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Effects of Inlet and Outlet Ports of Ventilated Square Cavity on Flow and Heat Transfer 通风方腔进、出口对流动和传热的影响
Pub Date : 2020-03-01 DOI: 10.4028/www.scientific.net/DF.26.78
H. Laidoudi, M. Helmaoui, Belbachir Azeddine, Adel Ayad, A. Ghenaim
This paper deals with numerical simulations of forced convection from a pair of identical cylinders arranged in tandem manner inside a square cavity of single inlet and outlet ports. The gap distance between the cylinders is fixed with half of square length. The main purpose of this study is to see the effect of inlet and outlet port positions on fluid flow and heat transfer rate. The governing equations of continuity, momentum and energy have been solved using finite-volume method in laminar, steady and two dimensional directions. The work has been done in the range of these conditions: Re = 1 to 40, at fixed Pr = 7.01. Three positions of inlet and outlet port have been selected. The mean results of flow patterns and distribution temperature are illustrated under the contours of streamline and isotherm respectively. The drag and lift coefficients of each cylinder is computed and discussed. The average Nusselt number of both cylinders is also presented and discussed. It was found that the inlet and outlet ports have significant effects on heat transfer from the confined cylinders.
本文研究了在单进、出口方腔内,一对相同圆柱串联排列的强迫对流的数值模拟。气缸之间的间隙距离固定为平方长度的一半。本研究的主要目的是观察进出口位置对流体流动和换热率的影响。用有限体积法分别在层流、稳态和二维方向上求解了连续、动量和能量的控制方程。工作在以下条件下进行:Re = 1至40,固定Pr = 7.01。选择了三个进出水口位置。分别给出了流线和等温线等高线下流型和分布温度的平均结果。计算并讨论了各气缸的阻力系数和升力系数。给出并讨论了两个圆柱体的平均努塞尔数。研究发现,进气口和出气口对密闭气缸的换热有重要影响。
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引用次数: 5
Computational Analyses of Flow and Heat Transfer at 60° Position of 180° Curved Duct of Square Cross-Section 180°方截面弯曲风管60°位置流动传热计算分析
Pub Date : 2020-03-01 DOI: 10.4028/www.scientific.net/DF.26.53
Mourad Mokeddem, H. Laidoudi, M. Bouzit
3D computational analyses are achieved to predict seriously the influences of thermal buoyancy strength and Dean number on Dean vortices, flow behavior and the rate heat transfer through 180° curved channel of square cross-sectional form. The work shows many results, so this paper emphasizes only on the results of 60° cross-sectional position of the bend duct. The principal partial equations of continuity, momentum and energy are considering in three dimensions under the following assumptions: flow is incompressible and laminar, and it is solved in steady-state. The aforementioned equations are subjected to suitable boundary conditions under following range as: Dean number of De = 125 to 150, Richardson number of Ri = 0 to 2 at fixed value of Prandtl number Pr = 1. The principal results of this work are illustrated as streamline and isotherm contours to draw to flow patterns and temperature distributions respectively. The axial velocity profile is shown versus above conditions, the local Nusselt number is also presented along the wall of 60° cross-sectional position. The results show that the thermal buoyancy can balance the effect of centrifugal force of fluid particles at the angular position of 60°.
通过三维计算分析,较好地预测了热浮力强度和迪安数对迪安涡、流动特性和180°方形截面弯曲通道换热速率的影响。由于工作结果较多,本文只着重讨论弯管60°截面位置的结果。连续性、动量和能量的主偏方程是在三维空间中考虑的,假设流动是不可压缩的和层流的,并在稳态下求解。上述方程在下述范围内具有合适的边界条件:在Prandtl数Pr = 1的定值下,De的Dean数为125 ~ 150,Ri的Richardson数为0 ~ 2。本工作的主要结果分别用流线和等温等温线来表示流动模式和温度分布。给出了在上述条件下的轴向速度分布,并给出了沿壁面60°横截面位置的局部努塞尔数。结果表明,热浮力可以平衡60°角处流体颗粒离心力的影响。
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引用次数: 1
MHD Heat Transfer Flow of Casson Fluid with Velocity and Thermal Slips over a Stretching Wedge in the Presence of Thermal Radiation 热辐射存在下带速度和热滑移的卡森流体在伸展楔上的MHD换热流
Pub Date : 2020-03-01 DOI: 10.4028/www.scientific.net/DF.26.1
N. Bano, B.B. Singh, S. Sayyed
This article investigates the boundary layer flow and heat transfer of an electrically conducting Casson fluid over a stretching wedge by considering the effects of suction/injection, velocity and thermal slips and thermal radiation. By applying the appropriate similarity transformations,the governing partial differential equations are transformed to highly non-linear ordinary differential equations. These resulting similarity equations are then solved by a new analytic method namely DTM-BF, based on differential transformation method (DTM) and base function (BF). A comparativestudy of the present numerical results has been made with the already published results available in the literature. The effects of various governing parameters on the flow and heat transfer characteristics have been discussed graphically.
