层内突进传质扩散数学模型及求解

针对窜流型油藏的特点,抽象出物理原型,同时考虑纵向和横向扩散,建立层内突进传质扩散数学模型.应用拉普拉斯变换,求得层内突进传质扩散数学模型的解析解,并得到小段塞情况下的解析解.应用通用有限元分析软件,建立层内突进传质扩散的几何模型,并求得层内突进传质扩散数学模型的数值解.绘制层内突进传质扩散数学模型的浓度分布二维剖面及不同时间步的浓度变化剖面;通过无因次距离和无因次浓度关系及孔隙体积与无因次浓度关系可以看出,贝克莱特(Pe)数越大,峰值浓度越高,见剂时间越晚.通过解析解及数值解结合的方法,可加深对传质扩散本质的理解.     

完全气体一元变截面有传热有摩擦流动的一些不定常解析解

本文给出了可压缩完全气体的一系列－元不定常流动解析特解，而且流动中可以包括有变截面、传热与摩擦等各种变化。这些解除在理论上有其重要意义外，还可以用来作为检验各种数值解的标准解之用。     

吸附制冷用吸附单元管设计和传热传质性能研究

本文介绍了一种具有较好传热传质性能的吸附式制冷用吸附单元管,该吸附单元管直接用烟气加热、空气冷却, 可以用于沸石等高温吸附剂。该吸附单元管在加热／冷却流体侧和吸附剂侧均设了翅片,吸附剂内部的传热尺度不大于 2．5 mm,最大传质尺度不大于11 mm。通过数值计算和由吸附单元管组合而成的吸附床的性能初步试验,证明该结构形式的吸附单元管具有优良的传热传质性能。     

亚临界与超临界压力水在管内的对流传热与传质

本文对含有金属腐蚀物杂质的亚临界与超临界压力水在竖直加热圆管内的受迫对流与混合对流传热与传质进行了数值模拟，分析了变物性、浮升力以及压力等因素对管内对流传热与传质的影响。结果表明：浮升力使自下而上流过竖直加热圆管的对流传热和传质增强；在不同的温度条件下，超临界压力水的热物性对传热传质的影响有很大不同。     

波纹板片上降膜吸收过程的传热传质数值仿真

建立了在连续的竖直波纹板上降膜吸收过程的传热传质数学模型,并进行了无因次化处理和仿真数值计算。给出了溶液液膜内流场、温度场、质量分数分布的计算结果,比较了交叉双尺度波纹板片和当量平板上的吸收传热和传质系数随不同溶液喷淋密度的变化结果,显示出前者具有更好的性能,并讨论了波纹节距对传热和传质系数的影响关系。     

多孔圆肋传热传质分析

多孔肋片传热传质过程在自然界中广泛存在,本文对水在多孔圆肋中流动产生的传热传质现象进行了研究,建立了相应的物理数学模型,通过数值计算获得肋片内水的温度和流量分布,以及水沿肋长方向蒸发率的变化。讨论了外界空气温度对多孔肋片中水的流量和蒸发率的影响,并对孔隙率、长径比等因素对肋片传热传质效率的作用进行了分析．     

料层孔隙率对高炉炉身传热传质过程的影响

为研究料层孔隙率对高炉炉身内部传热与传质过程的影响,分别对料层孔隙率为常数、随化学反应程度变化两种条件下的高炉炉身传热与传质过程进行了数值模拟。料层结构由自编程的料层分布程序计算而得,炉腰下部入口处的气流速度、温度以及组分质量分数等数据取自于回旋区喷煤过程的数值模拟结果。数值模拟结果表明,两种模型下炉身内部压差分布、煤气速度分布、气固两相温度分布、CO和CO_2质量分数分布态势相同,但具体数值存在不同程度的差异,非定常孔隙率模型的预测结果与现场检测结果更为吻合,定常孔隙率模型对炉身压差的预测结果与生产实践数据的相对误差较大,因此采用非定常料层孔隙率有利于提高高炉炉身传热传质过程数值模拟精度.     

