Simulation the formation process of boiling water flow during depressurization of a high pressure vessel using OpenFoam open source

2017 ◽  
Vol 12 (2) ◽  
pp. 169-173 ◽  
Author(s):  
R.Kh. Bolotnova ◽  
V.A. Korobchinskaya
Keyword(s):  
Open Source ◽  
High Speed ◽  
Numerical Study ◽  
Mass Conservation ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Speed Flow ◽  
Initial Stage ◽  
Calculation Results ◽  
Water Outflow

A numerical study of the initial stage of water outflow process through a thin nozzle from a supercritical state in a two-dimensional axisymmetric setting is performed using the OpenFOAM software open source with the sonicFoam solver. The mathematical model of sonicFoam solver includes the equation of mass conservation, Navier-Stokes equation, internal energy conservation and equation of state of water vapor in the form of a perfect gas. Visualization of calculation results was carried out by the ParaView graphic platform. The features of supersonic high-speed flow regime in a jet accompanied by the formation of a hollow jet in a form close to parabolic are investigated.

Numerical Study on Aerodynamic Performances of CRH3 under Crosswind

2012 ◽  
Vol 215-216 ◽  
pp. 992-997
Author(s):  
Hong Yuan Su ◽  
Ming Li ◽  
Dong Ping Wang ◽  
Feng Liu
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
Lateral Force ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Aerodynamic Properties ◽  
Aerodynamic Performances ◽  
Volume Method ◽  
Incompressible Navier Stokes Equation ◽  
Multiple Units

Based on 3D steady and incompressible Navier-Stokes equation and standard k-ε turbulent model, numerical calculation for the aerodynamic properties of EMU (Electric Multiple Units) CRH3 (China Railway High-Speed 3)running in crosswind were carried out by finite volume method. Aerodynamic performances of EMU CRH3 were analyzed and compared, when the EMU was running in different speed and under the crosswinds of different velocity. The research showed that with the change of speed of train and crosswind, the surface pressure and aerodynamic forces altered according to a certain rule. Compared with the drag, the change of lift and lateral force caused by the increase of crosswind were more serious. When the speed of train was constant of 200km/h, 250km/h and 300km/h, the drag of train increased by 26.7%, 20.4% and 19.8% respectively as the speed of crosswind increased from 12.5m/s to 30m/s, the lift of train increased by 340.7%, 331.7% and 337.1% respectively, and the lateral force of train increases by 296.3%, 266.0% and 150.2% respectively. As the speed of crosswind increases, the increase of drag caused by the acceleration of train is more serious than lift and lateral force.

Numerical Study on Control of Sunroof Buffeting

2021 ◽  
Vol 13 (2) ◽  
Author(s):  
K. Vijaykumar ◽  
S. Poonkodi ◽  
A.T. Sriram
Keyword(s):  
Numerical Study ◽  
Leading Edge ◽  
Dominant Frequency ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Ansys Fluent ◽  
Flow Modification ◽  
Numerical Result ◽  
Modification Technique ◽  
Commercial Solver

Sunroof has become one of the essential features of a luxury car, and it provides natural air circulation and good illumination into the car. But the primary problem associated with it is the buffeting noise which causes discomfort to the passengers. Though adequate studies were carried out on sunroof buffeting, efficient control techniques are needed to be developed from fundamental mechanism. To reduce the buffeting noise, flow modifications at the entrance of the sunroof is considered in this study. The internal portion of the car with sunroof is simplified into a shear driven open cavity, and two-dimensional numerical simulations are carried out using commercial solver, ANSYS Fluent. Reynolds averaged Navier-Stokes equation is used with the realizable k-? turbulence model. The unsteady numerical result obtained in this study is validated with the available experimental results for the dominant frequency. The prediction is good agreement with experiment. Flow modification technique is proposed to control the sunroof buffeting by implementing geometric modifications. A hump has been placed near the leading edge of the cavity which resulted in significant reduction of pressure oscillations. Parametric studies have been performed by varying the height of hump and the distance of hump from the leading edge. There is no prominent difference when the height of the hump is varied. As the distance of the hump from the leading edge is reduced, the sound pressure level decreases.

scholarly journals Conjugate Solutions of Navier-Stokes Equation with Deformed Pore Structure

2014 ◽  
Vol 8 ◽  
pp. 30-48
Author(s):  
V.I. Popkov ◽  
V.I. Astafiev ◽  
V.P. Shakshin ◽  
S.V. Zatsepina
Keyword(s):  
Stokes Equation ◽  
Deformation Theory ◽  
Cluster Structure ◽  
Mass Conservation ◽  
Navier Stokes ◽  
Porous Space ◽  
Navier Stokes Equation ◽  
Linear Solution ◽  
Regional Problems ◽  
Final Speed

