【作者】 陈红；

【导师】 张红伟； 田溪岩；

【作者基本信息】 东北大学 ， 动力工程（专业学位）， 2020， 硕士

【摘要】 流体边界层流动在科学研究和工程应用等领域是一种常见现象,随着航空工业的迅速发展,流体边界层理论快速发展起来。研究流体边界层内的速度分布和温度分布,有利于研究物体的阻力损失和传热机理,从而设计出节约能源,提高经济效益的流体机械。因此吸引了很多的学者对流体边界层的流动和传热问题进行研究。本文的主要研究内容为以下两部分:第一部分,研究了二维稳态Al2O3-H2O纳米磁流体在垂直可移动渗透平板上的流动。建立了描述纳米磁流体流动和传热的数学模型,运用流函数法将偏微分控制方程组和边界条件进行降维转化为常微分方程组,采用Runge-Kutta法对常微分方程组和Shooting Method处理后的边界条件进行求解(使用MATLAB)。对于纳米颗粒体积分数为0.1的纳米流体,分析讨论了对流换热参数、速度参数、幂律指数和抽吸参数对纳米流体流动边界层速度和温度的影响。发现:幂律指数的增加会导致速度增大,温度随之降低。速度参数增加,温度和壁温下降,而速度增加。抽吸参数增加,温度边界层厚度变薄。对流换热参数增大会使温度边界层厚度也将随之增大。第二部分,研究了二维非稳态牛顿流体在移动可渗透平板上的驻点边界层流动问题,开发了交错网格下的有限差分投影算法(FORTRAN编程)。其中,针对不合理压力场的检测,空间离散采用交错网格有限差分法;针对方程中压力和速度的耦合,采用的是投影算法;针对方程中非线性项,采用Adams-Bashforth格式。最后,分析并讨论了壁面运动参数和传质参数等对驻点流体速度边界层和流体形态的影响。发现:随着传质参数变大,吸力使流动边界层变薄。随着壁面吹力的增大,驻点和分流线一起向上移动,外部区域变薄,吹入一定值后外部区域被吹出。壁面运动参数增大使速度边界层的厚度变薄。更多还原

【Abstract】 Fluid boundary layer flow is a common phenomenon in scientific research and engineering applications.With the rapid development of the aviation industry,fluid boundary layer theory develops rapidly.Studying the velocity distribution and temperature distribution in the fluid boundary layer is conducive to studying the resistance loss and heat transfer mechanism of the object,to design the fluid machinery that can save energy and improve economic benefits.Therefore,it has attracted many scholars to study the flow and heat transfer of the fluid boundary layer.The main research content of this paper is divided into the following two parts:The First part,a two-dimensional steady forced convection boundary layer viscous incompressible flow of alumina-water nanofluid over a moving permeable vertical flat plate under the effect of a magnetic field normal to the plate is studied in this paper.A mathematical model describing the flow and heat transfer of nanometer magnetic fluid is established.The partial differential control equations and boundary conditions are reduced to be the ordinary differential equations by flow function method.The transformed ordinary differential equations and the boundary conditions treated by the Shooting Method are solved numerically using the Runge-Kutta Method(using MATLAB).Numerical results are obtained for various of the convective heat transfer parameter,the velocity parameter,the power law exponent and the suction parameter.The effects of these parameters on the flow and heat transfer characteristics are determined and discussed in detail.For nanofluids with a volume fraction of 0.1,the increasing of the power law exponential will lead to the increasing of the velocity and the decreasing of the temperature.As the suction parameter increasing,the thickness of the temperature boundary layer will become thinner.In addition,as the convective heat transfer parameter increasing,the thickness of the temperature boundary layer will also increase.The second part,the two-dimensional unsteady stagnation-point flow of a Newtonian fluid on a moving permeable plate is studied.A finite-difference projection scheme(FORTRAN programming)based on staggered mesh is developed.For the detection of unreasonable pressure field,the staggered grid finite difference method is used for spatial discretization.The projection scheme is adopted to solve the decoupling of pressure and velocity in the equation.Adams-Bashforth scheme is used to discretely the nonlinear term in the equation.Finally,the influence of wall moving parameter and mass transfer parameter on velocity boundary layer and fluid morphology of stagnation-point fluid is analyzed and discussed.With the increase of mass transfer parameters,the suction thins the flow boundary layer.With the increasing of wall blowing force,the stagnation point and the shunt line move upward together,and the external region will get thin.And the outer area will be blown out when the wall blowing force reaches a certain value.With the increasing of the motion parameter,the thickness of the velocity boundary layer will get thin.更多还原