Investigation on a Gas-Liquid Ejector Using Three-Dimensional CFD Modeling

2012 ◽  
Author(s):  
Sanghoon Kang ◽  
Xueguan Song ◽  
Kyunghun Kim ◽  
Youngchul Park
Keyword(s):  
Numerical Model ◽  
3D Model ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Mesh Size ◽  
Grid Size ◽  
Cfd Modeling ◽  
Cfd Analysis ◽  
Ansys Cfx ◽  
Primary Fluid

This work is focusing on the numeral study of a gas-liquid ejector used for ballast water treatment. The gas-liquid ejector is investigated through steady three-dimensional multiphase CFD analysis with commercial software ANSYS-CFX. Water as the primary fluid is driven through the driving nozzle and air is ejected into as the second gas instead of the ozone in real application. Several turbulence models such as Standard k-ε, RNG k-ε, SST, and k-ω, and different grid size are compared extensively with the experimental results to eliminate the influence of the auxiliary system. The appropriate numerical model in terms of the best combination of simplified 3D model, turbulence model and mesh size are used in the subsequent research to study the influence of the operating condition such as the driving pressure/velocity. And the proposed numerical model will be very helpful in the further design optimization of the gas-liquid ejectors.

CFD Modeling and Simulation of Aeorodynamic Cooling of Automotive Brake Rotor

2018 ◽  
Vol 09 (01) ◽  
pp. 1750008 ◽  
Author(s):  
Ali Belhocien ◽  
Wan Zaidi Wan Omar
Keyword(s):  
Heat Dissipation ◽  
Surface Film ◽  
Transient State ◽  
Cfd Modeling ◽  
Disc Brake ◽  
Cfd Analysis ◽  
Braking System ◽  
Airflow Distribution ◽  
Ansys Cfx ◽  
Brake Rotor

Braking system is one of the important control systems of an automotive. For many years, the disc brakes have been used in automobiles for the safe retarding of the vehicles. During the braking enormous amount of heat will be generated and for effective braking sufficient heat dissipation is essential. The thermal performance of disc brake depends upon the characteristics of the airflow around the brake rotor and hence the aerodynamics is an important in the region of brake components. A CFD analysis is carried out on the braking system as a case study to make out the behavior of airflow distribution around the disc brake components using ANSYS CFX software. We are interested in the determination of the heat transfer coefficient (HTC) on each surface of a ventilated disc rotor varying with time in a transient state using CFD analysis, and then imported the surface film condition data into a corresponding FEM model for disc temperature analysis.

scholarly journals Progress in Phenomenological Modeling of Turbulence Damping around a Two-Phase Interface

Fluids ◽  
2019 ◽  
Vol 4 (3) ◽  
pp. 136 ◽  
Author(s):  
Wenyuan Fan ◽  
Henryk Anglart
Keyword(s):  
Turbulence Modeling ◽  
Phase Interface ◽  
Turbulence Models ◽  
Mesh Size ◽  
Tangential Direction ◽  
Cfd Modeling ◽  
Two Phase ◽  
Simple Formulation ◽  
Phenomenological Modeling ◽  
Gas Phases

The presence of a moving interface in two-phase flows challenges the accurate computational fluid dynamics (CFD) modeling, especially when the flow is turbulent. For such flows, single-phase-based turbulence models are usually used for the turbulence modeling together with certain modifications including the turbulence damping around the interface. Due to the insufficient understanding of the damping mechanism, the phenomenological modeling approach is always used. Egorov’s model is the most widely-used turbulence damping model due to its simple formulation and implementation. However, the original Egorov model suffers from the mesh size dependency issue and uses a questionable symmetric treatment for both liquid and gas phases. By introducing more physics, this paper introduces a new length scale for Egorov’s model, making it independent of mesh sizes in the tangential direction of the interface. An asymmetric treatment is also developed, which leads to more physical predictions for both the turbulent kinetic energy and the velocity field.

