through Vane Swirlers

2005 ◽  
Author(s):  
R. Thundil Karuppa Raj ◽  
V. Ganesan
Keyword(s):  
Loss Factor ◽  
Computational Study ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Reynolds Stress Model ◽  
Governing Equations ◽  
Three Dimensional Flow ◽  
Turbulence Effects ◽  
Flow Through ◽  
Vane Angle

This paper is concerned with the computational and experimental study of steady flow through vane swirlers for various vane angles from 15° to 60° in steps of 15°. In the computational study the geometry and meshing is done using pre-processor GAMBIT. Three dimensional flow within the geometry and through the swirler has been simulated by solving the appropriate governing equations viz. conservation of mass and momentum using FLUENT code. Turbulence effects are taken care of by the Reynolds stress model for high swirls and standard k-ε model for low swirls. The effects of vane angle on flow characteristics have been studied. A parametric study is done for a 45° vane swirler to investigate the effect of number of vanes. Experimental results of axial velocity profiles downstream of the swirler are found to be in close agreement with the numerical results. The total pressure loss factor, maximum reverse velocity and maximum reverse mass flow for each swirler are determined

Wake Flow of Single and Multiple Yawed Cylinders

2004 ◽  
Vol 126 (5) ◽  
pp. 861-870 ◽  
Author(s):  
A. Thakur ◽  
X. Liu ◽  
J. S. Marshall
Keyword(s):  
Computational Study ◽  
Three Dimensional ◽  
Side Wall ◽  
Wake Flow ◽  
Upstream Region ◽  
Two Dimensional ◽  
Cylinder Wake ◽  
Dimensional Approximation ◽  
The Face ◽  
Drag And Lift

An experimental and computational study is performed of the wake flow behind a single yawed cylinder and a pair of parallel yawed cylinders placed in tandem. The experiments are performed for a yawed cylinder and a pair of yawed cylinders towed in a tank. Laser-induced fluorescence is used for flow visualization and particle-image velocimetry is used for quantitative velocity and vorticity measurement. Computations are performed using a second-order accurate block-structured finite-volume method with periodic boundary conditions along the cylinder axis. Results are applied to assess the applicability of a quasi-two-dimensional approximation, which assumes that the flow field is the same for any slice of the flow over the cylinder cross section. For a single cylinder, it is found that the cylinder wake vortices approach a quasi-two-dimensional state away from the cylinder upstream end for all cases examined (in which the cylinder yaw angle covers the range 0⩽ϕ⩽60°). Within the upstream region, the vortex orientation is found to be influenced by the tank side-wall boundary condition relative to the cylinder. For the case of two parallel yawed cylinders, vortices shed from the upstream cylinder are found to remain nearly quasi-two-dimensional as they are advected back and reach within about a cylinder diameter from the face of the downstream cylinder. As the vortices advect closer to the cylinder, the vortex cores become highly deformed and wrap around the downstream cylinder face. Three-dimensional perturbations of the upstream vortices are amplified as the vortices impact upon the downstream cylinder, such that during the final stages of vortex impact the quasi-two-dimensional nature of the flow breaks down and the vorticity field for the impacting vortices acquire significant three-dimensional perturbations. Quasi-two-dimensional and fully three-dimensional computational results are compared to assess the accuracy of the quasi-two-dimensional approximation in prediction of drag and lift coefficients of the cylinders.

Aero-Thermal Investigation of a Rib-Roughened Trailing Edge Channel With Crossing-Jets: Part I—Flow Field Analysis

2008 ◽  
Author(s):  
Alessandro Armellini ◽  
Filippo Coletti ◽  
Tony Arts ◽  
Christophe Scholtes
Keyword(s):  
Flow Field ◽  
Computational Study ◽  
Three Dimensional ◽  
Side Wall ◽  
Field Analysis ◽  
Trailing Edge ◽  
Present Contribution ◽  
Numerical Predictions ◽  
Flow Features ◽  
Rib Roughened

The present contribution addresses the aero-thermal experimental and computational study of a trapezoidal cross-section model simulating a trailing edge cooling cavity with one rib-roughened wall. The flow is fed through tilted slots on one side wall and exits through straight slots on the opposite side wall. The flow field aerodynamics is investigated in part I of the paper. The reference Reynolds number is defined at the entrance of the test section and set at 67500 for all the experiments. A qualitative flow model is deduced from surface-streamline flow visualizations. Two-dimensional Particle Image Velocimetry measurements are performed in several planes around mid-span of the channel and recombined to visualize and quantify three-dimensional flow features. The jets issued from the tilted slots are characterized and the jet-rib interaction is analyzed. Attention is drawn to the motion of the flow deflected by the rib-roughened wall and impinging on the opposite smooth wall. The experimental results are compared with the numerical predictions obtained from the finite volume, RANS solver CEDRE.

