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This paper aims to adopt incompressible smoothed particle hydrodynamics (ISPH) method for studying magnetohydrodynamic (MHD) double-diffusive natural convection from an…
This paper aims to adopt incompressible smoothed particle hydrodynamics (ISPH) method for studying magnetohydrodynamic (MHD) double-diffusive natural convection from an inner open pipe in a cavity filled with a nanofluid.
The Lagrangian description of the governing equations was solved using the current ISPH method. The effects of two pipe shapes as a straight pipe and V-pipe, length of the pipe LPipe (0.2-0.8), length of V-pipe LV (0.04-0.32), Hartmann parameter Ha (40-120), solid volume fraction ϕ (0-0.1) and Lewis number Le (1-50) on the heat and mass transfer of nanofluid have been investigated.
The results demonstrate that the average Nusselt and Sherwood numbers are increased by increment on the straight-pipe length, V-pipe length, Hartmann parameter, solid volume fraction and Lewis number. In addition, the variation on the open pipe shapes gives a suitable choice for enhancement heat and mass transfer inside the cavity. The control parameters of the open pipes can enhance the heat and mass transfer inside a cavity. In addition, the variation on the open pipe shapes gives a suitable choice for enhancement heat and mass transfer inside the cavity.
ISPH method is developed to study the MHD double-diffusive natural convection from the novel shapes of the inner heated open pipes inside a cavity including straight-pipe and V-pipe shapes.
This paper aims to adopt incompressible smoothed particle hydrodynamics (ISPH) method to simulate MHD double-diffusive natural convection in a cavity containing an…
This paper aims to adopt incompressible smoothed particle hydrodynamics (ISPH) method to simulate MHD double-diffusive natural convection in a cavity containing an oscillating pipe and filled with nanofluid.
The Lagrangian description of the governing partial differential equations are solved numerically using improved ISPH method. The inner oscillating pipe is divided into two different pipes as an open and a closed pipe. The sidewalls of the cavity are cooled with a lower concentration C_c and the horizontal walls are adiabatic. The inner pipe is heated with higher concentration C_h. The analysis has been conducted for the two different cases of inner oscillating pipes under the effects of wide range of governing parameters.
It is found that a suitable oscillating pipe makes a well convective transport inside a cavity. Presence of the oscillating pipe has effects on the heat and mass transfer and fluid intensity inside a cavity. Hartman parameter suppresses the velocity and weakens the maximum values of the stream function. An increase on Hartman, Lewis and solid volume fraction parameters leads to an increase on average Nusselt number on an oscillating pipe and left cavity wall. Average Sherwood number on an oscillating pipe and left cavity wall decreases as Hartman parameter increases.
The main objective of this work is to study the MHD double-diffusive natural convection of a nanofluid in a square cavity containing an oscillating pipe using improved ISPH method.
Simulation and analysis of a real main steam line break transient at theThermal Power Plant Drmno are presented. The main events of the transientwere the closure of…
Simulation and analysis of a real main steam line break transient at the Thermal Power Plant Drmno are presented. The main events of the transient were the closure of isolation valves in front of a high pressure turbine, an opening of a by‐pass line, and subsequent pipe break in front of isolation valves. Intensive pressure waves were generated and they propagated through the pipe network of the steam line, causing high fluid dynamic forces on the structure. The transient has been simulated by the computer code TEA‐01, based on the Method Of Characteristics with three characteristic directions. Several main steam line boundary conditions have been modelled and verified. Numerical results are compared with plant data logger records. Simulation has been performed for various scenarios in order to investigate the plant behaviour sensitivity on the boundary conditions. The phenomenology of the pressure waves propagation and the influence of the boundary conditions on these processes are described in detail, as well as fluid dynamic forces during the closure of isolation valves and subsequent pipe break in a section of the steam line in the vicinity of the pipe break.
In a constant speed, variable pitch propeller an over‐ride device is automatically brought into operation to move the blades to the feathering position when the power unit stops, and means are provided by which the over‐ride is automatically put out of action when an attempt is made to start the power unit by ‘wind‐milling’, and by which the over‐ride is automatically restored when the speed rises to that at which the unit should be self‐operating. When the power unit stops a governor 23 allows a spring 22 to force a valve 19 to the left, thereby allowing motive fluid from a pipe 12 to flow into the left‐hand end of a cylinder 16 to operate a plunger 15 which moves the propeller blades 13 to the minimum pitch position. The resultant change of torque acting on a torque meter 39 closes a switch 37 to complete an electrical circuit for actuating a solenoid 35 controlling a valve 34 which allows motive fluid to be applied from pipe 31 to the spring‐loaded plunger 28 of the over‐ride device. The plunger moves the valve 19 to the right, allowing fluid into the right‐hand end of cylinder 16, thereby moving the blades to the feathering poistion. The circuit may also be completed by the pilot closing the fuel isolator valve 36. To start the power unti by wind‐milling, ignition switch 46 of the power unit is closed, the govenor controlled switch 47 being already closed. A solenoid 45 then opens a switch 44 and breaks the circuit to the solenoid 35 so that the valve 34 closes to cut‐off the supply of fluid to the over‐ride plunger. The spring 22 is thus able to move the valve 19 to the left with the result that the blades are moved from the feathered position to cause ‘wind‐milling’. If at a predetermined speed the unit does not then become self‐operating, its governor will open the switch 47 causing switch 44 to close to complete the circuit to the solenoid 35. The valve 34 will be raised to bring the over‐ride into operation, causing plunger 28 to move valve 19 so that the propeller blades are moved to the feathered position.
