Purpose

The purpose of this paper is to analyze the unsteady conjugate mixed convective heat transfer characteristics in a vented porous cavity under the combined effects of moving conductive elliptic object and magnetic field.

Design/methodology/approach

The finite element method and arbitrary Lagrangian-Eulerian (ALE), impacts of Reynolds number, Hartmann number, aspect ratio of the conductive ellipse and moving speed of the object on the hydro-thermal performance are analyzed.

Findings

It was observed that the dynamic characteristics of the local and average Nu number of each hot wall are different. Magnetic field strength increment resulted in the enhancement of average Nu number for bot steady and transient case while the optimum case for best hydro-thermal performance is achieved for highest Ha number and non-dimensional time of 10. Higher value of average Nu and lower pressure coefficient are achieved for aspect ratio of 4 and non-dimensional time of 10. When the moving velocity of the conductive ellipse is considered, 42% enhancement in the average Nu is obtained at non-dimensional time of 20 and object velocity equals to 0.012 times entering fluid velocity in the negative y direction while the pressure coefficient is higher. The moving object is used as a useful tool to control the dynamic features of heat transfer in a vented cavity.

Originality/value

The present method of convective heat transfer control inside a vented cavity with a moving elliptic object is novel and can be used as an effective tool with magnetic field effects owing to diverse use of convection in cavities with vented ports in many practical thermal engineering systems.

中文翻译：

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具有通风口的碳纳米管水纳米流体中MHD和移动导电椭圆体联合效应的非定常共轭传热

目的

本文的目的是分析在移动的导电椭圆物体和磁场的共同作用下通风多孔腔内的非定常共轭混合对流传热特性。

设计/方法/方法

分析了有限元法和任意拉格朗日-欧拉法(ALE)、雷诺数、哈特曼数、导电椭圆长宽比和物体移动速度对水热性能的影响。

发现

观察到每个热壁的局部和平均Nu数的动态特性是不同的。磁场强度增加导致机器人稳态和瞬态情况下平均 Nu 数增加，而最高 Ha 数和无量纲时间为 10 时达到最佳水热性能的最佳情况。 平均 Nu 值较高，压力较低长宽比为 4，无量纲时间为 10 时获得系数。当考虑导电椭圆的移动速度时，在无量纲时间为 20 时，平均 Nu 增加了 42%，物体速度等于 0.012 倍在负y 处进入流体速度方向，而压力系数较高。移动物体被用作控制通风腔中热传递动态特征的有用工具。

原创性/价值

具有移动椭圆物体的通风腔内的对流热传递控制的本方法是新颖的，并且由于在许多实际热工程系统中具有通风口的腔中对流的多种用途，因此可以用作具有磁场效应的有效工具。