WSEAS Transactions on Fluid Mechanics

Print ISSN: 1790-5087
E-ISSN: 2224-347X

Volume 11, 2016

Notice: As of 2014 and for the forthcoming years, the publication frequency/periodicity of WSEAS Journals is adapted to the 'continuously updated' model. What this means is that instead of being separated into issues, new papers will be added on a continuous basis, allowing a more regular flow and shorter publication times. The papers will appear in reverse order, therefore the most recent one will be on top.

Volume 11, 2016

Title of the Paper: Modelling of a Safety Relief Valve through a MATLAB-Simulink and CFD Based Approach

Authors: M. D. L. Dalla Vedova, P. Maggiore, G. Riva

Abstract: The aim of the work is to understand the proper way to address the design and optimization procedures of a hydraulic safety relief valve. These valves are a part of the hydraulic circuit of many aircraft models, so their performances must be adapted to the specific system or engine. The only real constraints are the geometrical dimensions and the need to limit the weight of the device. This work requires gathering all the possible information available in the literature, and condensing them in a set of operations that will allow to promptly manufacture a product fitting the requirements needed. This should lead to the reduction of the amount of physical prototypes needed to obtain testing devices. The process studied uses a numerical fluid dynamic calculation approach to define the pressure field inside the valve and the forces acting on it, together with a Computational Fluid Dynamic (CFD) calculation used to identify the force distribution inside the valve. The first step deals with the creation of a CAD model of the valve. Then the CAD is imported into the CFD software, which evaluates the pressure field required to calculate the forces acting on the poppet of the valve. After the numerical scheme has been calibrated, some investigations are done to reduce the computational cost: the final goal is to run a complete simulation (meshing and solving) on a standard (even if high-end) laptop or desktop PC. Some of the positions (i.e. strokes) of the valve have been simulated as static, so a steady-state condition has been applied to solve the motion field. The main result consists of creating a MATLABSimulink ® model capable to reach results comparable to that obtained by the CFD simulation, but in faster times. This means relying on a first-guess instrument, capable to address an initial design geometry. The further use of the Look-Up Tables (LUTs) increases the time required to obtain a solution, but links the Simulink model to the CFD simulation in order to reduce the amount of modeled quantities in favor of a greater precision of the model.

Keywords: Pressure relief valve, hydraulic system, lumped parameters numerical model, orifice flow, steady CFD, quasi-dynamic numerical simulation

WSEAS Transactions on Fluid Mechanics, ISSN / E-ISSN: 1790-5087 / 2224-347X, Volume 11, 2016, Art. #22, pp. 173-178

Title of the Paper: Cavitation Bubble Interaction Close to Ultra-Hydrophobic Surface

Authors: Darina Jasikova, Michal Kotek, Milos Muller, Vaclav Kopecky

Abstract: The cavitation bubble has a great potential to be used for local surface hardening. The highly controlled and geometrically placed defined bubbles can easily machine the area of interest modifying the surface of material. However, the effect of pointed pressure hit can be sometimes undesirable. Usage of ultra-hydrophobic cover could shield and spread the force in certain part of working. The aim of this project was to design a setup of Laser Induced Breakup and study the effect of cavitation bubble on ultra-hydrophobic surface. The main interest was focused on the air film behavior that is created on the surface in liquids. Here we used 532nm Nd:YAG pulse laser for the cavitation bubble generation. The process and the impact of cavitation bubble was visualized using high speed shadowgraph.

Keywords: Laser Induced Breakdown, Shadowgraph, Cavitation bubble, Hydrophobic Surface

WSEAS Transactions on Fluid Mechanics, ISSN / E-ISSN: 1790-5087 / 2224-347X, Volume 11, 2016, Art. #21, pp. 166-172

Title of the Paper: The Development of Knowledge-Shelf to Support the Generation of a Set-Based Design of Surface Jet Pump

Authors: Supriana Suwanda, Noodhir S. Sobun, Ahmed Al-Ashaab, Muhammad S. Khan, Abdullah Rehman, Najam Beg