Within the framework of block self-organizing of geological bodies with use of deformation theory the mathematical solution of a problem for effective final speed is proposed. The analytical and numerical integrated solutions of Navier-Stokes equation for deformable porous space were obtained. The decisions of multi-scaled regional problems «on a flow basis» were also presented: from lithology of rock space - to a well and from a well - to petro-physics. The evolutionary transformation of the linear solution of the equation on mass conservation up to the energetically stable non-linear solution of the equation on preserving the number of movements is also offered. Basing upon the analytical solution of Navier-Stokes equation and model of A.N. Kolmogorov we have obtained the energy model of turbulence pulsing controlled chaos, conjugated with risk stability of average well inflow and cluster structure of Earth defluidization.

Numerical Study of Deterministic Fluxes in Compressor Passages

2018 ◽  
Vol 140 (10) ◽  
Author(s):  
Feng Wang ◽  
Mauro Carnevale ◽  
Luca di Mare
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
Navier Stokes ◽  
Design Stage ◽  
Reynolds Stresses ◽  
Mean Flow ◽  
Radial Profiles ◽  
And Performance ◽  
Stage Matching ◽  
Unsteady Effects

Computational fluid dynamics (CFD) has been widely adopted in the compressor design process, but it remains a challenge to predict the flow details, performance, and stage matching for multistage, high-speed machines accurately. The Reynolds Averaged Navier-Stokes (RANS) simulation with mixing plane for bladerow coupling is still the workhorse in the industry and the unsteady bladerow interaction is discarded. This paper examines these discarded unsteady effects via deterministic fluxes using semi-analytical and unsteady RANS (URANS) calculations. The study starts from a planar duct under periodic perturbations. The study shows that under large perturbations, the mixing plane produces dubious values of flow quantities (e.g., whirl angle). The performance of the mixing plane can be considerably improved by including deterministic fluxes into the mixing plane formulation. This demonstrates the effect of deterministic fluxes at the bladerow interface. Furthermore, the front stages of a 19-blade row compressor are investigated and URANS solutions are compared with RANS mixing plane solutions. The magnitudes of divergence of Reynolds stresses (RS) and deterministic stresses (DS) are compared. The effect of deterministic fluxes is demonstrated on whirl angle and radial profiles of total pressure and so on. The enhanced spanwise mixing due to deterministic fluxes is also observed. The effect of deterministic fluxes is confirmed via the nonlinear harmonic (NLH) method which includes the deterministic fluxes in the mean flow, and the study of multistage compressor shows that unsteady effects, which are quantified by deterministic fluxes, are indispensable to have credible predictions of the flow details and performance of compressor even at its design stage.

OPEN SOURCE COMPUTATIONS OF PLANING HULL RESISTANCE

2015 ◽  
Vol 157 (B2) ◽  
Author(s):  
M Ferrando ◽  
S Gaggero ◽  
D Villa
Keyword(s):  
Open Source ◽  
Navier Stokes ◽  
Experimental Measurements ◽  
Navier Stokes Equation ◽  
Free Surfaces ◽  
Hydrodynamic Parameters ◽  
Physical Problems ◽  
Engineering Problems ◽  
Simulation Strategy ◽  
Computational Fluid Dynamics Cfd

In recent years, the application of Computational Fluid Dynamics (CFD) methods experienced an exponential growth: the increase of the computational performances and the generalization of the Navier-Stokes equation to more complex physical problems made possible the solution of complex problems like free surfaces flows. The physical complexity of planing hulls flows poses some issues in the ability to numerically predict the global hydrodynamic parameters (hull resistance, dynamic attitude) of these configurations and on the expected confidence on the numerical results. In the last decade, commercial RANS software have been successfully applied for the prediction of the planing hull characteristics with reasonable correlation to the available experimental measurements. Recently, moreover, the interest in Open Source approaches, also for the solution of engineering problems, has rapidly grow. In this work, a set of calculations on a systematic series standard hull shape has been carried out, adopting from pre- to post- processing only Open Source tools. The comparison and the validation, through the available experimental measurements, of the computed results will define an optimal simulation strategy to include this kind of tools in the usual design loop.