New Methods for Secondary Flow Phenomena Visualization and Analysis

2019 ◽  
Author(s):  
Mattia Straccia ◽  
Rodolfo Hofmann ◽  
Volker Gümmer
Keyword(s):  
Secondary Flow ◽  
Boundary Layers ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Secondary Flows ◽  
Tip Leakage ◽  
Ansys Cfx ◽  
Flow Phenomena ◽  
Visualization Techniques ◽  
Operating Points

Abstract This work focuses on presenting new techniques for the visualization of Secondary Flow Phenomena (SFP) in transonic turbomachinery. Here, Rotor 37 has been used to develop and apply these techniques in order to study vortices, shocks and secondary flows. They are also used to provide a comparison between turbulence models in Ansys CFX environment, here the Spalart-Allmaras (SA) and Shear Stress Tensor (SST) turbulence models. The scope of this paper is to give an improved understanding of SFP and how their onset and evolution are influenced from the turbulence model. The analysis is based on results of three-dimensional steady-state RANS simulations, for operating points between design point and near-stall condition, achieved by varying the outlet static pressure radial equilibrium distribution at the rotor exit. The new visualization techniques highlight important flow field features less investigated in previous research works, in particular secondary weak strength vortices. They will give a better visualization of and insight to the interaction of the passage shock and the tip leakage vortex, the interaction between vortices and boundary layers and the interaction of the shock wave and endwall boundary layers.

CFD Analysis of Coolant Flow in VVER-440 Fuel Assemblies with the Code ANSYS CFX 10.0

2006 ◽  
Author(s):  
Sa´ndor To´th ◽  
Ga´bor Le´gra´di ◽  
Attila Aszo´di
Keyword(s):  
Flow Field ◽  
Fuel Assembly ◽  
Nuclear Reactors ◽  
Turbulence Models ◽  
Sensitivity Study ◽  
Cfd Analysis ◽  
Type Reactor ◽  
Ansys Cfx ◽  
Fuel Assemblies ◽  
Fuel Pin

From the aspect of planning the power upgrading of nuclear reactors — including the VVER-440 type reactor — it is essential to get to know the flow field in the fuel assembly. For this purpose we have developed models of the fuel assembly of the VVER-440 reactor using the ANSYS CFX 10.0 CFD code. At first a 240 mm long part of a 60 degrees segment of the fuel pin bundle was modelled. Implementing this model a sensitivity study on the appropriate meshing was performed. Based on the development of the above described model, further models were developed: a 960 mm long part of a 60-degree-segment and a full length part (2420 mm) of the fuel pin bundle segment. The calculations were run using constant coolant properties and several turbulence models. The impacts of choosing different turbulence models were investigated. The results of the above-mentioned investigations are presented in this paper.

scholarly journals Simulation and Analysis of a Turbulent Flow Around a Three-Dimensional Obstacle

2019 ◽  
Vol 13 (3) ◽  
pp. 173-180
Author(s):  
Lamia Benahmed ◽  
Khaled Aliane
Keyword(s):  
Shear Stress ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Turbulence Models ◽  
Governing Equations ◽  
Complex Behaviour ◽  
Ansys Cfx ◽  
Recirculation Zones ◽  
Volume Method ◽  
Calculation Code

Abstract The study of flow around obstacles is devised into three different positions: above the obstacle, upstream of the obstacle, and downstream of the latter. The behaviour of the fluid downstream of the obstacle is less known, and the physical and numerical modelling is being given the existence of recirculation zones with their complex behaviour. The purpose of the work presented below is to study the influence of the inclined form of the two upper peaks of a rectangular cube. A three-dimensional study was carried out using the ANSYS CFX calculation code. Turbulence models have been used to study the flow characteristics around the inclined obstacle. The time-averaged results of contours of velocity vectors <V>, cross-stream <v> and stream wise velocity <u> and streamlines were obtained by using K-ω shear -stress transport (SST), RANG K-ε and K-ε to model the turbulence, and the governing equations were solved using the finite volume method. The turbulence model K-ω SST has presented the best prediction of the flow characteristics for the obstacle among the investigated turbulence models in this work.

Three-Dimensional CFD Analysis on Gas Flow in Corrugated Wall Channel

2006 ◽  
Author(s):  
Nam-il Tak ◽  
Won-Jae Lee ◽  
Jonghwa Jang
Keyword(s):  
Heat Exchanger ◽  
Turbulent Flows ◽  
Gas Flow ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Cfd Analysis ◽  
Intermediate Heat Exchanger ◽  
Computational Fluid Dynamics Cfd ◽  
Corrugated Wall ◽  
Selection Of

A printed circuit heat exchanger (PCHE) is known as one of the promising types for an intermediate heat exchanger (IHX) of a nuclear hydrogen production system. This paper presents fundamental numerical results on gas flow behaviors in a typical PCHE geometry. Laminar and turbulent flows were analyzed based on a computational fluid dynamics (CFD) analysis. Local friction coefficient and local Nusselt number were evaluated and compared with those by typical correlations for tubes. In the case of a turbulent flow, various turbulence models were applied. The results clearly show the significance of a careful selection of a turbulence model.

