Validation of a Three-Dimensional Internal Nozzle Flow Model Including Automatic Mesh Generation and Cavitation Effects

2014 ◽  
Vol 136 (9) ◽  
Author(s):  
Hongwu Zhao ◽  
Shaoping Quan ◽  
Meizhong Dai ◽  
Eric Pomraning ◽  
P. K. Senecal ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Nozzle Flow ◽  
Two Phase ◽  
Flow Solver ◽  
Fuel Injectors ◽  
Contour Shape ◽  
Engine Combustion ◽  
Nozzle Configuration ◽  
Computational Fluid Dynamics Cfd ◽  
Automatic Mesh

Fuel injectors often experience cavitation due to regions of extremely low pressure. In this work, a cavitation modeling method is implemented in the CONVERGE computational fluid dynamics (CFD) code in order to model the flow in fuel injectors. The CONVERGE code includes a Cartesian mesh based flow solver. In this solver, a volume of fluid (VOF) method is used to simulate the multiphase flow. The cavitation model is based on a flash-boiling method with rapid heat transfer between the liquid and vapor phases. In this method, a homogeneous relaxation model is used to describe the rate at which the instantaneous quality, the mass fraction of vapor in a two-phase mixture, will tend towards its equilibrium value. The model is first validated with the nozzle flow case of Winklhofer by comparing the mass flow rate with experimentally measured values at different outlet pressures. The cavitation contour shape is also compared with the experimental observations. Flow in the Engine Combustion Network Spray-A nozzle configuration is simulated. The mesh dependency is also studied in this work followed by validation against discharge coefficient data. Finally, calculations of a five-hole injector, including moving needle effects, are compared to experimental measurements.

Validation of a Three-Dimensional Internal Nozzle Flow Model Including Automatic Mesh Generation and Cavitation Effects

2013 ◽  
Author(s):  
Hongwu Zhao ◽  
Shaoping Quan ◽  
Meizhong Dai ◽  
Eric Pomraning ◽  
P. K. Senecal ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Nozzle Flow ◽  
Two Phase ◽  
Flow Solver ◽  
Fuel Injectors ◽  
Contour Shape ◽  
Engine Combustion ◽  
Nozzle Configuration ◽  
Automatic Mesh ◽  
Liquid And Vapor Phases

Fuel injectors often experience cavitation due to regions of extremely low pressure. In this work, a cavitation modeling method is implemented in the CONVERGE CFD code to model the flow in fuel injectors. CONVERGE includes a Cartesian mesh based flow solver. In this solver, a Volume Of Fluid (VOF) method is used to simulate the multiphase flow. The cavitation model is based on a flash-boiling method with rapid heat transfer between the liquid and vapor phases. In this method, a homogeneous relaxation model is used to describe the rate at which the instantaneous quality, the mass fraction of vapor in a two-phase mixture, will tend towards its equilibrium value. The model is first validated with the nozzle flow case of Winklhofer by comparing the mass flow rate with experimentally measured values at different outlet pressures. The cavitation contour shape is also compared with the experimental observations. Flow in the Engine Combustion Network Spray-A nozzle configuration is simulated. The mesh dependency is also studied in this work followed by validation against discharge coefficient data. Finally, calculations of a five-hole injector, including moving needle effects, are compared to experimental measurements.

Three-Dimensional Numerical Simulation of Fluid with Sparse Particles' Erosion to Pipelines

2013 ◽  
Vol 805-806 ◽  
pp. 1785-1789
Author(s):  
Chang Bin Wang ◽  
Miao Wang ◽  
Xiao Xu Li ◽  
Yu Liu ◽  
Jie Nan Dong
Keyword(s):  
Fluid Dynamics ◽  
Numerical Simulation ◽  
Flow Model ◽  
Particle Distribution ◽  
Three Dimensional ◽  
Two Phase ◽  
Wear Area ◽  
Computational Fluid Dynamics Cfd ◽  
Set Up ◽  
Volume Method

A three dimensional fluid flow model was set up in this paper, based on the computational fluid dynamics (CFD) and the elasticity theory. Using the finite volume method, a 120° bend was taken as a research object to simulate the erosion to the wall of fluid with sparse particles, finally, to determine the most severe wear areas.At the same time, the distribution of two-phase flows pressure and velocity was analyzed in 45° and 90° bends, then tracked the trajectory of the particles. The results show that the 90°bend has the smallest wear area and particle distribution or combination property is the best.

