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Go to Editorial ManagerA wind tunnel is a piece of equipment specifically designed for studying the influence of air passing over solid matters in aerodynamic research. Computational Fluid Dynamics (CFD) was used to conduct methodical research into the design and modeling of flow characteristic in a closed-loop wind tunnel. The necessary intake fan velocity was established using an analytical velocity model, and the test section's inlet conditions were produced by applying the Reynolds number equation, assuming that the Reynolds number was 500,000. Instead than using the traditional method, a full-scale CFD model of the complete wind tunnel was taken into consideration. This made it possible to improve the flow quality over the entire circuit as well as only in the test area. The test section flow quality was more impacted by upstream flow circumstances than downstream conditions, according to analysis of the guide vane designs. Therefore, careful consideration has to be done while constructing the vanes at upstream curves, especially corners that are parallel to the test section. The simulation results showed that, in the case of a fully configured wind tunnel, flow uniformity in the test section is successfully attained.
The Atmospheric Water Generator (AWG) is an environmental water recovery that easily dehumidifies water vapor moisture from the air. This article presents an experiment to construct an AWG model using solar energy as a source of power. An experimental and numerical study for a device of (AWG) is performed. The experimental work is performed at Basrah city, located in the south of Iraq, during August and September of 2019 and March of 2020. The theoretical results are calculated by EES and the numerical study has been conducted by the (ANSYS19/CFD/ FLUENT) program. The experimental device is tested for different days with different climate conditions. The Maximum water production obtained is 3.4 L/day from all the testing days, for different hours of operation when the relative humidity in the range of (45 – 95 %) and the temperature range from 17 °C to 45 °C. The results shown that, the water production rate is increased with increasing humidity, temperatures, hours of operation, and model size.
The flow control around the airfoil is widely investigated and utilized in the aircraft industry. The benefit of reducing the separation effect and its impact on the aerodynamic performance made the effort on this area is more desirable as this will impact to enhance the flight control as well as to reduce the fuel consumption during the flight. In this paper, the flow control using leading-edge blowing technique has been conducted for NACA0018 airfoil at Reynolds number 6.85 and 13.7 × 10 5 . A CFD analysis has been conducted to examine several flight parameters and blowing speed to explore the benefit of using the blowing in this wing section. The results indicate that the lift coefficient can be enhanced to be increased by 4-6% as compared with no blowing case. However, this increase ratio is affected by the operational Reynolds number and blowing ratio. Higher speed means less benefit from blowing within the limit of blowing ratio of 1. The benefit of using the blowing could come with an increase in the drag at some angle of attack. It is noticed that the blowing technique can generate positive pitching moment at lower angle of attack and can reduce the negative moment when the separation is happening at higher angle of attack. Also, the lesson learned in this paper is that the blowing benefit is more pronounced when the flight is under low Reynolds number environment.
A numerical simulation of the effect evaluation of heat loss and temperature distribution along the wellbore is performed, for two models, the first is an open hole (without perforation) and the other is a perforated vertical wellbore. In this study, the Computational Fluid Dynamics (CFD) software code ANSYS FLUENT 15.0 has been used, for simulate a model of 3-D turbulent flow with stander k-ϵ model. The results of this show that, increasing the heat losses leads to an increase in the temperature gradient, while the temperature gradient decreases with increasing inlet main velocity. Also, the temperature of the produced crude oil decreases with increasing the length of the wellbore.
Several geometrical elements influence the aerodynamic properties of the Darrieus vertical axis wind turbines (VAWTs). Many extant studies have examined properties, such as solidity, pitching axis position ( x /c), length of chord (c), blade quantity (N), diameter (d) of the rotor, and aspect ratio. However, not many have examined the shape of the airfoil (AF), which is a vital property that remains to be thoroughly investigated. Therefore, this present study used computational fluid dynamics (CFD) to investigate many airfoils blade characteristics, such as blade thickness (BT), maximum camber ratio (MCR), MCR location (MCRL), and air speed (AS), to determine their impact on VAWT performance. The results demonstrate a blade thickness BT of 10 to 12%, MCR of 0 to 22%, and MCRL of 24 to 23% yield a comparatively high coefficient of power, adequate optimal blade rotation to airspeed ratio (TSR), broader operational area, and high band efficiency while air velocities of 15 to 10% yield a comparatively higher power coefficient.
