CFD SIMULATION OF EROSION BY PARTICLE COLLISION IN U-BEND AND HELICAL TYPE PIPES

Erosion caused by solid particles in curve pipes is one of the major concerns in the oil and gas industries. Small solid particles flow with a carrier liquid fluid and impact the inner wall of the piping, valves, and other equipment. These components face a high risk of solid particle erosion due to the constant collision, which may result in equipment malfunctioning and even failure. In this study, the two-way coupled Eulerian-Lagrangian method with the Oka erosion and Grant and Tabakoff particle-wall rebound models approach is employed to simulate the liquid-solid flow in U-bend and helical pipes using computational fluid dynamics. The effects of operating parameters (inlet fluid velocity and temperature, particle density and diameter, and mass flow rate) and design parameters (mean curvature radius/pipe diameter ratio) are investigated on the erosion of these tubes walls. It is obtained that increasing the fluid velocity and temperature, particle mass flow and particle density increase the penetration rate, particle diameter affects the rate of penetration, and increasing mean curvature radius/pipe diameter ratio decreases the rate of penetration.

THREE-DIMENSIONAL SIMULATION OF A SMALL-SCALE ELECTRODIALYSIS PROCESS FOR DOMESTIC USE

The hydrodynamic by MHD driving force and ionic transport characteristics of an electrolytic solution in a small-scale electrodialysis process are taken into account in this new approach. A three-Dimensional modeling and simulation of coupling Magnetohydrodynamic-Ionic transport are carried out. The numerical values and the effects of applied voltage and magnetic induction on the fluid velocity and ionic concentration of species present in the solution are displayed graphically. The results show that a high decrease of ion concentration is achieved and suggest that the proposed model which has no moving parts can be practically implemented.

NUMERICAL SIMULATION OF ENTROPY GENERATION FOR CASSON FLUID FLOW THROUGH PERMEABLE WALLS AND CONVECTIVE HEATING WITH THERMAL RADIATION EFFECT

In this work, the influence of entropy generation analysis for an electrically conducting Casson fluid flow with convective boundary conditions has been numerically studied. The governing equations are analyzed numerically using weighted residual methods. Subsequently, the residuals were minimized using two different approaches of weighted residual method namely collocation weighted residual method (CWRM) and Galerkin weighted residual method (GWRM) and computed numerically using MATHEMATICAL software. The impacts of governing parameters on Casson flow velocity, temperature profile, local skin friction, and Nusselt number were analysed. The obtained solutions were used to determine the heat transfer irreversibility and bejan number of the model. The results of the computation show that the effect of thermophysical properties such as thermal radiation parameter, suction/injection parameter, magnetic field parameter, radiation parameter, and Eckert number has a significant influence on Skin friction coefficient (Cf) and local Nusselt number (Nu) when compared to the Newtonian fluid. The findings from this study are relevant to advances in viscoelasticity and enhanced oil recovery.

NUMERICAL SOLUTIONS OF THE NONLINEAR POROUS MEDIA EQUATION BASED ON HIGH EXPLORATION PARTICLE SWARM OPTIMIZATION AND MOVING LEAST SQUARES

In this study, a new numerical method based on the combination of High Exploration Particle Swarm Optimization (HEPSO) and Moving Least Squares (MLS) is introduced to solve nonlinear porous media equations. The MLS scheme is employed to describe an appropriate discretized function, and the penalty method is implemented to convert the constrained problem into an unconstrained one via satisfying the initial conditions. The identified objective function is minimized by the HEPSO to find the approximated nodal values for the nonlinear porous media equation. In order to illustrate the effectiveness of the HEPSO, the optimization trajectories are compared with those of a Standard Particle Swarm Optimization (SPSO) algorithm. Moreover, comparisons are made between the exact solution and the introduced strategy to expose the accuracy, effectiveness and simplicity of the proposed method.

MAGNETIC FLUID-BASED SQUEEZE FILM BETWEEN CURVED POROUS ANNULAR PLATES CONSIDERING THE ROTATION OF MAGNETIC PARTICLES AND SLIP VELOCITY

The ferrofluid flow model of the Shliomis and continuity equation for the film and porous interface with the theory of Darcy, the modified Reynolds equation for ferrofluid squeeze film between curved annular plates is discussed with the impact of the rotation of Ferro-particles and slip velocity at the boundary. Beavers and Joseph’s slip conditions are adopted to study the impact of slip velocity. The generalized non-dimensional pressure equation is derived and expression for dimensionless load-carrying capacity is obtained for the same. The graphical representation suggests that the bearing's performance enhances due to ferrofluid, considering the appropriate values of parameters for slip velocity and porosity.