CFD Modeling Effects on Unsteady Multistage Simulation for a Transonic Axial Compressor

2011 ◽  
Author(s):  
Mai Yamagami ◽  
Hidekazu Kodama ◽  
Dai Kato ◽  
Naoki Tsuchiya ◽  
Yasuo Horiguchi ◽  
...  
Keyword(s):  
Performance Prediction ◽  
High Speed ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Turbulence Models ◽  
Numerical Approach ◽  
Path Model ◽  
Cfd Modeling ◽  
Geometry Modeling ◽  
The Impact

Unsteady three-dimensional multistage calculations are performed for a highly loaded, high-speed axial compressor to investigate the impact of real geometry modeling and different numerical approaches on the accuracy of the performance prediction. First, two features of the real geometries are separately compared with the calculation which consists of a pure flow path model except that rotor tip clearances are considered. One treats leakage generated by part gaps between variable stator vanes and the annulus lines. Another incorporates seal cavities to model leakage underneath the shrouded stators. Then, the influence of different numerical approach with different turbulence models is also investigated. Discussion on the impact of the CFD modeling on the performance prediction focuses on the prediction accuracies of stage operating points and spanwise mixing. It is suggested that a realistic simulation of turbulent-type flow unsteadiness in a multistage machine is important for an accurate prediction of spanwise mixing phenomena.

Three-Dimensional Flame Structure in Wall-Fired Swirl Flame Combustors

1996 ◽  
Author(s):  
Ay Su ◽  
Ze-Chern Lee ◽  
Wu-Chi Ho
Keyword(s):  
Numerical Model ◽  
Power Plants ◽  
Mixture Fraction ◽  
Flame Structure ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Turbulence Models ◽  
Combustion Model ◽  
Reacting Flow ◽  
Inlet Conditions

A CFD solver CFX is used to analyze the complex behavior of turbulent reacting flow inside the furnace. The flow characteristics for various combustor geometries, fuel/air ratios, and injection velocities, and swirl levels are investigated. Starting with a cylindrical furnace fired with gaseous fuel from a concentric tube burner (both with and without swirl), the mixture-fraction is predicted using the k-ε and RSM turbulence models. The discrepancies between the predictions and measurements are most significant in the flame core of upstream regions. It may stem from inappropriateness of the assumed inlet conditions and the combustion model. However, the calculated results are still qualitatively acceptable. After the validation work of the numerical model, a rectangular furnace with four wall-fired swirling combustors is employed to investigate the effect of neighbouring burners and geometry on combustion characteristics. The central recirculation zone which appeared in the isothermal flowfield vanished in the combustion case. It may be attributed to the fact that the hot gas suddenly expands outward and destroys the recirculation mechanism. Thus, the central flame could not hold. In addition, the four corner flames are stretching against the wall and their shapes are similar to a “cam” profile. The results are intended to assist in the development and validation of a numerical model for predicting furnace flows in wall-fired power plants.

scholarly journals Сomputational and Experimental Investigation of Aerodynamic Characteristics of a Counter-Rotating fan Using Various Software Packages

2019 ◽  
pp. 115-130 ◽  
Author(s):  
A.A. Martirosyan ◽  
V.I. Mileshin ◽  
Ya.M. Druzhinin ◽  
P.G. Kozhemyako
Keyword(s):  
Turbulent Flows ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Aerodynamic Characteristics ◽  
Angular Frequency ◽  
Maximum Efficiency ◽  
Software Packages ◽  
Aerodynamic Properties ◽  
Ansys Cfx

The paper presents the results of computing aerodynamic properties of the CRTF2A counter-rotating cowled fan developed as part of the European VITAL program. To achieve these results, we used the following software packages: NUMECA FINE TURBO, ANSYS CFX and CIAMs own 3D--IMP--MULTI hydrocode. We use the RANS approach to model turbulent flows. We performed a three-dimensional computation, completing Reynolds-averaged Navier --- Stokes equations by various turbulence models for the following relative angular frequency modes: n = 1 and 0.9. We used the following turbulence models available in the software packages: k--ε (ANSYS CFX, 3D--IMP--MULTI), k--ε (ANSYS CFX, NUMECA FINE TURBO, 3D--IMP--MULTI), SST (NUMECA FINE TURBO, ANSYS CFX, 3D--IMP--MULTI). We plotted head characteristics for each software package and determined the main differences. We plotted adiabatic efficiency and total pressure ratios as functions of height for the first and second rotors at the maximum efficiency points for both modes in the ANSYS CFX, NUMECA FINE TURBO and 3D--IMP--MULTI software packages

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