In this paper, computation fluid dynamics model (CFD) is used to simulate a turbulence flow fields along the jet ejector. A Steady-state 2-D compressible flow model utilities the standard k- turbulent model has been used. The performance of jet ejector is simulated by FLUENT 6.3 (code) and GAMBIT software, using finite-volume scheme to solve transport NAVIER STOKE equations. The objective of this study is to investigate the high- performance of jet ejector geometry (mass flow and head ratio) nozzle to throat diameter at eight cases (DN/DT) with different initial pressure. Research is performed to optimize jet performance by varying initial pressure and nozzle diameter ratios from (1/8) to (8/8). To increase understanding of the axial velocity distribution at an important regions along the ejector, three regions are chosen, at inlet (1,3), nozzle exit(2) and midpoint of throat(4), with an important different diameters ratio cases 1,2,3,5,7 and 8 respectivly. The comparison of these results is presented by the axial velocity magnitude, mass and head ratio of the ejector at the above cases. Results show that higher pressure ratio and mass ratio (high performance) occur when the nozzle to throat diameter ratio (DN/DT) was (5/8) and (1/8) respectively. Also mass ratio is decreased at all initial pressure when the diameter ratio increased.
Gas flow measurements are pivotal in several medical applications. For instance, mechanical ventilators and respiratory monitoring applications need flowmeters with strict requirements. This study is concerned with a three-dimensional computational fluid dynamics (CFD) analysis. The CFD methodology was confirmed by analyzing the flow characteristics of flexible membrane with trapezoidal orifice plates. Variable area orifice meters (VAOMs) are increasingly being embraced in respiratory monitoring applications, employed in the context of mechanical ventilation within medical settings. Each system integrates a flexible orifice plate within the conduit. The simulations are conducted considering realistic deformations in structure through two-way fluid-structure interactions (FSI) using the Arbitrary-Lagrangian-Eulerian (ALE) approach. This research paper analyzes using the finite volume method (FVM). A thorough numerical simulation was performed for the turbulence models. The orifice's thickness and shape significantly influence pressure drop and deflection.
This work uses different shapes of intake manifold for study the effect on a single cylinder four stroke gasoline engine. A numerical simulation of the flow achieved through five intake manifold designs, using 3D Computational Fluid Dynamic (CFD) software package FLUINT (6.3.). Accordingly, the three-dimensional resolution of Navier-Stokes equations in conjunction with the standard k-ε turbulence model is undertaken to provide knowledge of the air movement nature and examining the intake manifold optimal geometry. Five cases of intake manifold are examined experimentally in order to produce a comprehensive and realistic data set. These data are in the form of engine performance, exhaust gas products and relative AFR for each case separately under different engine speeds. Exhaust gas analyzer type (Infragas-209) is used in the present work to measure exhaust gas concentrations and relative air/fuel ratio ( ). The results were obtained in this investigation showed that a Simulate numerically and experimentally is capable to select the optimized intake system geometry with reliability. Velocity is highest near the outer wall at increased the curvature ratio and pressure is highest near the inner wall at increased the curvature ratio. The secondary flow increases when the engine speeds and curvature ratio increase because of increasing the pressure difference between the inner wall and the outer wall. The effect of these parameters explained on the swirl air movement and tumble inside the cylinder are increasing by increase the engine speed and γ respectively. The increasing in the engine speed and the optimum selection of the manifold which designed enhanced the mixing of the fuel with air. The results showed that the optimized manifold 135º- NE (case 5) due to enhance AFR, fuel consumption and exhaust emissions are improved.
The efficiency of an airfoil can be improved by adjusting its surface. CFD software was used to investigate a 2D airfoil with and without a spanwise semicircular groove on the upper surface. NACA0012 airfoils with and without grooves were analyzed using the k-ω turbulence model. The lift and drag coefficients were used to compared. To investigate the effect of groove location on airfoil efficiency, a groove was added in various locations and compared to a smooth airfoil. The flow velocity remained constant at 20 m/s at all angles of attack (AOA). According to this study, which used ANSYS software to simulate it numerically, the presence of a semicircular groove affects the aerodynamics of the airfoil, resulting in an improved efficiency coefficient of lift, which has risen by 2.25 percent, while the drag coefficient has decreased by 4.32 percent.