Numerical Investigation of Positive Displacement Rotary Lobe Pump With Twisted Rotors

2014 ◽  
Author(s):  
Xiaojun Jiang ◽  
Yi Li ◽  
Zhaohui He ◽  
Cui Baoling ◽  
Wenlong Dong
Keyword(s):  
Flow Structure ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Dynamic Flow ◽  
Flow Fluctuation ◽  
Flow Field Characteristics ◽  
Lobe Pump ◽  
The Impact

The three-dimensional flow field characteristics are obtained by performing numerical simulation of flow in a lobe pump with twisted rotors. The relationship between the dynamic flow structure and the flow fluctuation is explored. Actually, the viscous incompressible Navier-Stokes equations are solved within an unsteady flow model. The dynamic mesh technique is applied to obtain the dynamic flow structure. By comparing the simulated results of straight rotor with those of twisted rotor, the effect of rotor shape on the flow fluctuation was revealed. Finally, the impact of the lobes number of rotors on flow pulsations is discussed. The results show that there is an intrinsic relationship between the flow fluctuation and the vortex in the lobe pump. The use of twisted rotors can effectively improve the internal flow characteristics of lobe pump and reduce flow fluctuation. With the increase of the number of lobes, the lobe pump output is more stable and capacity has been improved.

CFD-Analysis of the Combustion in the Primary Stage of a Two-Stage Combustion Chamber

2002 ◽  
Author(s):  
Klaus Hoerzer ◽  
Hermann Haselbacher ◽  
Anthony J. Griffiths ◽  
Nick Syred ◽  
Thomas A. Fraser
Keyword(s):  
Combustion Chamber ◽  
Mixture Fraction ◽  
Three Dimensional ◽  
Tangential Velocity ◽  
Reynolds Stress Model ◽  
Swirl Flow ◽  
Wood Powder ◽  
Two Stage ◽  
Primary Stage ◽  
Combustion Flow

Combustion of wood powder may be applied in a two-stage multi-inlet combustion chamber. The primary stage of the combustion chamber has tangential air inlets to provide high swirl flow. The wood powder and its conveying air enter the gasification chamber axially through a center inlet in the bottom. The aim of the investigation was the analysis of the combustion flow of the primary stage of the combustion chamber. The calculation grid was three-dimensional and unstructured. Turbulence was modelled with the Reynolds-Stress-Model, species with mixture fraction/pdf-approach, radiation with the P1-model. Postprocessing has been done for particle tracks, the temperature distribution and tangential velocity distribution and for the species distributions of solid carbon, carbon monoxide, carbon dioxide and oxygen as well.

Finite Element Prediction of Multi-Size Particulate Flow Through Three-Dimensional Pump Casing

2015 ◽  
Author(s):  
Krishnan V. Pagalthivarthi ◽  
John M. Furlan ◽  
Robert J. Visintainer
Keyword(s):  
Finite Element ◽  
Field Data ◽  
Complex Geometry ◽  
Three Dimensional ◽  
Side Wall ◽  
Secondary Flows ◽  
Low Flow ◽  
Particulate Flow ◽  
Main Stream ◽  
Flow Through

Flow through centrifugal pump casing is highly complex in nature due to the complex geometry of the casing. While simplified two dimensional modeling of pump casing reveals the overall flow pattern and pressure distribution, a complete 3D model of pump casing is essential to fully capture the interaction of the primary main stream flow and the secondary flows especially in areas of heavy recirculation. This paper presents steady state finite element simulation of multi-size particulate slurry flow through three dimensional pump casing. The flow field and concentration distribution is presented for different cross-sectional planes. The multi-size particulate flow simulation results are compared with two mono-size particle simulations using (1) the concentration weighted mean diameter of the slurry and (b) the D50 size of the slurry. Qualitative comparison is made with the wear rate predicted by the simulations and the field data. Simulations and field data show that at low flow rates, the side-wall gouging wear near the tongue region becomes significant.

Pressure Drops of Water Flow Through Micromachined Particle Filters

2002 ◽  
Vol 124 (4) ◽  
pp. 1053-1056 ◽  
Author(s):  
Tzung K. Hsiai ◽  
Sung Kwon Cho and ◽  
Joon Mo Yang ◽  
Xing Yang and ◽  
Yu-Chong Tai ◽  
...  
Keyword(s):  
Water Flow ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Side Wall ◽  
Micro Electro Mechanical System ◽  
Numerical Code ◽  
Power Requirement ◽  
Pressure Drops ◽  
Flow Through ◽  
Wall Profile

When the particle is in the order of microns, flow through the small opening produces a large velocity gradient, leading to high viscous dissipation. Understanding the flow field is critical in determining the power requirement. In this paper, we studied water flow through filters fabricated by micro-electro-mechanical system (MEMS) techniques. The pressure drop calculated by a three-dimensional numerical code of the Navier-Stokes equations is in a resonable agreement with the experimental data if the diameter and the side wall profile of the holes are measured with high accuracy.