This paper proposes a decision‐making framework to assist asset managers in decision making regarding sewer maintenance/rehabilitation (M&R) plans under constraints of…
This paper proposes a decision‐making framework to assist asset managers in decision making regarding sewer maintenance/rehabilitation (M&R) plans under constraints of limited access to sewer condition data. It discusses the application of probabilistic dynamic programming in conjunction with a Markov chain model to analyze the life cycle cost of combined sewer systems. M&R issues have traditionally been addressed with a crisis‐based approach, but this study contributes to sewer infrastructure management efforts in developing a management system based on life cycle cost analysis. The framework includes the optimal M&R techniques for sewer projects and the optimal times of application. The role of simulation is also explored to obtain the variability of the total cost. By knowing the expected costs and their variabilities, a deeper understanding of life cycle costs of sewer infrastructure can be obtained. The model’s capability is enhanced further by testing its sensivitity to varying discount and inflation rates.
An infinite element based on the doubly asymptotic approximation (DAA) for use in finite element analysis of fluid—structure interactions is presented. Fluid finite…
An infinite element based on the doubly asymptotic approximation (DAA) for use in finite element analysis of fluid—structure interactions is presented. Fluid finite elements model the region near the solid. Infinite elements account for the effects of the outer fluid on the inner region. The DAA‐based infinite elements involve an approximate calculation of the added mass using static mapped infinite elements, plus a consistent damping term. Simple test analyses for a range of fluid properties demonstrate the performance of the solution technique. The analyses of a Helmholtz resonator (open pipe) and a circular plate in water indicate the practical use of the solution approach.
An advanced heat transfer model for both unlooped and looped Pulsating Heat Pipes (PHPs) with multiple liquid slugs and vapor plugs has been developed. The thin film…
An advanced heat transfer model for both unlooped and looped Pulsating Heat Pipes (PHPs) with multiple liquid slugs and vapor plugs has been developed. The thin film evaporation and condensation models have been incorporated with the model to predict the behavior of vapor plugs and liquid slugs in the PHP. The results show that heat transfer in both looped and unlooped PHPs is due mainly to the exchange of sensible heat. Higher surface tension results in a slight increase in the total heat transfer. The diameter, heating wall temperature, and charging ratio have significant effects on the performance of the PHP. Total heat transfer significantly decreased with a decrease in the heating wall temperature. Increasing the diameter of the tube resulted in higher total heat transfer. The results also showed that the PHP could not operate for higher charge ratios.
The basic parameters of screen printing are discussed, and an analytical model of the screen printing process is introduced. The ink roll in front of the squeegee is…
The basic parameters of screen printing are discussed, and an analytical model of the screen printing process is introduced. The ink roll in front of the squeegee is treated as a pump generating, close to the squeegee edge, high hydrostatic pressure which injects ink into the screen meshes. The shearing of the ink, the mechanics of screen snap‐off and the ink transfer taking place behind the squeegee are also analysed.
In an arrangement for deflecting a propulsive jet forwardly for braking purposes the jet reversal is effected by moving a series of curved blades at the rear end of the jet pipe to intercept the jet stream. As shown in FIG. 1 the jet pipe 10 terminates in an opening in the upper surface 12 of a delta‐wing, the deflecting blades 17 being mounted to form a grille 14 which is normally housed forwardly of the jet discharge opening, but which is movable rearwardly by an electric motor 33 and rack‐and‐pinion gearing 27, 28 into a position where it extends across the discharge opening to reverse the jet. FIG. 2 shows a modification in which the jet is divided into two streams by a wedge shaped vane 109 to discharge through openings 107, 108 in the upper and lower wing surfaces respectively, deflexion of the streams being effected by upper and lower grilles 102, 103. In addition the vane 109 may be rotated about a pivot 140 to deflect the whole of the jet through the upper or lower wing outlet. A similar effect may be obtained without the use of a bifurcated jet pipe by modifying the arrangement according to FIG. 1 to include a downwardly directed branch of the jet pipe 10 opening in the undersurface of the wing and controlling the flow of the jet through this branch by hinged flaps at the junction of the main and branch pipes, and in the undersurface of the wing, respectively. In the case of a circular jet pipe 40, FIG 3, the rear portion of the pipe is cut off along oblique planes 41, 42, and the cut‐away portions occupied by curved vanes 43, 44 hinged about a rear transverse axis 45. The vanes 43, 44 are surrounded by curved blade grills 46, 47 which in turn are enclosed by external plates 51, 52. To effect reversal of the jet the closure plates 51, 52 are first slid forwardly clear of the grilles 46, 47, and jacks 55, 56 are then operated to move the grilles 46, 47 and the tail portion 53 of the jet pipe forwardly, thus causing the vanes 41, 42 to pivot about the axis 45 to obstruct the jet pipe and cause the jet to escape through the grilles 46, 47.