Two-Phase CFD of Channel Boiling for Boiling Transition Problems

2014 ◽  
Author(s):  
Antonin Povolny ◽  
Martin Cuhra
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
First Principles ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Two Phase ◽  
General Ability ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Traditional Approaches

In order to ensure safety of nuclear installations, thermohydraulics has developed many ways how to predict the behavior of coolant in a heated boiling channel. Accuracy of these predictions can be improved using three-dimensional Computational Fluid Dynamics (CFD) method, which is based on first principles of fluid mechanics. Even though when using CFD, there is a struggle between the accuracy and low computation costs, in many cases CFD can provide feasible improvement of accuracy compared to more traditional approaches. In this research, the focus is set on channel boiling problems, especially those associated with boiling transitions. The phenomenon of critical heat flux (CHF) is investigated using two-phase CFD computation and is compared to experimental data. There is also comparison with other computation methods. When experiment provides some set of data, CFD calculation provides description of the whole flow behavior that provides significantly more information and is of great value during the design process when it gives the understanding of undergoing effects. Besides CHF, general ability of CFD to predict changes in boiling patterns in two-phase channel boiling flows is discussed.

scholarly journals SedFoam-2.0: a 3-D two-phase flow numerical model for sediment transport

2017 ◽  
Vol 10 (12) ◽  
pp. 4367-4392 ◽  
Author(s):  
Julien Chauchat ◽  
Zhen Cheng ◽  
Tim Nagel ◽  
Cyrille Bonamy ◽  
Tian-Jian Hsu
Keyword(s):  
Sediment Transport ◽  
Two Phase Flow ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Test Cases ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Solver ◽  
Transport Problems ◽  
Stress Models

Abstract. In this paper, a three-dimensional two-phase flow solver, SedFoam-2.0, is presented for sediment transport applications. The solver is extended from twoPhaseEulerFoam available in the 2.1.0 release of the open-source CFD (computational fluid dynamics) toolbox OpenFOAM. In this approach the sediment phase is modeled as a continuum, and constitutive laws have to be prescribed for the sediment stresses. In the proposed solver, two different intergranular stress models are implemented: the kinetic theory of granular flows and the dense granular flow rheology μ(I). For the fluid stress, laminar or turbulent flow regimes can be simulated and three different turbulence models are available for sediment transport: a simple mixing length model (one-dimensional configuration only), a k − ε, and a k − ω model. The numerical implementation is demonstrated on four test cases: sedimentation of suspended particles, laminar bed load, sheet flow, and scour at an apron. These test cases illustrate the capabilities of SedFoam-2.0 to deal with complex turbulent sediment transport problems with different combinations of intergranular stress and turbulence models.

scholarly journals SedFoam-2.0: a 3D two-phase flow numerical model for sediment transport

2017 ◽  
Author(s):  
Julien Chauchat ◽  
Zhen Cheng ◽  
Tim Nagel ◽  
Cyrille Bonamy ◽  
Tian-Jian Hsu
Keyword(s):  
Sediment Transport ◽  
Two Phase Flow ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Solver ◽  
Dense Granular Flow ◽  
Transport Problems ◽  
Stress Models

Abstract. In this paper, a three-dimensional two-phase flow solver, SedFoam-2.0, is presented for sediment transport applications. The solver is extended upon twoPhaseEulerFoam available in the 2.1.0 release of the open-source CFD toolbox OpenFOAM. In this approach the sediment phase is modeled as a continuum, and constitutive laws have to be prescribed for the sediment stresses. In the proposed solver, two different inter-granular stress models are implemented: the kinetic theory of granular flows and the dense granular flow rheology μ(I). For the fluid stress, laminar or turbulent flow regimes can be simulated and three different turbulence models are available for sediment transport: a simple mixing length model (one-dimensional configuration only), a k-ϵ and a k-ω model. The numerical implementation is first demonstrated by two validation test cases, sedimentation of suspended particles and laminar bed-load. Two applications are then investigated to illustrate the capabilities of SedFoam-2.0 to deal with complex turbulent sediment transport problems with different combinations of inter-granular stress and turbulence models.

