逆向环形分布射流迴流特性的数值计算

数值计算表明,逆向多环形分布射流可造成颗粒能直接进入,并能进行强烈的动量、能量交換的理想的迴流区结构。多环形结构可在大范围內造成所需尺寸的迴流区。逆向射流和主流速度比、环直径、射流直径和孔数、环的结构形式及离燃烧室进口的距离是影响迴流特性的主要参数。     

Steady ground-water flow through layered media

This paper deals with the flow through a layered medium that has alternate sand and clay strata. The solutions of plane, axisymmetric and spatial cases are given. Research results in this paper can be applied to seepage calculations and hydraulic engineering designs in flood areas and reclaimed marsh land.List of Symbols A _n Upward leakage factor of the nth sand stratum - A _n Downward leakage factor of the nth sand stratum - [B] Matrix of eigenvector - B _nm Element of [B] corresponding to the nth sand stratum and the mth eigenvalue - C _m , C _N+m Arbitrary constants belonging to the terms contained the mth eigenvalue - C_mj Arbitrary constant belonging to the term contained the mth eigenvalue due to a line source in the jth sand stratum - [D] Inverse matrix of [B] - d _f0 ^sup+ Additional length of the seepage path for ditches in symmetric flow - F, ^F _m Area and dimensionless area corresponding to the mth eigenvalue ( ^F _m = _fm ^sup2 F) - f ₀ Coefficient of additional resistance of partially penetrating well - H Total water head; upstream water head - h, h _n Water head and water head of the nth sand stratum - h _nj Water head of the nth sand stratum due to a line source in the jth sand stratum - h ₀ Surface water head - h/H × 100% Potential - i, j Number - k, k Permeability coefficient of the sand stratum and clay stratum, respectively - k _n , k _n Permeability coefficient of the nth sand stratum and the nth clay stratum, respectively - L Length - m Number - N Total number of sand or clay strata - n Number - Q _j Discharge of a line source distributed along a vertical line in the jth sand stratum - Q _ji The partial discharge of the ith well (or line source), which flows through the screen pipe penetrating the jth sand stratum - qj Discharge of a face source distributed on an area - unit breadth multiplied by the thickness of the jth sand stratum. The abbreviation is: unit discharge of a face source in the jth sand stratum - qji Unit discharge of a face source on the ith surface element in the jth sand stratum - R Constant radius - S Distance; length of a curve - ^S _m Dimensionless length of a curve corresponding to the mth eigenvalue ( ^S _m = _m S) - s Number - T _n , T _n Thickness of the nth sand stratum and the nth clay stratum, respectively - t Number; thickness - x, y, z Cartesian coordinates - y Polar coordinate; radius; distance - ^y _m Dimensionless distance corresponding to the mth eigenvalue ( ^y _m = _m y) - y ₀ Radius of well - y ₀ Radius of equivalent completely penetrating well - Infinitesimal half breadth - Infinitesimal area - Angle - Eigenvalue     

管流系统的可控扰动装置及其应用

阐述了具有可控人工扰动装置的低背景湍动液体管流系统的研制和评价要点在及在高分子减阻液研究中的应用，并指出了这种实验系统在液体内流研究中的重要意义。     

Mathematical programming analysis of bilinear rheological lubrication mechanics

Bilinear rheological lubrication mechanics provides an important basis for the designs of recently developed electrorheological (ER) “smart”journal bearings and those lubricated by mixed fluid-solid lubricants. But there is not yet a reliable and efficient numerical method for such a problem of non-Newtonian fluid mechanics. In the present paper, a finite element method (FEM) together with mat hematical programming solution is successfully used to solve such a problem. A reliable and generalized numerical method for the designs of electrorheological “smart” journal bearings and the bearings lubricated by mixed fluid-solid lubricant is presented.     

大型转子—基础—土壤系统的动力分析

本文对大型汽轮发电机组-基础-土壤系统采用模态综合技术进行了动力分析.用弹性半空间理论建立土壤的模型,基础底板则通过弹性薄板的李兹(Ritz)函数近似解的形式来描述.用三维梁单元来建立基础底板以上的框架结构和转子系统的运动方程.此外,还用模态应变能的相对大小,在这种复杂机械结构系统存在的众多固有频率中,区分出哪些是属于主要为转子系统的固有频率,称为“重要振动固有频率”,以确定系统的临界转速.最后,对引进的一台500MW汽轮发电机组的动力特性进行了分析.     

大理岩非分叉断裂的随机分形模型

本文建立了大理岩沿晶、穿晶及沿晶穿晶偶合断裂的随机分形模型，该模型能与大理岩的整体晶态结构自洽，且模型的分维值与测量值有很好的吻合。     

Effective elastic moduli of an inhomogeneous medium with cracks

In the present paper, the effective elastic moduli of an inhomogeneous medium with cracks are derived and obtained by taking into account its microstructural properties which involve the shape, size and distribution of cracks and the interaction between cracks. Numerical results for the periodic microstructure of different dimensions are presented. From the results obtained, it can be found that the distribution of cracks has a significant effect on the effective elastic moduli of the material. The project supported by the National Education Committee for Doctor     

Analysis of temperature and stress field in Al alloy’s twin wire welding

By analyzing the shape of twin wire welding’s arcs and the track of droplets’ transition, the phenomenon that the twin wire welding’s fore arc and rear arc all deflect to the middle of the two arcs is found. Based on this the double ellipsoid heat source model is amended, and a heat source model which can apply to calculate the twin wire welding’s temperature field is put forward. This model is testified by actual experiment of temperature sampling. By comparing the temperature field of twin wire welding and single wire welding, the results show that twin wire welding has slender weld pool the end part of which is ellipsoid, and its HAZ is narrower than that of single wire welding. So, twin wire welding can not only reduce the Al alloy generating hot crack, but can also weaken the “overaging” softened phenomenon of heat treated strengthening Al alloy. In the end, the evolving rules of 2219 Al alloy’s longitudinal and transverse stress when welded with twin wire welding are analyzed.     

Validating a GIS-based multi-criteria method for potential road identification

This paper investigated the validation of a multi-criteria method for identifying potential roads, and demonstrated the capability of analyzing GPS vehicle tracking data for identifying vehicle movement patterns and potential roads. The multi-criteria method was evaluated by comparing the predictions to the site visit results on 34 selected road segments meeting different criteria levels. Results show that locations meeting higher criteria levels have higher possibilities to be roads: an approximately 91% possibility of road existence for the locations meeting all five criteria; 55% for the locations meeting four criteria; and 14% for those meeting criteria level two or three. This approach provides an opportunity for land managers to update existing GIS roads map, or identify newly formed roads that may need either rehabilitation or inclusion into the roads maintenance program.     

一种摩擦学状态在线监测系统的研究

研制了一种用于船用柴油机的摩擦学状态在线监测系统。它集磨粒监测，润滑油质量监测，柴油机扭矩及时转速监测于一体，利用在线铁谱技术监测润滑油中的铁磁性磨粒，利用容栅型电容传感器在线监测污染物引起的润滑油介电常数的变化，利用光电传感器和随轴转动齿盘产生的脉冲及相位差在线测量柴油机输出轴的扭矩及瞬时转速。此外，该监测系统还可将柴油机的磨损状态与动力状态相关联，监测由于各缸爆排压力变化造成的瞬时转速变化，从