Abstract: Set-based Concurrent Engineering (SBCE) is advocated in order to provide an environment where design space is explored thoroughly leading to enhanced innovation. This is achieved by considering an alternative set of solutions after gaining knowledge to narrow down the solutions until the optimal solution is reached. Knowledge provision is essential in SBCE application. Hence there is a need for a tool that provides appropriate knowledge environment to enable SBCE and supports it in taking right decisions. At the same time there is a need to capture the rationale of the alternative design decisions taken during the process of narrowing down the set of the design in the SBCE environment. These decision rationales constitute important knowledge to be re-used in developing new products. In this research the tool designed to address this research rationale is called Knowledge-Shelf (K-Shelf). This paper and its outcome serve the groundwork for the development of K-Shelf software that captures knowledge and in generating the first design set in SBCE environment based on previous knowledge documented. This paper is a collaborative work from a case study of Surface Jet Pump (SJP) between the LeanPPD research group in Cranfield University and Caltec Ltd, a company that provides engineering solutions to the oil and gas industry. The K-Shelf was developed using rapid web application development tool – Oracle APEX.

Keywords: set-based concurrent engineering, knowledge-shelf, design rationale, knowledge provision, product development, project summary report, service jet pump

WSEAS Transactions on Fluid Mechanics, ISSN / E-ISSN: 1790-5087 / 2224-347X, Volume 11, 2016, Art. #20, pp. 159-165

Title of the Paper: Stability of Dual Solutions in Boundary Layer Flow and Heat Transfer on a Moving Plate in a Copper-Water Nanofluid with Slip Effect

Authors: Norfifah Bachok, Najwa Najib, Norihan Md. Arifin, Norazak Senu

Abstract: An analysis is performed to study the flow and heat transfer characteristics on a moving plate in a nanofluid. The governing nonlinear differential equations are transformed into a system of nonlinear ordinary equations using a similarity transformation which is then solved numerically using a shooting method. While, for the stability analysis, the unsteady problem has to be introduced by introducing new dimensionless time variable which is then solved numerically using solver bvp4c. The numerical results are presented in tables and graphs for the skin friction coefficient and the local Nusselt number as well as the velocity and the temperature profile for a range of various parameters such as nanoparticles volume fraction, first order slip parameter and velocity ratio parameter. It is observed that the skin friction coefficient and the local Nusselt number which represents the heat transfer rate at the surface are significantly influenced by these parameters. The results indicate that dual solutions (first and second solutions) exist when the plate and free stream move in the opposite direction. A stability analysis has been performed to show which solutions are stable and physically realizable. Based on the analysis, the results indicate that the first solution is linearly stable, while the second solution is linearly unstable.

Keywords: Boundary layer flow, Heat transfer, Velocity slip, Nanofluid, Dual solutions, Stability analysis

WSEAS Transactions on Fluid Mechanics, ISSN / E-ISSN: 1790-5087 / 2224-347X, Volume 11, 2016, Art. #19, pp. 151-158

Title of the Paper: Velocity Fields in FGD Reactor by Different Flow Regimes

Authors: Jan Novosád, Petra Dančová, Tomáš Vít

Abstract: This article describes the gas flow inside the flue gas desulfurization (FGD) reactor. This reactor is self-constructed for using as experimental verification tool in research of modeling the desulfurization process. During the experimental study the velocity field at the inlet of the reactor and inside the spray zone were measured. Flow inside the FGD reactor could be modified by controlling power of the radial fan. This control is provided by frequency converter connected to the electric fan engine. For measuring of velocity Prandtl probe connected to TESTO 480 data logger is used. Obtained values of velocity at the inlet were used to set boundary conditions for CFD modelling. For CFD modelling the self-made modification of standard OpenFOAM solver is used. CAD model of the reactor was edited to the simplified geometry of fluid inside and several different computational meshes with different element size were created. After that CFD simulations were performed to study the effect of mesh size to results of simulations (velocity fields). These results are confronted with experimental data to assume the useful mesh. Whole process was made for two different flow regimes with 40% and 70% of maximal power of the fan. Based on the comparison the good agreement with the real state was found. The conclusion is that the mesh with generated elements could be used for further simulations.