The solar chimney power plant is one of the modern models studied on the world. This study presents an engineering and numerical analysis of solar chimney with different parameters. Also, it studies the comparison of two collector base shapes(circular and hexagonal) depend on the five storage material types and their effects on the heat transfer, velocity, efficiency, etc. inside the solar chimney system by considering the solar array intensity equations and the energy equation to calculate the heat transferred and stored by applying the laws of CFD. The finite volume method is used to analyze the geometry physical model by applying a commercial Fluent 6.3 code with Gambit 2.3. The obtained results show that the efficiency of solar chimney is increased by increasing the area of solar glassed collector with circular base shape than the others of polygonal or rectangular one because the circular was covered large area of system. So, the circular ground collector shape for thermal storage is the favour because it is the better to increase the velocity of entering air and to increase the efficiency of turbine. In addition to that the black Pebble storage plate is the better material for heat storage which is convected to air passed for operation of turbine than the other types aluminum, tar, copper and steel seriously.
Solar chimney (SC) together with earth to air heat exchanger (EAHE) is being employed as a low-energy consuming technique to remove undesirable interior heat from a building in the hot seasons. A numerical program "FLUENT 6.3 code" of an earth to air heat exchanger (EAHE) is studied for predicting the outlet air temperature and cooling potential of these devices in Basrah climate. Theoretical analyses have been conducted in order to investigate the ventilation in a solar chimney. The investigation into the viability of Low Energy Earth Pipe Cooling Technology in providing thermal comfort in Basrah. The demand for air-conditioning in buildings in Basrah affects the country escalating energy consumption. Therefore, this investigation was intended to seek for an alternative passive cooling to air-conditioning. The passive technology, where the ground was used as a heat sink to produce cooler air, has not been investigated systematically in hot and humid countries. A sub-soil temperature model adapted for the specific conditions in Basrah is presented and its output compared with CFD modeling. The results have shown that the potential of Earth Pipe is providing lower output temperature of air inlet to the room. We found that the resulting temperature at the buried pipe outlet decreases with increasing pipe length, decreasing pipe diameter, decreasing mass flow rate of flowing air in the pipe and increasing depths up to 4m.
A numerical study of mixed convection inside a horizontal channel with an open square cavity that includes an adiabatic rotating cylinder. The bottom wall of the cavity is heated at a constant temperature, and the remaining walls are adiabatic. The flow is incompressible, laminar and steady state. The equations of continuity, momentum and energy are solved numerically using computational fluid dynamics (CFD) with the commercial software package FLUENT 2019 R1. Reynolds number values of 50, 100 and 150, the Richardson number (0.1 ≤ Ri ≤ 10) and the angular velocity ( ω ) of cylinder is (0.5 ≤ ω ≤ 4) rad/sec with direction counter clockwise. Prandtl number for air flow is ( Pr = 0.7). The results are presented in terms of streamlines, isotherms, and the average Nusselt value is given over the heated bottom cavity. The combined effects of natural and forced convection in and out of the cavity were obtained. The results showed that at low Richardson values, Ri = 0.1 the effect of buoyancy force is neglected. The effect of increasing the cylinder speed is clearly noticeable at low Reynolds values, Re = 50. Average Nusselt values increase with increasing rotational speed of the cylinder for all Richardson values.
This paper demonstrates experimental and numerical studies to investigate in perforation pipes with a phasing 180° and perforation densities 9 spm in a horizontal wellbore. The experimental study was conducted to investigate the phasing angle 180° in a horizontal wellbore. The wellbore has an inner diameter of 44 mm, as well as the length of the pipe is 2 m. For this purpose, a simulation model was created in the wellbore using the ANSYS FLUENT simulation software by using the standard k - e model and applied to the (CFD) with changing the axial flow from (40 - 160) lit/min and constant inflow through perforations from range (20 - 80) lit/min. Concerning the findings of this study, it was noticed that the total pressure drop (friction, acceleration, mixing) goes high as the total flow rate ratio increases. As well as, an increase of the inflow concerning the main flow rate ratio leads to an increase in the total pressure drop and a decrease in the productivity index. Furthermore, the percentage error of the total pressure drop between the numerical and experimental results in test 4 is about 5.4 %. Also, the average velocity goes high with increasing the total flow rates and the velocity keeps increasing along the length of the pipe until it reaches its maximum value at the end of the pipe due to the effect of the perforations. It was concluded that there are the numerical and experimental results reflected a good agreement concerning the study of the flow-through perforations at 180° angle in terms of pressure drop and apparent friction factor, etc.