内含质量源的超临界压力水的自然对流传热与传质分析

本文对内含质量源的超临界压力水在竖直加热表面上的层流自然对流传热与传质的耦合问题，在第一类边界条件下进行了数值求解，分析讨论了内部质量源以及超临界压力下水的热物性的剧烈变化对传热与传质的影响，并给出了计算用的准则关系式。     

喷淋蒸发翅管式冷凝器传热传质研究

采用蒸发式冷凝器可以降低制冷装置不可逆传热损失,提高机组效率。该文提出在制冷装置中采用喷淋蒸发翅管式冷凝器,分析了喷淋蒸发翅管式冷凝器的传热过程,建立其传热传质数学模型和设计计算方法,简要分析了环境温湿度、管翅结构、风速、淋水量等一些主要因素对传热传质性能的影响,为该种冷凝器的设计和应用提供理论参考。     

矩形封闭腔内非饱和多孔介质的传热传质特性研究

本文建立了矩形封闭腔内非饱和多孔介质的二维传热传质数理模型,并对Ｒ１１３的蒸发相交进行了数值模拟。根据计算结果着重讨论了流体瑞利数Ｒａ,介质达西数Ｄａ以及腔体冷热端温差△Ｔ的变化对其传热传质特性的影响,得出一些有用的可指导工程实践的结论。     

Explicit analytical solutions of the anisotropic Brinkman model for the natural convection in porous media (Ⅱ)

Some algebraically explicit analytical solutions are derived for the anisotropic Brinkman model―an improved Darcy model―describing the natural convection in porous media. Besides their important theoretical meaning (for example, in analyzing the non-Darcy and anisotropic effects on the convection), such analytical solutions can be the benchmark solutions that can promote the development of computational heat and mass transfer. Some solutions considering the anisotropic effect of permeability have been given previously by the authors, and this paper gives solutions including the anisotropic effect of thermal conductivity and the effect of heat sources.     

Explicit analytical solutions of the anisotropic Brinkman model for the natural convection in porous media (II)

Some algebraically explicit analytical solutions are derived for the anisotropic Brinkman model—an improved Darcy model—describing the natural convection in porous media. Besides their important theoretical meaning (for example, in analyzing the non-Darcy and anisotropic effects on the convection), such analytical solutions can be the benchmark solutions that can promote the development of computational heat and mass transfer. Some solutions considering the anisotropic effect of permeability have been given previously by the authors, and this paper gives solutions including the anisotropic effect of thermal conductivity and the effect of heat sources.     

变热物性非定常导热方程的一些显式解析解

各种变热物性（热传导系数、密度与比热为变数）的非定常导热方程的解析解在理论上是有意义的；而且它们对计算传热学也很有实用价值；可以作为标准解来校核各种数值计算以及用来启发发展各种计算技巧例如差分格式、网格生成等等。但已知的解析解很少。本文对直角座标下沿几何座标变热物性的非定常几何一元及二元的导热方程导出了一些代数显式解析解，其中有些解包含有任意函数，其实是无限多个解；可作为发展导热学理论及计算导热学之用．     

Magnetohydrodynamic and radiation effects on the heat transfer of a continuously stretching/shrinking sheet with mass transpiration of the horizontal boundary

The aim of this paper is the investigation of heat transfer regarding the cases of both stretching and shrinking sheets with a sponge-like horizontal wall that allows for mass transpiration. The effects of Prandtl number, radiation and external magnetic field are extensively examined. The Navier-Stokes equations are reduced to partial differential equations, which are eventually become ordinary differential equations and solved analytically. Furthermore, the power-law wall temperature and heat flux boundary conditions are imposed on the boundary layer energy equation for obtaining exact analytical solutions. The results revealed that in both the stretching and shrinking sheet scenarios the thickness of the thermal boundary layer decreases with either increasing of transpiration as well as the Chandrasekhar and Prandtl number numbers or decreasing radiation number. Additionally, the characteristics of the heat transfer regarding a shrinking sheet and those of a stretching sheet are found not to be similar. In fact, a new solution branch appeared which indicates that multiple solutions may emerge under certain circumstances. Finally, by using the present analytical relationships, theoretical guidelines can be given for regulating the procedure.     