考虑吸/注、速度、热滑移和热辐射的影响,研究了导电卡森流体在拉伸楔上的边界层流动和传热。通过适当的相似变换,将控制偏微分方程转化为高度非线性的常微分方程。基于微分变换法(DTM)和基函数法(BF),提出了一种新的解析方法——DTM-BF。将目前的数值结果与文献中已经发表的结果进行了比较研究。讨论了各种控制参数对流动和换热特性的影响。
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引用次数: 5
Effects of Retardation Time on Non-Newtonian Electro-Osmotic Flow in a Micro-Channel 延迟时间对微通道中非牛顿电渗透流动的影响
Pub Date : 2020-03-01 DOI: 10.4028/www.scientific.net/DF.26.39
G. Adamu, A. M. Kwami, M. Abdulhameed, D. G. Yakubu
In this paper, we have studied the effects of retardation time of non-Newtonian Oldroyd-B type fluid driven by Helmholtz-Smoluchowski velocity in a micro-channel. The potential electric field is applied along the length of the micro-channel describing by the Poisson–Boltzmann equation. The governing model equation was solved analytically using the classical method of partial differential equations. Analytical solution was simulated with the help of MATHEMATICA software and the graphical results for various physical flow parameters were analyzed. Results shows that for larger values of retardation time of a viscoelastic fluid the higher the viscoelastic effect of the fluid and this makes it to need more time for the stress to respond to deformation. Also, the electrokinetic width of micro-channel play a vital rule on the performance of velocity distribution.
本文研究了在Helmholtz-Smoluchowski速度驱动下,非牛顿Oldroyd-B型流体在微通道中滞流时间的影响。用泊松-玻尔兹曼方程描述沿微通道长度方向施加势电场。采用经典的偏微分方程方法对控制模型方程进行解析求解。利用MATHEMATICA软件对解析解进行了仿真,并对各物理流动参数的图形化结果进行了分析。结果表明,粘弹性流体滞延时间越大,流体的粘弹性效应越强,这使得应力响应变形所需的时间越长。此外,微通道的电动力宽度对速度分布的性能也有重要影响。
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引用次数: 3
Computational Analysis on Gas Turbine Blade by Hole Modified for Optimization the Effectiveness 为优化效率而进行孔修正的燃气轮机叶片计算分析
Pub Date : 2020-03-01 DOI: 10.4028/www.scientific.net/DF.26.157
Farouk Kebir
In order to reduce the operating costs of the engine, turbine designers must also increase the life of their components. However, high gas temperatures throughout the engine require more cooling air or better cooling efficiency to protect the parts from thermal damage. This study presents numerical research on cooling holes. Research focused on aerodynamics and thermal aspects of shallow whole angle. The numerical simulation is performed based on Reynolds Averaged Navier-Stokes (RANS) equations with SST turbulence model by using CFX. A modification has been done in the normal injection hole of 35°, by injecting the cold fluid at different blowing ratio, providing a significant change in the shape of holes which later we found in our numerical investigation giving good quality of film cooling effectiveness.