The Effect of Inlet Blade Angle Variation on Cavitation Performance of a Centrifugal Pump: A Parametric Study

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Aydın Hacı Dönmez ◽  
Zehra Yumurtacı ◽  
Levent Kavurmacıoğlu
Keyword(s):  
Centrifugal Pump ◽  
Three Dimensional ◽  
Blade Angle ◽  
Two Phase ◽  
Angle Variation ◽  
High Discharge ◽  
Cavitation Performance ◽  
Negative Effect ◽  
Computational Fluid Dynamics Cfd ◽  
Positive Effect

The aim of the current study is to investigate the effect of inlet blade angles on cavitation performance in a centrifugal pump. In order to reveal this relationship, both hub and shroud blade angles are considered and a two-phase three-dimensional computational fluid dynamics (CFD) study is carried out. Shear stress transport (SST) turbulence and Rayleigh–Plesset cavitation models are used in simulations. Inlet blade angles for both hub and shroud are changed and pump performance (head-discharge) and cavitation (head-inlet pressure) graphs are obtained for eight different designs. Afterward, numerical cavitation tests are conducted, required net positive suction head values of the each design are calculated, and variations are demonstrated. Results show that hub and shroud blade angle variations have no significant effect on the pump characteristic curves excluding for shroud blade angle at high discharge values. However, cavitation performance of the pump is excessively affected for both hub and shroud blade angle alterations. Increasing hub blade angle has slightly negative effect on cavitation performance of the pump. On the other hand, while increasing shroud blade angle from 20 deg to 30 deg have positive effect on cavitation performance, it is negatively affected from 30 deg to 50 deg.

A coupled CFD-DEM investigation of internal erosion considering suspension flow

2020 ◽  
Author(s):  
Yajing Liu ◽  
Zhen-Yu Yin ◽  
Li-Zhong Wang ◽  
Yi Hong
Keyword(s):  
Fine Particles ◽  
Coupling Effect ◽  
Three Dimensional ◽  
Fine Fraction ◽  
Local Area ◽  
Internal Erosion ◽  
Suspension Flow ◽  
Two Phase ◽  
Dem Analysis ◽  
Computational Fluid Dynamics Cfd

The influence of two-phase flows containing suspension particles, which are common in nature, on internal erosion with coupling effect of clogging remains unclear. This paper presents a three-dimensional coupled discrete element method and computational fluid dynamics (CFD-DEM) analysis of internal erosion considering different concentrations of suspension C (i.e., mass of the suspended particles in unit volume of fluid) in gap-graded granular soils with different fine fraction Fc (i.e., the percentage by mass of the fine particles in the gap-graded sample). The influences of C and Fc on the erosion and clogging behavior of soils are investigated from both the macroscopic and microscopic perspectives. It is found that for gap-graded samples being under-filled with Fc=15%, the suspension flow (i.e., influent fluid with suspending particles) decreases the cumulative eroded fine particle loss and the increasing rate of soil hydraulic conductivity due to clogging at the top of the sample. The degree of clogging is found to jointly be determined by both constriction size distribution and the suspension concentration. Clogging in a local area usually occurs with the formation of the clusters which has a high resistance to the drag force applied by the fluid flow.

scholarly journals Collaborative investigation of the internal flow and near-nozzle flow of an eight-hole gasoline injector (Engine Combustion Network Spray G)

2020 ◽  
pp. 146808742091844
Author(s):  
Chinmoy K Mohapatra ◽  
David P Schmidt ◽  
Brandon A Sforozo ◽  
Katarzyna E Matusik ◽  
Zongyu Yue ◽  
...  
Keyword(s):  
Direct Injection ◽  
Internal Flow ◽  
Gasoline Direct Injection ◽  
Two Phase ◽  
Direct Injection Engines ◽  
Fuel Injectors ◽  
Engine Combustion ◽  
Injector Flows ◽  
Eulerian Modeling ◽  
The Impact