Keywords: desulfurization, reactor, flow, velocity profile, CFD, OpenFOAM

WSEAS Transactions on Fluid Mechanics, ISSN / E-ISSN: 1790-5087 / 2224-347X, Volume 11, 2016, Art. #18, pp. 143-150

Title of the Paper: The Influence of Discontinuities on Waterflooding Process

Authors: Elena Andriyanova, Vladimir Astafev, Andrey Kasatkin

Abstract: The knowledge of the nature of fluid motion in the reservoir allows us to optimize a system of oilfield development. Thus, the study of filtration process in reservoirs with discontinuities, such as fractures, has a great importance for the oilfield development. For instance, the hydraulic fracturing is one of the most common recovery methods for unconventional reserves. The modern level of geophysics can show that most reservoirs have the tectonic faults of different permeability which have a great impact on well productivity. This article will show the impact of inclusions of different permeability in the reservoir on the waterflooding process. The steady-state flow process of incompressible fluid to the production well in a reservoir of constant height and permeability is considered. There is a thin area in the reservoir with constant permeability, which might be a highly permeable crack or low permeable barrier. The production and injection wells are placed inside the reservoir’s external boundary. The characteristics of waterflooding process are studied for various permeability values and different locations of a fracture and a pair of wells. Finally, the flow lines of the fluid flow will be analyzed for every considered case.

Keywords: waterflooding, hydraulic fracturing, Darcy flow, impermeable boundary, flow potential, streamlines

WSEAS Transactions on Fluid Mechanics, ISSN / E-ISSN: 1790-5087 / 2224-347X, Volume 11, 2016, Art. #17, pp. 134-142

Title of the Paper: Analytical Study of Finite Amplitude Capillary Waves Stability

Authors: Alexander Petrov, Mariana Lopushanski

Abstract: Using the Lyapunov method, we find analytically the equations of wave surface of capillary waves in fluid of infinite depth and compare them to the solution, obtained by Crapper. We prove analytically the stability of Crapper waves with respect to symmetric and non-symmetric disturbances.

Keywords: Direct Lyapunov method, capillary waves, Lyapunov function

WSEAS Transactions on Fluid Mechanics, ISSN / E-ISSN: 1790-5087 / 2224-347X, Volume 11, 2016, Art. #16, pp. 127-133

Title of the Paper: Parametric Study of a Microtab on a DU Airfoil

Authors: U. Fernandez-Gamiz, E. Zulueta, A. Boyano, B. Fernandez-Gauna

Abstract: A parametric study for design and analysis of a microtab (MT) on an airfoil is presented. These flow control devices consist of a small tab placed on the airfoil surface close to the trailing edge and perpendicular to the surface. Numerical simulations applied to this concept solve the governing Reynolds-averaged Navier-Stokes equations on structured mesh. The aim of the current study is to find the optimal position to increase airfoil aerodynamic performance, therefore a parametric study of a MT mounted on the pressure surface of an airfoil DU91W(2)250 has been carried out. This airfoil has been selected because it is typically used on multi megawatt wind turbines blades, such as the 5 MW wind turbine of the NREL. To that end, 2D computational simulations have been carried out at Re= 7.106. Procedure and best cases are presented.

Keywords: Microtab, Aerodynamics, Flow Control, Airfoil, Wind Turbine

WSEAS Transactions on Fluid Mechanics, ISSN / E-ISSN: 1790-5087 / 2224-347X, Volume 11, 2016, Art. #15, pp. 121-126