为了降低发动机的运行成本,涡轮设计师还必须增加其部件的寿命。然而,整个发动机的高温需要更多的冷却空气或更好的冷却效率,以保护部件免受热损伤。本文对冷却孔进行了数值研究。研究主要集中在浅整体角的空气动力学和热学方面。利用CFX软件,基于SST湍流模型的Reynolds平均Navier-Stokes (RANS)方程进行了数值模拟。通过以不同的吹气比注入冷流体,对35°的正常注射孔进行了改进,使孔的形状发生了明显的变化,后来我们在数值研究中发现,这种变化使膜冷却效果得到了很好的改善。
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引用次数: 1
Convective Heat Transfer Analysis of Hydromagnetic Micropolar Fluid Flow Past an Inclined Nonlinear Stretching Sheet with Variable Thermo-Physical Properties 磁微极流体流过具有可变热物性的倾斜非线性拉伸片的对流换热分析
Pub Date : 2020-03-01 DOI: 10.4028/www.scientific.net/DF.26.63
E. Fatunmbi, S. Okoya, O. Makinde
The current work examines mixed convection boundary layer flow and heat transfer attributes in hydromagnetic micropolar fluid past a heated inclined sheet which stretches nonlinearly along the direction of flow. The impact of variable thermo-physical characteristics of the fluid together with the influence of magnetic field, thermal radiation and viscous dissipation are also checked on the flow field. The modelled governing equations are translated from partial to ordinary differential equations via relevant similarity transformations and the resulting equations are subsequently solved numerically by means of shooting techniques in company with Runge-Kutta integration algorithms. The reactions of the skin friction coefficient, Nusselt number, dimensionless velocity as well as temperature to variations in the emerging controlling parameters are illustrated through different graphs. In the limiting situations, the results obtained exhibit a strong relationship with the existing related works in literature. The facts emanated from this study also reveal that the thickness of the thermal boundary layer grows widely with a rise in the Eckert number and Biot number parameters whereas increasing the material (micropolar) and thermal conductivity parameters have opposite effects on the rate of heat transfer.
本文研究了磁微极流体经过沿流动方向非线性拉伸的加热倾斜薄片时的混合对流边界层流动和传热特性。考察了流体热物理特性的变化以及磁场、热辐射和粘性耗散对流场的影响。通过相似变换将所建立的控制方程由偏微分方程转化为常微分方程,并结合龙格-库塔积分算法对所得到的方程进行数值求解。通过不同的图形说明了表面摩擦系数、努塞尔数、无量纲速度和温度对新出现的控制参数变化的反应。在有限的情况下,所得结果与文献中已有的相关作品表现出很强的关联性。研究结果还表明,随着埃克特数和比奥数参数的增加,热边界层的厚度也会大幅增加,而增加材料(微极性)和导热系数参数对换热速率的影响则相反。
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引用次数: 13
MHD Stagnation-Point Flow and Heat Transfer over an Exponentially Stretching/Shrinking Vertical Permeable Cylinder MHD滞点流动和传热在指数拉伸/收缩垂直可渗透圆柱体
Pub Date : 2020-03-01 DOI: 10.4028/www.scientific.net/DF.26.23
N. Bano, B.B. Singh, S. Sayyed
The present literature analyzes the MHD stagnation-point flow of an incompressible fluidover an exponentially stretching/shrinking permeable cylinder in the presence of a transverse magnetic field, and suction/injection. The governing partial differential equations in cylindrical form aretransformed into coupled ordinary differential equations (ODEs) using suitable similarity transformations. These ODEs are solved using optimal homotopy analysis method (OHAM) via Mathematicasoftware BVPh 2.0 package. The effects of various governing parameters such as curvature parameter, magnetic parameter, wall transpiration parameter, velocity ratio parameter and Prandtl number onvelocity and temperature profiles have also been examined graphically.
本文分析了不可压缩流体在横向磁场和吸力/注入作用下在指数拉伸/收缩渗透性圆柱体上的MHD滞点流动。采用适当的相似变换,将圆柱形式的控制偏微分方程转化为耦合的常微分方程。利用数学软件bvph2.0包,采用最优同伦分析法(OHAM)求解这些ode。本文还考察了曲率参数、磁参数、壁蒸腾参数、速比参数和普朗特数等控制参数对速度和温度分布的影响。
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引用次数: 0
Finite Difference Investigation of a Polluted Non-Isothermal Variable-Viscosity Porous Media Flow 污染非等温变黏度多孔介质流动的有限差分研究
Pub Date : 2020-03-01 DOI: 10.4028/www.scientific.net/DF.26.145
C. Nwaigwe, O. Makinde
We extend previous studies of channel flows to porous media flows with combined effects ofboth heat and mass transfer. We consider a temperaturedependent viscosity fluid and a concentrationdependent diffusivity in an unsteady and pressuredriven nonisothermal Brinkman flow. This leads to the governing equations for velocity, concentration and temperature. By lagging nonlinear coefficients, in time, a convergent finite difference scheme is formulated. We adopt the method of manufactured solutions to verify the convergence and second order spatial accuracy of the scheme. The impact of the flow parameters on the flow fields are numerically investigated. The results show that increase in the Darcy number and temperature parameter both increase the velocity while the increase in the pollutant diffusion parameter decreases the pollutant concentration.