Simulation Research on Micro-Cavity Flow Field Characteristics of Liquid Floating Rotor Gyro

2013 ◽  
Vol 562-565 ◽  
pp. 490-495 ◽  
Author(s):  
Yu Peng Shi ◽  
Fei Tang ◽  
Xiao Hao Wang
Keyword(s):  
Flow Field ◽  
Boundary Conditions ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Cavity Flow ◽  
Three Dimensional Model ◽  
Simulation Research ◽  
Resistance Torque ◽  
Flow Field Characteristics ◽  
Micro Cavity

The liquid floating rotor gyro is a gyroscope using electrostatic or electromagnetic forces to levitate rotor, and filling rotor-stator cavities with liquid in order to improve stability of motion. Under influence of the relative surface roughness, rotor velocity, dimension of flow field and fluid nature, flow characteristics of cavity flow field vary under different boundary conditions and geometrical conditions. This paper adopts three-dimensional model and periodic boundary conditions to conduct numerical modeling on cavity flow field. Its results show that, with velocity rising, distribution of flow field speed and pressure manifests partial fluctuations in turbulent-flow-intensive area; resistance torque amid rotor rotation is nonlinearly correlated with velocity, whose rules can be obtained through high-order curve fitting.

A Numerical Analysis of Bidirectional Ducted Tidal Turbines in Yawed Flow

2013 ◽  
Vol 47 (4) ◽  
pp. 23-35 ◽  
Author(s):  
Clarissa S.K. Belloni ◽  
Richard H.J. Willden ◽  
Guy T. Houlsby
Keyword(s):  
Computational Study ◽  
Three Dimensional ◽  
Turbine Rotor ◽  
Navier Stokes ◽  
External Diameter ◽  
Tidal Turbines ◽  
Turbine Performance ◽  
Ducted Turbine ◽  
Flow Through ◽  
Porous Disc

AbstractThe paper presents a computational study of ducted bidirectional tidal turbines using three-dimensional Reynolds-averaged Navier-Stokes simulations. We model the outer duct as a solid body and use a porous disc to represent the turbine rotor, a simplification that captures changes in linear momentum and thus the primary interaction of the turbine with the flow through and around the duct while greatly reducing computational complexity. The duct is modeled using linearly converging and diverging sections and a short straight pipe at the duct throat.We investigate the performance of bare and ducted turbines and relate these to the flows through the devices. For the ducted turbine under investigation, we show a substantial decrease in power generated relative to a bare turbine of diameter equal to the external diameter of the duct. In the case of ducted turbines with concave duct exteriors, we observe two external flow regimes with increasing turbine thrust: nozzle-contoured and separation dominated regimes. Maximum power occurs within the separation dominated flow regime due to the additional channel blockage created by the external separation.The ducts of ducted tidal turbines have been argued to provide a flow straightening effect, allowing modest yaw angles to be readily accommodated. We present a comparison of bare and ducted turbine performance in yawed flow. We show that while bare turbine performance decreases in yawed flow, ducted turbine performance increases. This is due to both a flow straightening effect and also an increase in effective blockage as ducts present greater projected frontal area when approached nonaxially.

An Experimental/Computational Study of Airflow in the Combustor–Diffuser System of a Gas Turbine for Power Generation

1998 ◽  
Vol 120 (1) ◽  
pp. 24-33 ◽  
Author(s):  
A. K. Agrawal ◽  
J. S. Kapat ◽  
T. T. Yang
Keyword(s):  
Gas Turbines ◽  
Computational Study ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Strong Interactions ◽  
Test Model ◽  
Computational Fluid Dynamic Analysis ◽  
Flow Measurements ◽  
Venturi Effect

This paper presents an experimental/computational study of cold flow in the combustor–diffuser system of industrial gas turbines employing can-annular combustors and impingement-cooled transition pieces. The primary objectives were to determine flow interactions between the prediffuser and dump chamber, to evaluate circumferential flow nonuniformities around transition pieces and combustors, and to identify the pressure loss mechanisms. Flow experiments were conducted in an approximately one-third geometric scale, 360-deg annular test model simulating practical details of the prototype including the support struts, transition pieces, impingement sleeves, and can-annular combustors. Wall static pressures and velocity profiles were measured at selected locations in the test model. A three-dimensional computational fluid dynamic analysis employing a multidomain procedure was performed to supplement the flow measurements. The complex geometric features of the test model were included in the analysis. The measured data correlated well with the computations. The results revealed strong interactions between the prediffuser and dump chamber flows. The prediffuser exit flow was distorted, indicating that the uniform exit conditions typically assumed in the diffuser design were violated. The pressure varied circumferentially around the combustor casing and impingement sleeve. The circumferential flow nonuniformities increased toward the inlet of the turbine expander. A venturi effect causing flow to accelerate and decelerate in the dump chamber was also identified. This venturi effect could adversely affect impingement cooling of the transition piece in the prototype. The dump chamber contained several recirculation regions contributing to the losses. Approximately 1.2 dynamic head at the prediffuser inlet was lost in the combustor–diffuser, much of it in the dump chamber where the fluid passed though narrow pathways. A realistic test model and three-dimensional analysis used in this study provided new insight into the flow characteristics of practical combustor–diffuser systems.

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