Title of the Paper: Binormal Evolution of Curves with Prescribed Velocity

Authors: O. J. Garay, A. Pampano

Abstract: At the end of the 19th century, Kirchhoff studied dynamical problems involving vortex flows of inviscid incompressible fluids focusing on flows having the shape of a vortex tube (vortex filaments). In 1906, Da Rios, a student of Levi-Civita, analyzed the motion of a vortex filament and obtained the remarkable equation describing its evolution, which, under mild conditions, is equivalent to the so called binormal evolution equation. Motivated by this, in this work we use fundamental facts of the theory of submanifolds to analyze the evolution of curves under binormal flows with curvature dependent velocity in pseudo-riemannian 3-space forms. The compatibility conditions for these systems are given by the Gauss-Codazzi equations, which here are expressed with respect to a geodesic coordinate system in terms of the Frenet curvatures of the evolving curves. Then, an existence result is derived from the Fundamental Theorem of submanifolds. Moreover, we show the connection between travelling wave solutions of the Gauss-Codazzi equations and the Frenet-Serret dynamics of curves. In fact, travelling wave solutions of the Gauss-Codazzi equations are shown to lead to the Euler-Lagrange equations of extremal curves for curvature dependent energies with a penalty on the total torsion and the length (generalized Kirchhoff centerlines). A characterization of generalized Kirchhoff centerlines in terms of Killing vector fields allows us to construct binormal evolution surfaces with prescribed velocity by using them as initial conditions for the evolution. Binormal surfaces obtained in this way evolve without change in shape. Finally, we particularize the previous findings to three significant cases which give rise to Hasimoto surfaces, Hopf tubes, and constant mean curvature surfaces.

Keywords: binormal flow, curve evolution, Frenet-Serret dynamics, extremal curves, submanifolds, real space forms

WSEAS Transactions on Fluid Mechanics, ISSN / E-ISSN: 1790-5087 / 2224-347X, Volume 11, 2016, Art. #14, pp. 112-120

Title of the Paper: Investigation on the Detection of Water Leaks in Small-Diameter Polyethylene Pipes Using Acoustic Emission Signals

Authors: Alberto Martini, Marco Troncossi, Alessandro Rivola

Abstract: Active control of water losses is an essential strategy to increase the efficiency of urban water supply systems. This work deals with the early detection of leaks occurring in small-diameter service pipes of water distribution networks. Preliminary experiments were conducted in a test facility to assess the sensitivity of Acoustic Emission methods to leaking water flows. Acoustic Emission measurements were performed on an unburied polyethylene pipe with artificially generated leaks. A good correlation between several monitored parameters and the characteristics of the examined leaks could be identified.

Keywords: Leak detection, Acoustic Emission, service pipe, water supply network

WSEAS Transactions on Fluid Mechanics, ISSN / E-ISSN: 1790-5087 / 2224-347X, Volume 11, 2016, Art. #13, pp. 106-111

Title of the Paper: Active Control of Axisymmetric Flow with Two Synthetic Jets Worked in Bifurcated Mode

Authors: Petra Dančová, Tomáš Vít, Darina Jašíková, Jan Novosád

Abstract: This paper deals with the experimental research of the effect of two synthetic jets worked in the bifurcated mode used for control of an axisymmetric air jet. First, the control synthetic jets were measured alone. After an adjustment, the primary axisymmetric jet was added in to the system. For comparison, the primary flow without synthetic jets control was also measured. All experiments were performed using PIV method whereby the synchronization between synthetic jets and PIV system was necessary to do. This work continues the investigation described in [11].

Keywords: Synthetic jet, primary flow, unforced flow, flow control, pulse modulation, PIV, synchronization

WSEAS Transactions on Fluid Mechanics, ISSN / E-ISSN: 1790-5087 / 2224-347X, Volume 11, 2016, Art. #12, pp. 98-105

Title of the Paper: Modelling and Design of Microflow Sensors Based on Measuring of Temperature

Authors: Milan Adamek, Michaela Barinova, Dora Lapkova

Abstract: The paper presents the design and experimental experience with the gas flow measurement instrument for the range of (5 – 25) ml/hr. The aimed application area is in a biochemical laboratory for the study of reaction kinetic of sediments decomposition in waste water. The time-of- flight type of sensor with one upstream and one downstream temperature sensor has been chosen for the study. We explain the basic operation principles of the tiny flow measurement and the sensor structure. In the numerical model paragraph, we are describing the basic configuration model and the modelling results. As the three-dimensional simulation would be very time consuming process, we have simplified the simulation for only two-dimensional task. The presented diagrams are derived for different gases (air, nitrogen, carbon oxide and chlorine) and sensor tube materials, namely steel, copper, and plexi-glass. We present also the experimental set-up including the design and sensor parameters. The paragraph with experimental results and discussion on them illustrates the good correspondence with expected values. The paper concludes with the employment of designed gas flowmeter in the biochemical laboratory.