INTERFERENCE OF CLOSABLE CRACKS AND NARROW SLITS IN AN ELASTIC PLATE UNDER BENDING

The problem of bending of an infinite plate containing an array of trough closable cracks and narrow slits is considered in a two-dimensional statement. A crack is treated as a mathematical cut, the edges of which are able to contact along the line on the plate outside. A slit is referred to as a cut with contact stress-free surfaces and the negative jump of normal displacement can occur on this cut. The crack closure caused by bending deformation was studied based on the classical hypothesis of direct normal and previously developed model of the contact of edges along the line. A new boundary problem for a couple of biharmonic equations of plane stress and plate bending with interconnected boundary conditions in the form of inequalities on the cuts is formulated. The method of singular integral equations was applied in order to develop approximate analytical and numerical solutions to the problem. The forces and moments intensity factors near the peaks of defects and contact reaction on the closed edges of the cracks are calculated. A detailed analysis was carried out for parallel rectilinear crack and slit, depending on their relative location. Presented results demonstrate qualitative differences in the stress concentration near the defects of different nature.

INVESTIGATING POSSIBILITIES OF CRACK INITIATION LIFE EXTENSION IN JET ENGINES COMPRESSOR DISKS

This paper deals with jet engines compressor disks which have dovetail joints with blades. A compressor disk with reduced fatigue resistance was taken as an example. Two simplified conceptual solutions of the dovetail joint with blades were devised. Based on the low cycle fatigue theory, the crack initiation life of their critical parts with newly-proposed transition rounding at the bottom of dovetail grooves was estimated. Two different flank angles in the dovetail grooves (60° in the critical part that belongs to the first dovetail joint conceptual solution and 55° in the critical part that belongs to the second dovetail joint conceptual solution), two different aviation steels selected for workmanship (13H11N2V2MF and AISI 304 steel) and two load histories (load history LH1 and load history LH2), were taken into account. By load history LH2 an overload of the critical parts was simulated. The results of crack initiation life estimation of the critical parts in the dovetail joint conceptual solutions show that there is a possibility for the crack initiation life extension of the observed compressor disk. In all analyzed variants, it has been shown that the critical part in the second dovetail joint conceptual solution has longer crack initiation life than the critical part in the first dovetail joint conceptual solution. For example, the critical part in the second dovetail joint conceptual solution made of AISI 304 steel, in the case of load history LH1 has 141.55% longer crack initiation life than the critical part in the first dovetail joint conceptual solution made of 13H11N2V2MF steel. In the case of load history LH2 (an overload case) that percent is greater and amounts to 173.15%.

HYDRODYNAMIC ANALYSES OF THE FLOW PATTERNS IN STIRRED VESSEL OF TWO-BLADED IMPELLER

In this paper, the governing equations of continuity and momentum subjected to suitable boundary conditions have been solved numerically to investigate the fluid flow in stirred vessel of two-bladed impeller. The numerical simulations have been carried out in three-dimensions for laminar flow. The studied fluid was considered Newtonian and incompressible. Our research studied the effects of geometrical configurations of the two-bladed impeller and its rotational speed on fluid patterns and mechanical power consumption. The innovative point in this paper is that the blades of the impeller contain three equal-sized holes of circular cross-section. The diameter of the hole (d) to the impeller diameter (D) gives the ratio d/D. the impeller speed is controlled by the Reynolds number (Re). The obtained results have been illustrated and discussed for the range of following governing parameters: d/D = 0 to 0.4 and Re = 1 to 300. The results showed that the studied parameters have significant effects on fluid flow and consumption power and the perforated blades of ratio d/D = 0.133 is more efficient than plan blades. Also, a new correlation is proposed to describe the consumption power as function of d/D and Re.

BIOMECHANICAL BEHAVIOUR OF THE TOTAL HIP PROSTHESIS SUBJECTED TO NORMAL GAIT CYCLE LOAD: IDENTIFICATION OF THE DAMAGE IN THE CEMENT MANTLE

Cement is the weakest link in the composition of total hip prosthesis in terms of mechanical properties. The knowledge of the intensity and distribution of stresses on the cement attaching the implant to the bone is of great importance for understanding the condition of the prosthesis and its failure. In this study, the finite element method is used to analyze the magnitude and the equivalent Von Mises stress distribution induced in different components of the total hip prosthesis (THP) as well as the identification of the damage induced in the cement and between two cavities located in the polymethyl methacrylate (PMMA). The crack propagation is determined and localized using the extended element method (XFEM). The results show that the fracture stress of the cement in its proximal part is very important. These stresses increase considerably with the interaction of the cavities in this binder, causing damage to the cement and the loosening of the prosthesis.

ANALYSIS OF ENTROPY GENERATION FOR MIXED CONVECTION FLUID FLOW IN A TRAPEZOIDAL ENCLOSURE USING THE MODIFIED BLOCKED REGION METHOD

In this research, analysis of entropy generation for mixed convection fluid flow in a trapezoidal enclosure is numerically investigated. To achieve this goal, the influences of Grashof number, Reynolds number and inclination angle of enclosure side walls on the distributions of the velocity and temperature fields and the values of entropy generation and Bejan numbers are examined with full details. The Boussinesq approximation is used to calculate the buoyancy force. Also, the entropy generation numbers are calculated according to the second law of thermodynamics. In addition, the modified blocked region method is applied to accurately simulate the diagonal walls of the trapezoidal enclosure. The results of numerical solution show that the maximum values of the flow irreversibility in the whole computational domain of the enclosure are related to the case with the highest values of Grashof number, Reynolds number and inclination angle of side walls.