非规则形状介质内辐射-导热耦合传热的间断有限元求解

采用间断有限元法(discontinuous finite element method,DFEM)求解非规则形状介质内的辐射导热耦合传热问题,得到了典型非规则形状介质内辐射导热耦合传热问题的高精度数值结果.和传统连续型有限元方法不同,DFEM将计算区域划分成相互独立的离散单元,形函数的构造、未知量的加权近似以及控制方程的求解均在每一个离散单元上进行.通过在单元之间施加迎风格式的数值通量,DFEM保证了整个计算区域的连续性,因此这种方法兼具良好的几何灵活性和局部守恒性.推导了辐射传输方程和能量扩散方程的射导热耦合传热问题,得到了典型非规则形状介质内辐射导热耦合传热的高精度数值结果.     

高超声速可压缩流中粗糙壁热流研究

用计算流体力学（CFD）数值模拟和理论方法对高超声速可压缩湍流中粗糙壁面热增量进行研究. 着重考虑粗糙单元密度和粗糙单元形状对粗糙表面热流的影响. 结果表明： ①粗糙单元密度变化时, CFD数值方法计算所得的粗糙单元等效热流随着粗糙单元密度的降低而增加, 理论方法预测结果的规律随方法不同而不同;②在相同粗糙单元密度和高度时,如果粗糙单元形状改变,CFD计算结果也随之发生改变. 理论预测方法所得结果不发生变化.     

Two analytic methods applied to radiative transfer in the linear-anisotropic scattering medium with graded index and diffuse gray boundaries

The curved ray-tracing method is extended to radiative transfer in the graded index medium with diffuse gray boundary conditions instead of black boundary conditions and the pseudo-source adding method is extended to the case of the linear-anisotropic scattering medium with graded index from non-scattering medium. Furthermore, the equivalence of the two methods is verified by formulation derivation. As exact analytical solutions, both the methods have high accuracy and fast computational speed. The predicted temperature distributions and dimensionless radiative heat flux at radiative equilibrium are determined by the proposed methods, and the numerical results are compared with the data in references. The results show that the present methods have a good accuracy. Influences of various combinations of refractive index and boundary emissivities on the temperature distributions and dimensionless radiative heat flux are also investigated.     

孤立系内热传导过程(火积)耗散的解析解

(火积)耗散与熵增均可以作为传热不可逆性的度量, 当前(火积)理论的反对者认为(火积)是不必要的. 为说明(火积)的必要性, 从有效性的角度进行了论证, 即在描述传热过程不可逆性的变化上, (火积)的严格解析解存在, 而熵的严格解析解难以得到. 本文构建了孤立系内的一维及多维热传导模型, 求解了温度及其梯度的级数型解析解, 将其代入(火积)耗散的求解式, 得到其最初的形式为一多重级数的多重积分, 交换积分与级数计算顺序, 并利用特征函数的正交性, 将(火积)耗散求解式中的积分运算求出, 并使级数的维数降低, 最终将其表示为一稳态项与一瞬态项加和的形式, 其极限与文献中的结果一致. 通过对孤立系内(火积)耗散解析解的求解可以得出: 由于热传导过程熵与(火积)的解析解求解难度不同, 在描述传热过程不可逆性变化上, (火积)更加有效; 对于孤立系内不同维数的热传导问题, 只要温度场解析解存在, (火积)耗散解析解均可以应用特征函数正交性求解得到.     

A study of the heat transfer characteristics of a laser rod in a concentric circular tube

An analytical solution was derived from a two-dimensional heat conduction model with non-uniform boundary conditions for a side-pumped, side-cooled cylindrical laser rod. The convective heat transfer coefficient and the spatially varying fluid temperature were determined from the theoretical solutions or experimental correlations of convective heat transfer in an annular passage with prescribed heat fluxes. The first term of the analytical solution coincides with the result of the one-dimensional model. The other terms indicate that the axial temperature-rise in a laser rod has positive correlations with the axial coolant temperature-rise, the radial Biot number and the length-to-radius ratio of the laser rod. Subsequently, a conjugate numerical simulation that couples up the fluid convection and the solid conduction was performed. Compared with the analytical solution, the conjugate numerical simulation better exhibits the entrance effects of flow and heat transfer; therefore, it may provide more accurate solution in specific cases. PACS 44.10.+i; 44.90.+c