Keywords: flow measurement, calorimetric sensor, time of flight, heating power, mass and heat transfer, Femlab, flow tube, flow range

WSEAS Transactions on Fluid Mechanics, ISSN / E-ISSN: 1790-5087 / 2224-347X, Volume 11, 2016, Art. #11, pp. 91-97

Title of the Paper: Adaptive Control of Fluid Inside CSTR Using Continuous-Time and Discrete-Time Identification Model and Different Control Configurations

Authors: Jiri Vojtesek, Petr Dostal

Abstract: An adaptive control is a kind of modern control methods with great theoretical background and various modifications. This control approach could be used for system with negative control properties such as nonlinearity, non-minimum phase behaviour etc. The adaptive control in this paper is based on the recursive identification of the external linear model as a linear representation of the originally nonlinear system. The control synthesis is based on the polynomial approach together with the spectral factorization and the pole-placement method. The identification model in the continuous-time uses differential filters and so called delta-models in the discrete-time. There were tested also two types of control configurations with the one degree-of-freedom (1DOF) that has controller only in the feedback part and with the two degrees-of-freedom (2DOF) where the controller is separated into two parts the first is in the feedback and the second is feedforward part of the control loop. Paper shows usability of this control approach by the simulations on the mathematical model of the continuous stirred-tank reactor with the cooling in the jacket as a typical nonlinear system with lumped parameters.

Keywords: Simulation, Mathematical Model, Adaptive control, Continuous-time model, Delta-model, Continuous Stirred-tank Reactor, 1DOF, 2DOF

WSEAS Transactions on Fluid Mechanics, ISSN / E-ISSN: 1790-5087 / 2224-347X, Volume 11, 2016, Art. #10, pp. 81-90

Title of the Paper: Unsteady MHD Second Grade Fluids Flow in a Porous Medium with Ramped Wall Temperature

Authors: Zulkhibri Ismail, Ahmad Qushairi Mohamad, Ilyas Khan, Sharidan Shafie

Abstract: In this paper, the unsteady MHD flow of second grade fluids in a porous medium are analyzed. It is assumed that the bounding infinite inclined plate has a ramped wall temperature with the presence of heat and mass diffusion. Closed-form solutions in a general form are obtained by using the Laplace transform technique. The obtained results for velocity is found to satisfy all the imposed initial and boundary conditions. It can be reduced to known solutions from the literature as limiting cases.

Keywords: Double diffusion, MHD, Porous medium, Inclined plate, Second grade fluids, Laplace transform

WSEAS Transactions on Fluid Mechanics, ISSN / E-ISSN: 1790-5087 / 2224-347X, Volume 11, 2016, Art. #9, pp. 76-80

Title of the Paper: Effect of Liquid Density on Particulate Flow in Dam Break

Authors: Gyeong Min Park, Hyun Sik Yoon, Min Il Kim

Abstract: The present study invetigated the dam breaking containg the particles by handling three pahses of the lquid-gas-solid mixure. The discrete element method (DEM) - computational fluid dynamics (CFD) conbined methos was adopted to resolve the three pahses of the lquid-gas-solid mixure. The present study considers the wide range of the liquid density to investugate the effect of the liquid density on the behavior of the particles and the free-surface. Three regimes of the overlapping, divergent and impinging behaviors govern the time evolution of the particles and the free-surface. The overlapping regime shows that the front head positions of the liquid and the particles are almost identical and two dimensional behaviors. However, in the divergent regime, lower liquid densities derive that the liquid front head is faster than that of the particle. Over the critical liquid density, the opposite divergent pattern to the low liquid density appears. Especially, the three-dimension effect on the distribution of the particles and the free-surface appears in the divergent regime.

Keywords: DEM, CFD, Three pahses, Lquid-gas-solid mixure, Three regimes

WSEAS Transactions on Fluid Mechanics, ISSN / E-ISSN: 1790-5087 / 2224-347X, Volume 11, 2016, Art. #8, pp. 69-75

Title of the Paper: Definition of Critical Hydrodynamic Conditions for Sediment Motion Initiation Using Optical Techniques

Authors: Juan Antonio García Aragón, Klever Izquierdo Ayala, Humberto Salinas Tapia, Carlos Díaz Delgado

