旋转方形截面螺旋管内流动与传热特性

利用数值计算方法研究了旋转矩形截面螺旋管内的粘性流动，分析了在离心力，科氏力共同作用下曲线管道中的二次流动结构、轴向流速分布、截面温度分布、摩擦系数比以及管道Nusselt数比随各参数的变化情况。计算结果表明：当旋转方向和主流方向相同时，旋转的作用与增大Dean数的作用相同，使得管道摩擦系数变大，管道换热效果增强，而当旋转方向和主流方向相反时，管道内流动结构变化十分明显，当F≈-1．2时(F为科氏力与离心力之比)，二次流出现类似于直扭管内的鞍状流动结构，轴向速度类似于静止直管内的流动结构，管道内的摩擦系数与静止直管内的摩擦系数大约相等，换热效果减至最弱；挠率对流动结构以及摩擦系数比和Nusselt系数比的影响效果与F有关。     

Numerical calculations for two-phase jet flow of a mixture of pulverized-coal and gas

In this paper, Euler-Lagrange type equations are used to describe the jet flow of a mixture of pulverized-coal and gas, which is an unsteady axisymmetric two-phase flow. By means of the finite-difference method, the coal particle's distribution, velocity and trajectory in the flow field are obtained. The coal particles are represented by a finite number of computational particles. Each particle's diameter is randomly assigned according to a given distribution. The states of the computational particles are different from each other. Turbulence is accounted for in a stochastic model. Explicit time-splitting scheme is used to calculate the strongly coupling interphase term. The numerical results are reasonable. The comparison between the numerical results and the experiment data for the case of the oil droplet injection shows good agreement. This numerical technique can be extended to the calculation of other two-phase flows of dilute particles or a droplet system. Mr. Mei Renwei also participated in the work of this paper.     

绕壁面小障碍物的湍流边界层研究

采用RNGK－ε模型，对统平板壁面上的条柱、方柱等多种不同形状二维小障碍物的固壁剪切湍流进行数值研究，获得了小障碍物下游回流区及其发展区的时均速度场、回流分离点长度和湍流边界层厚度，计算结果与实验比较吻合良好．结果表明，小障碍物在壁面上的设置，明显地改变了平板壁面边界层的湍流形态和结构．     

Multifunctional AuI‐based AIEgens: Manipulating Molecular Structures and Boosting Specific Cancer Cell Imaging and Theranostics

Gold(I) N‐heterocyclic carbene (Au^I‐NHC) complexes have emerged as potential anticancer agents owing to their high cytotoxicity and stability. Integration of their above unique functions with customized aggregation‐induced emission (AIE) luminogens to achieve specific bioimaging and efficient theranostics to cancer is highly desirable but is rarely studied. Now, a series of novel Au^I‐NHC compounds were developed with AIE characteristics. A complex with a PPh₃ ligand was selected out as it could achieve both prominent specific imaging of various cancer cells and efficient inhibition of their growth with negligible toxic effects on normal cells due to the targeting binding and strong inhibition towards thioredoxin reductase. This complex could also act as a powerful radiosensitizer to boost the anticancer efficacy with performance superior to that of popularly used auranofin. It holds great potential as a specific and effective theranostic drug in cancer diagnosis and precise therapy.     

环形截面螺旋管道内的粘性流动

根据张量分析,建立了非正交的曲线柱坐标系巾的N-S方程,采用摄动法求解环形截面螺旋管道内的粘性流动。结果表明:环形截面上存在二次流     

Fluid flow in a helical pipe

Without simplifying the N-S equations of Germano's^[5], we study the flow in a helical circular pipe employing perturbation method. A third perturbation solution is fully presented. The first- second- and third-order effects of curvature κ and torsion τ on the secondary flow and axial velocity are discussed in detail. The first-order effect of curvature is to form two counter-rotating cells of the secondary flow and to push the maximum axial velocity to the outer bend. The two cells are pushed to the outer bend by the pure second-order effect of curvature. The combined higher-order (second-, third-) effects of curvature and torsion, are found to be an enlargement of the lower vortex of the secondary flow at expense of the upper one and a clockwise shift of the centers of the secondary vortices and the location of maximum axial velocity. When the axial pressure gradient is small enough or the torsion is sufficiently larger than the curvature, the location of the maximal axial velocity is near the inner bend. The equation of the volume flux is obtained from integrating the perturbation solutions of axial velocity. From the equation the validity range of the perturbation solutions in this paper can be obtained and the conclusion that the three terms of torsion have no effect on the volume flux can easily be drawn. When the axial pressure gradient is less than 22.67, the volume flux in a helical pipe is larger than that in a straight pipe.     

Stokes flow of a rotating sphere around the axis of a circular orifice or a circular disk

This paper presents an infinite series solution to the creeping flow equations for the axisymmetric motion of a sphere of arbitrary size rotating in a quiescent fluid around the axis of a circular orifice or a circular disk whose diameters are either larger or smaller than that of the sphere. Numerical tests of the convergence are passed and the comparison with the exact solution and other computational results shows an agreement to five significant figures for the torque coefficients in both cases. The torque coefficients are obtained for the sphere located up to a position tangent to the wall plane containing either the orifice or the disk. It is concluded that the torque coefficients of the sphere and the disk are monotonically increasing with the decrease of the distance from the disk or the orifice plane in both cases.