The internal details of fuel injectors have a profound impact on the emissions from gasoline direct injection engines. However, the impact of injector design features is not currently understood, due to the difficulty in observing and modeling internal injector flows. Gasoline direct injection flows involve moving geometry, flash boiling, and high levels of turbulent two-phase mixing. In order to better simulate these injectors, five different modeling approaches have been employed to study the engine combustion network Spray G injector. These simulation results have been compared to experimental measurements obtained, among other techniques, with X-ray diagnostics, allowing the predictions to be evaluated and critiqued. The ability of the models to predict mass flow rate through the injector is confirmed, but other features of the predictions vary in their accuracy. The prediction of plume width and fuel mass distribution varies widely, with volume-of-fluid tending to overly concentrate the fuel. All the simulations, however, seem to struggle with predicting fuel dispersion and by inference, jet velocity. This shortcoming of the predictions suggests a need to improve Eulerian modeling of dense fuel jets.

Implementation of a Level Set Interface Tracking Method in the FIDAP and CFX-4 Codes

2004 ◽  
Author(s):  
Sergey V. Shepel ◽  
Brian L. Smith ◽  
Samuel Paolucci
Keyword(s):  
Level Set ◽  
Gaseous Phase ◽  
Viscosity Ratio ◽  
Density Ratio ◽  
Three Dimensional ◽  
Interface Tracking ◽  
Two Phase ◽  
Computational Fluid Dynamics Cfd ◽  
Liquid Flows ◽  
Level Set Formulation

A Streamline-Upwind/Petrov-Galerkin (SUPG) Finite Element (FE) Level Set method is presented, which may be used for solving problems involving incompressible two-phase flow with moving inter-phase boundaries. The method is three-dimensional, and can be used on both structured and unstructured grids. Two formulations are given. The first considers the coupled motion of both phases, and is implemented in the framework of the commercial Computational Fluid Dynamics (CFD) code CFX-4. The second can be applied for gas-liquid flows when effects of the gaseous phase on the motion of the liquid phase are negligible; consequently, the gaseous phase is removed from consideration. This Level Set formulation is implemented in the commercial CFD code FIDAP. The resulting Level Set formulations are tested on sample problems involving two-phase flows with density ratio of the order of 103 and viscosity ratio as high as 105. The numerical results are compared against experimental data.

Three-Dimensional Blade Design of Helico-Axial Multiphase Pump Impeller Based on Numerical Solution of Meridian Flow Net and Blade Mean Camber Lines

2011 ◽  
Author(s):  
Jinya Zhang ◽  
Hongwu Zhu ◽  
Huan Wei
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Numerical Solution ◽  
Design Method ◽  
Three Dimensional ◽  
Blade Design ◽  
Two Phase ◽  
Impeller Blade ◽  
Multiphase Pump ◽  
Contour Shape

The three-dimensional blade design method is adopted to design the blades of the impeller of a helico-axial multiphase pump. In this design method, the flow field of the impeller is computed with the hypothesis of multiphase homogeneous flow on the basis that it is the practical flow regime in the multiphase pump. The shape of the blade is obtained from a numerical solution of the meridian flow net the on meridional plane and blade mean camber lines on stream-surfaces of revolution. First, the contour shape and size of the meridian flow channel of the impeller blade is determined by parameterization design. Second, according to the discrete data of the contour shape, the meridian streamlines are determined by iterative computation based on solving the gas-liquid two phase meridional velocity gradient equation and the two phase coupled equations with quasi-orthogonals, and the flow parameters of the meridian flow net are computed simultaneously in order that the characteristics of the meridian fluid flow can be determined. And then the distribution of velocity moments can be obtained further. Third, the blade mean camber line equation is integrated with the point-by-point integral method, and then the blade mean camber line on the stream-surface of revolution which corresponds to every meridian streamline is obtained in order to form the shape of the impeller blade surface. At last, the meridional blade elements, which are the intersecting curves of blade shape surface with several meridional planes at different angles, and the variation of blade thickness, are determined. After that, the solid modeling of the three-dimensional blade of the impeller is formed. In addition, the characteristics of the flow field of the impeller and the performance of the multiphase pump are computed by CFD numerical simulation. The position where air blocking is tends to occur was analyzed on the basis of the result of numerical simulation.

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