Abstract: Sediment motion initiation experiments were performed in a glass rectangular channel, with a loose bed in the central part. The main goal is to obtain the critical hydrodynamic characteristics that causes sediment bed motion initiation, for different cohesionless sediment grain sizes. The optical technique of Particle Tracking Velocimetry (PTV) was used in order to determine the critical velocity profiles for sediment initiation of motion. Between the parameters that define this critical velocity profile is the one known as bed rugosity which represents the height of asperities in the bed. For conditions near bed motion initiation experimental velocity profiles were obtained and they allowed us also to define fluctuating velocities u?, v? and a value of bed rugosity ks related to a representative grain size of the bed. It was shown that obtained critical velocity profiles are in good agreement with other works in the scientific literature provided an appropriate definition of bed rugosity is made.

Keywords: non-cohesive sediments, motion initiation, bed rugosity, critical velocity profile, PTV

WSEAS Transactions on Fluid Mechanics, ISSN / E-ISSN: 1790-5087 / 2224-347X, Volume 11, 2016, Art. #7, pp. 57-68

Title of the Paper: Study on Contact State and Contact Stress Distribution of Kettle Mechanical Seal

Authors: Shuangxi Li, Huanli, Kesong Huang, Qiuxiang Zhang, Jining Cai

Abstract: In traditional mechanical seal design, the average transverse stress is used. However, in practice, the distribution of seal face contact tress is not uniform. The contact state and contact stress distribution affect seal face’s state of wear and deformations, which are of vital to the sealability and sealing life. Therefore, in this paper, complete and accurate finite element models of kettle mechanical seal (KMS) rotator ring, stator ring and stator ring seat were established by ANSYS. The seal face contact state and the contact stress distribution were obtained by the finite element analysis. And the influence laws of working pressure P, stator ring height H, load coefficient K, stator ring auxiliary O-ring inner diameter ratio S, etc. on the face performance were analyzed. It was shown that the contact stress distribution may be non-uniform in higher working pressure condition. Besides, the higher the working pressure P was, the more non-uniform the distribution was and the smaller the contact area was. The contact stress distribution was more uniform, the contact area increased and the maximum seal face contact stress decreased with the increasing of H, K and S. The research results were verified by designed test and provide a theoretical basis for the design and optimization of mechanical seal.

Keywords: kettle mechanical seal, contact stress distribution, contact state

WSEAS Transactions on Fluid Mechanics, ISSN / E-ISSN: 1790-5087 / 2224-347X, Volume 11, 2016, Art. #6, pp. 49-56

Title of the Paper: Thermal Simulation of the Effect of Windings Arrangement in a Cooled Power Transformer

Authors: Alejandro Roberto Tello Campos, William Vicente Rodríguez, José Luis Fernández Zayas, Ignacio Carvajal Mariscal, Rodrigo Ocon Valdez

Abstract: The outcome of the study will be the determination of the effects of modifying geometrical parameters of a real 33.6 MVA power transformer by means of a simplified model based on CFD methods. This will help the designers to prove that power transformers winding physical arrangements determine the location and value of critical temperatures such as the hot spot. Basically, the results show that a the proposed variations in the outer radius of the high voltage winding and the high and low voltage vertical cooling duct widths do affect the critical temperatures location and value due to oil hydrodynamics. Results show that there is a reduction of 3.21% and 1.34% in the value of critical temperatures for the HV and LV cooling duct variation respectively and the location of hot spot is more specifically defined at the 42th LV disc. Outer HV radius variation results show also an increase of 1.6% in critical temperature and the location of hot spot still remains in the 42th LV disc.

Keywords: Power transformer, mixed convection, CFD, thermal simulation, geometrical parameters

WSEAS Transactions on Fluid Mechanics, ISSN / E-ISSN: 1790-5087 / 2224-347X, Volume 11, 2016, Art. #5, pp. 36-48

Title of the Paper: Fluid Filled Containments Impact by a High Velocity Bullet

Authors: Smirnova M. N., Kondrat’ev K. A.

Abstract: High velocity fragment or bullet interaction with thin walled fluid-filled containment is investigated. Fragment subsonic motion in compressible fluid was studied being the function of the depth of perforation under the water level in case the containment was partially filled with water and partially with gas having a distinct fluid-gas interface. Approximation formulas were developed making it possible to simulate resistance and drag forces being functions of governing parameters. The developed models were validated by comparing theoretical data with results of experiments. The obtained solutions are applicable for developing concepts for effective shield design protecting from high velocity fragments.