Investigation of the Flow Structures in Supersonic Free and Impinging Jet Flows

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
C. Chin ◽  
M. Li ◽  
C. Harkin ◽  
T. Rochwerger ◽  
L. Chan ◽  
...  
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
Experimental Studies ◽  
Turbulence Models ◽  
Impinging Jet ◽  
Optical Methods ◽  
Navier Stokes ◽  
Jet Flows ◽  
Shock Cell ◽  
Rans Turbulence Models

A numerical study of compressible jet flows is carried out using Reynolds averaged Navier–Stokes (RANS) turbulence models such as k-ɛ and k-ω-SST. An experimental investigation is performed concurrently using high-speed optical methods such as Schlieren photography and shadowgraphy. Numerical and experimental studies are carried out for the compressible impinging at various impinging angles and nozzle-to-wall distances. The results from both investigations converge remarkably well and agree with experimental data from the open literature. From the flow visualizations of the velocity fields, the RANS simulations accurately model the shock structures within the core jet region. The first shock cell is found to be constraint due to the interaction with the bow-shock structure for nozzle-to-wall distance less than 1.5 nozzle diameter. The results from the current study show that the RANS models utilized are suitable to simulate compressible free jets and impinging jet flows with varying impinging angles.

scholarly journals High-Speed Flow in an Annular Cascade With Tip Clearance: Numerical Investigation

1998 ◽  
Author(s):  
E. S. Politis ◽  
K. C. Giannakoglou ◽  
K. D. Papailiou
Keyword(s):  
High Speed ◽  
High Reynolds Number ◽  
Tip Clearance ◽  
Navier Stokes ◽  
High Speed Flow ◽  
Numerical Predictions ◽  
Simulated Experiment ◽  
Speed Flow ◽  
High Reynolds ◽  
Annular Cascade

The high-speed flow in an annular cascade with two tip clearance sizes is numerically modeled using a Navier-Stokes solver and the high-Reynolds-number k-ε turbulence model. The numerical predictions should be regarded as complementary to the experimental work conducted in the NTUA annular cascade facility, designed for studying tip-clearance effects in compressor cascades. In the numerically simulated experiment, the stationary blades are mounted on the casing and the tip clearance is formed between them and the spinning hub. The purpose of the present paper is to scrutinize flow trends identified during the measurements and elucidate the flow patterns in the blade passage for rotating and stationary hub.

An Aid to Learn Computational Fluid Dynamics: Immersed-Boundary-Based Simulation of 2D Flow

Volume 1 ◽  
2004 ◽  
Author(s):  
Sungsu Lee ◽  
Kyung-Soo Yang ◽  
Jong-Yeon Hwang
Keyword(s):  
Complex Geometry ◽  
Mass Conservation ◽  
Computational Method ◽  
Staggered Grid ◽  
Navier Stokes ◽  
Immersed Boundary ◽  
Step Method ◽  
Fractional Step Method ◽  
Navier Stokes Equation ◽  
Finite Volume Approach

Development of geometry-independent computational method and educational codes for simulation of 2D flows around objects of complex geometry is presented. Referred as immersed boundary method, it introduces virtual forcing to governing equations to represent the effect of physical boundaries. The present method is based on a finite-volume approach on a staggered grid with a fractional-step method to solve Navier-Stokes equation and continuity equation. Both momentum and mass forcings are introduced on and inside the object to satisfy no-slip condition and mass conservation. Since Cartesian grid lines in general do not coincide with the immersed boundaries, several interpolation schemes are employed. Several examples are simulated using the method presented in this study and the results agree well with other results. Both user-friendly preprocessor with GUI and FORTRAN-based solver are open to the public for educational purposes.

Computations of the Compressible Multiphase Flow Over the Cavitating High-Speed Torpedo

2003 ◽  
Vol 125 (3) ◽  
pp. 459-468 ◽  
Author(s):  
F. M. Owis ◽  
Ali H. Nayfeh
Keyword(s):  
High Speed ◽  
Multiphase Flows ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Multiphase System ◽  
System Of Equations ◽  
Cavitating Flows ◽  
Navier Stokes Equations ◽  
Compressible Multiphase Flow ◽  
Speed Flow

For high-speed cavitating flows, compressibility becomes significant in the liquid phase as well as in the vapor phase. In addition, the compressible energy equation is required for studying the effects of the propulsive jet on the cavity. Therefore, a numerical method is developed to compute cavitating flows over high-speed torpedoes using the full unsteady compressible Navier-Stokes equations. The multiphase system of equations is preconditioned for low-speed flow computations. Using the mass fraction form, we derive an eigensystem for both the conditioned and the nonconditioned system of equations. This eigensystem provides stability for the numerical discretization of the convective flux and increases the convergence rate. This method can be used to compute single as well as multiphase flows. The governing equations are discretized on a structured grid using an upwind flux difference scheme with flux limits. Single as well as multiphase flows are computed over a cavitating torpedo. The results indicate that the preconditioned system of equations converges rapidly to the required solution at very low speeds. The theoretical results are in good agreement with the measurements.

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