我们将先前的通道流动研究扩展到具有传热传质联合效应的多孔介质流动。我们考虑在非定常和压力驱动的非等温Brinkman流中温度依赖的粘度流体和浓度依赖的扩散系数。这就引出了速度、浓度和温度的控制方程。通过滞后非线性系数,在时间上得到收敛的有限差分格式。采用制造解的方法验证了该方案的收敛性和二阶空间精度。数值研究了流动参数对流场的影响。结果表明,达西数和温度参数的增大均使流速增大,而污染物扩散参数的增大则使污染物浓度减小。
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引用次数: 2
A Study of Fractional Relaxation Time Derivative on Blood Flow in Arteries with Magnetic and Thermal Radiation Effects 磁热辐射作用下动脉血流的分数阶松弛时间导数研究
Pub Date : 2020-03-01 DOI: 10.4028/www.scientific.net/DF.26.126
D. G. Yakubu, M. Abdulhameed, G. Adamu, A. M. Kwami
In this paper, a fractional relaxation model is studied to determine the effect of heat transfer and magnetic field on the blood flow. The flow is due to an oscillating periodic pressure gradient and body acceleration. We apply Laplace transform as well as finite Hankel transform to obtain the closed form solutions of the velocity and temperature distributions of the fractional time partial differential equations. Effect of the fluid flow parameters are shown graphically with changes in the ordinary model as well as the fractional parameters. The analysis shows that the fractional derivative is an excellent tool which gives remarkable change in controlling temperature and blood flow. The analysis depicts graphically, that in the presences of strong applied (exterior) magnetic field, reduces the temperature and blood flow velocities, which is appropriate to avoid tissues damage during treatment. In addition, it is seen that some of the aforementioned parameters influenced the fluid flow profiles in increasing and decreasing fashion which is interpreted as useful to the study.
本文研究了一个分数松弛模型,以确定传热和磁场对血流的影响。流动是由于振荡的周期性压力梯度和体加速度。应用拉普拉斯变换和有限汉克尔变换,得到了分数阶时间偏微分方程的速度分布和温度分布的封闭解。用图形显示了流体流动参数对普通模型和分数参数变化的影响。分析表明,分数阶导数是一种很好的控制温度和血流变化的工具。分析图解地描述了,在强施加(外部)磁场的存在下,降低了温度和血液流动速度,这是适当的,以避免治疗期间组织损伤。此外,我们还看到,上述一些参数对流体流动曲线的影响呈增减趋势,这对研究是有用的。
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引用次数: 3
Forced Convection Heat Transfer from a Pair of Circular Cylinders Confined in Ventilated Enclosure 密闭通风箱内一对圆柱的强制对流换热
Pub Date : 2020-03-01 DOI: 10.4028/www.scientific.net/DF.26.104
M. Helmaoui, H. Laidoudi, Azzedine Belbachir, Adel Ayad, Abedallah Ghaniam
This paper deals with a numerical simulation of laminar forced convection heat transfer from a pair of identical circular cylinders placed at the center of square cavity in the line array, the cavity is ventilated with single inlet and outlet ports, the inlet port is located at the middle of left vertical wall and the outlet port is located at the middle of right vertical wall. The work represents the effects of the distance between cylinders and Reynolds number on fluid flow and heat transfer rate. The governing equations of continuity, momentum and energy are solved by using finite-volume method. The obtained results are represented and discussed for following conditions: Reynolds number Re = 1 to 40, Prandtl number Pr = 7.01 and the gap distance S = 0.3L to 0.7L, where L is the cavity length. The main results are potted under the streamline and isotherm contours, the total drag coefficient and average Nusselt number of each cylinder is plotted versus studied parameters. It is found that the increase in the gap space distance between cylinders increases the heat transfer rate.
本文对线阵方形空腔中心放置一对相同圆柱的层流强制对流换热进行了数值模拟,空腔采用单进、单出口通风,进、出口分别位于左、右垂直壁中间。研究了圆柱间距和雷诺数对流体流动和换热速率的影响。用有限体积法求解了连续、动量和能量的控制方程。在雷诺数Re = 1 ~ 40,普朗特数Pr = 7.01,间隙距离S = 0.3L ~ 0.7L的条件下,对所得结果进行了表示和讨论,其中L为空腔长度。主要结果在流线和等温等高线下进行了保存,并根据研究参数绘制了各柱体的总阻力系数和平均努塞尔数。研究发现,圆柱间间隙距离的增加会增加换热率。
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引用次数: 6
期刊
Diffusion Foundations
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