Keywords: fragment, impact, crater, fluid-filled containment, resistance force, perforation

WSEAS Transactions on Fluid Mechanics, ISSN / E-ISSN: 1790-5087 / 2224-347X, Volume 11, 2016, Art. #4, pp. 25-35

Title of the Paper: Regulation Performance of Regulatable Dry Gas Seal

Authors: Shuangxi Li, Qiaofeng Zhu, Jining Cai, Qiuxiang Zhang, Zhaoxu Jin

Abstract: It is important for the regulatory efficiency and the popularization of R-DGS to study on the regulation performance of a Regulatable Dry Gas Seal (R-DGS). Based on gas lubrication theory, a numerical model for R-DGS was set up, the Steady Reynold equation and Disturbance Reynold equation were resolved by using finite element method to obtain the equilibrium film thickness, leakage rate and dynamic parameters. The universal law of the seal parameters was obtained under difference regulation ratio Γ and shaft speed. The running regulation test is processed and the regulation reliability of R-DGS with outer regulative gas source is proved. The results show that the sealing performance of R-DGS changes obviously with the regulation ratio (Γ); and the shaft speed also effect the sealing performance when the regulation ratio is Γ<1.5. Comprehensive regulation performance of Pi-DGS is better than Po-DGS. The research results verify the feasibility of R-DGS and provide a reference for user to design and regulatory the R-DGS.

Keywords: Regulatable dry gas seal, Regulation performance, Steady state, Disturbed State

WSEAS Transactions on Fluid Mechanics, ISSN / E-ISSN: 1790-5087 / 2224-347X, Volume 11, 2016, Art. #3, pp. 18-24

Title of the Paper: The Influence of the Reservoir Discontinuities on Fluid Filtration to the Production Well

Authors: Elena Andriyanova, Vladimir Astafev

Abstract: Today especially important to study the filtration process in the reservoir with fractures. The fracture may be either natural, in case of tectonic fault, or artificial, in case of well simulation, and it may have various permeability values. This paper considers the steady-state flow process of incompressible fluid to the production well in a reservoir of constant height and permeability. There is a thin area in the reservoir with constant permeability kf, which might be highly permeable crack or low permeable barrier. The characteristics of filtration process are studied for various kf values. The nature of fluid flow to the wellbore is analyzed at different locations of the well and the crack for different values of the fracture conductivity in this paper and the analytical expression for skin effect is defined.

Keywords: filtration, skin effect, highly permeable cracks, hydraulic fractures, low permeable barriers, Darcy flow, flow potential

WSEAS Transactions on Fluid Mechanics, ISSN / E-ISSN: 1790-5087 / 2224-347X, Volume 11, 2016, Art. #2, pp. 10-17

Title of the Paper: Computational Investigation of the External Excitation Frequency Effect on Liquid Sloshing Phenomenon

Authors: Abdallah Bouabidi, Zied Driss, Nihed Cherif, Mohamed Salah Abid

Abstract: In this work, the Computational Fluid Dynamic (CFD) method was used to simulate the liquid sloshing phenomenon in a rectangular tank. The tank was subjected to an external sinusoidal excitation. Particularly, we are interested on the study of the external excitation frequency effect. The hydrodynamic parameters describing the flow like the velocity field, the average velocity, the static and the dynamic pressure were presented. All numerical results were conducted using the commercial CFD code "FLUENT". The volume of fluid (VOF) method based on the finite volume method was used to simulate incompressible viscous two phase flow in a tank partially filled with liquid. The results show that the liquid sloshing significantly depends on the frequency value. For a weak value of frequency, the liquid moves slowly. With the increase of the frequency, the liquid sloshing becomes more violent. A good agreement has been shown by comparing our numerical results with the experimental one.

Keywords: External excitation, frequency, turbulent flow, finite volume method, VOF

WSEAS Transactions on Fluid Mechanics, ISSN / E-ISSN: 1790-5087 / 2224-347X, Volume 11, 2016, Art. #1, pp. 1-9

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