The electronic equipment industry has developed rapidly in recent years. The amount of heat emitted from such equipment is seriously increased. Increasing the temperature of the electronic devices degrades their performance and as a final result their failure. Therefore, the requirements for an effective cooling system have become more important than ever. One of the most important methods of heat dissipation that the researchers focused on is the use of piezoelectric fans (PE). The current study reviews most of the developments that have taken place since its discovery nearly 40 years ago and focused on reducing power consumption. Most of the improvements and developments have been focused on obtaining optimal designs for these piezoelectric fans, which are used in different applications. This review clarifies the foundations and concepts of designing piezoelectric fans by comparing the data presented in previous studies. Furthermore, in the last ten years, numerical simulation has entered as an effective tool in predicting the optimal design of piezoelectric fans. The design of piezoelectric fans is in two forms, either single or multiple. The single fan system is used within a limited range of applications, as large cooling systems cannot be replaced by it. Therefore, the cooling system consisting of multiple piezoelectric fans is promising as a unique solution to effectively dissipate heat in electronic devices. The percentage of experimental studies is about 32 % while the studies of CFD is about 21 %, and the combined one is about 47 %.
In this study a two dimensional, steady state propagation of the laminar premixed flame was numerically and experimental are investigated. The energy, momentum, continuity equations for species and global reaction mechanism with equation of stat for ideal gases were solved. Constant temperature boundary condition is applied on axi – symmetric in y – direction domain. The governing equations were discretized by using computation fluid dynamics (CFD) and finite-volume method - central differencing scheme, then solved using Gauss-Seidel Iteration method on uniformed grid with VISUAL BASIC code. Effects of equivalence ratio and initial temperature of fresh gases (air – fuel mixture) were investigated for three types of fuel Methane, Propane and Butane. Also the flame speed and flame temperature were experimentally measured for air – fuel (Methane, Propane, Butane and LPG) mixtures. The burning velocity was calculated depending on the flame speed and flame temperature measuring. The flame speed and flame temperature were measured by using optical technique. Effects of equivalence ratio and initial temperature of fresh gases (air – fuel mixtures) on flame speed and flame temperature are investigated experimentally. Results were generated for the detailed description of the local fluid flow and heat transfer characteristics including temperature, axial velocity, density and mole fractions profiles. For example the flame speed reached 274.4 cm/s as a maximum value at Ø=1.1 for propane air mixture, and flame temperature comparison give a good agreement between theoretical and experimental results at rich mixtyre
Mixed convection heat transfer of air in a horizontal channel with an open square cavity is studied numerically. At the center of the cavity, it is an insulated rotating circular cylinder for enhancing the efficiency of heat transmission, the location of the inner cylinder is changed vertically along the centerline of the cavity. Heat is applied to the bottom wall of the cavity at a constant temperature, and the other walls are adiabatic. The flow is steady-state, laminar, and incompressible. Using computational fluid dynamics (CFD) and the commercial software program FLUENT 2019 R1, the equations of continuity, momentum, and energy are numerically solved. The angular velocity of the cylinder range is (0 . 5 ≤ ω ≤ 4) rad/sec in a counterclockwise direction, the Richardson number range ( Ri = 0 . 1 , 1 , 10), Reynolds number is 100 and the cylinder location is ( C = 70 , 50 , 30) mm. The airflow Prandtl number is taken as ( Pr = 0 . 7). The effect of various positions of the rotating cylinder has been examined through the visualization of streamline and isotherm contour, as well as the distribution of the average Nusselt number of the heated surface. The results indicate that the flow field and temperature distributions inside the cavity are strongly dependent on the rotating circular cylinder and the position of the inner cylinder.
The studying of fluid flow throughout fracture in the reservoir is one of the most vital subjects attracted much attention from engineers and geologists. In the present paper, the Dual Porosity-Dual Permeability (DPDP) model has been applied to represent the fluid flow within the fractured reservoirs. This work aimed to demonstrate the utility of the fractures in the petroleum reservoir and how could be used the positive effect of these fractures on the productivity as well. The productivity of single-phase fluid flow within the single horizontal fracture, multi horizontal fractures, and inclined fracture with different orientations (20 o , 30 o , 45 o , and 70 o ) have been implemented by using ANSYS- CFX program and compared with the productivity of conventional (without fractures) reservoirs. In addition to, visualize the velocity streamlines within fracture and matrix zones for the DPDP model. To verify this work the comparison has been made with published paper, which studies the fluid flow through fractures, and a good agreement has been obtained with each other. The study indicates that the presence of macro scale fractures in petroleum reservoirs contributes to increasing the total productivity of these reservoirs. Clearly, the productivity index of multi-horizontal fractures domain is more than twice of nonfractured domain. It is also clear that, when comparing the fractured and nonfractured reservoir, the improvement percentage of the productivity index reaches to (71.8) for a single horizontal fracture with 9 ft length. While this percentage would be about (116.88) if the fracture is inclined with 20 o .
This paper presented experimental and numerical studies to investigate pressure drop in perforation horizontal wellbore with a 90° phasing and 20 spm perforation density. The experimental apparatus has been constructed to calculate the static pressure drop and calculate the exit velocity in the horizontal pipe after mixing the axial flow with the radial flow through the perforations in the wellbore. The specifications of the wellbore used were the inner diameter is 44 mm, length is 2 m, and perforation diameter is 4 mm. For this objective, a simulation model was created in the wellbore using the ANSYS Fluent simulation software by using the standard k-ε model and applied to the (CFD) by changing the axial flow from (40-160) lit/min and constant inflow through perforations from range (0 - 80) lit/min. According to the study's findings, the increase in the radial flow through the perforations increases the total flow rate ratio and the total pressure drop and vice versa. In addition, an increase in the axial flow mixed with radial flow increases the total pressure drop, friction factor, and a decrease in productivity index. Furthermore, the percentage error of the total pressure drop between the numerical and experimental results in test 4 is about 3.83 %. It was found that the numerical and experimental results represented a good agreement about the study of the flow-through perforations at 90° angle in terms of pressure drop and productivity index, etc.
Van Kármán vortex street is considered an important phenomenon that accompanies fluid flow, especially when exposed to a certain barrier, as periodic vortexes occur on both sides of the body that rotate in two opposite directions. This phenomenon occurs in the atmosphere around mountains, oceans, seas, and islands. Also, this phenomenon makes it possible to induce a fluid flow around a specific body present in the flow path. In this study, a model for fluid flow around a cylinder of a certain diameter was taken, where the flow near the boundary layers of the cylinder surface moves slower than near the free stream. In addition, the pressure distribution was studied, and it was observed that there is a pressure gradient due to the difference in momentum at the surface of the cylinder in distant areas due to friction. The study area was divided into fine meshes with Fluent software, especially in the irregular areas. The simulation was implemented for Reynolds numbers Re = 100 and Re = 1500 for incompressible flows. Consequently, the equations that do not depend on pressure are difficult to solve. Therefore, methods linking pressure and velocity were adopted, where the pressure-velocity coupling simple method was used. The first-order forward difference scheme was adopted in representing the differential equations as a function of time when performing the simulation. From the steady state and upwards to Reynolds number Re = 100, it was observed that a twain of vortices appeared on the body at a certain speed range. When the state was changed from the stable state to the transitional state, the results changed, as the flow became asymmetric and unsteady due to vortex shedding phenomena, which led to the generation of vortexes in different ways. The U-Velocity curve was studied for two different cases, and the results showed a large discrepancy between the first order and the second order, where the second order had better behavior but required great effort to reach accurate results. Also, pressure-velocity was studied to satisfy mass conservation, and numerical techniques were used to c ompute the equations of Navier-Stokes in CFD, such as SIMPLEC, PISO, and SIMPLE. An acceptable convergence was not reached with the PISO; therefore, the SIMPLE method was adopted. The pressure gradient was drawn around the cylinder, where it was observed that the pressure was greatest at the front of the cylinder and its lowest value at the end.