基于分布式光纤温度传感技术的渗流监测试验

为实现实时、长距离和分布式的渗流监测,基于分布式光纤温度传感技术定位原理,设计了室内渗流监测模型及理想的提高渗流监测空间测量精度的光纤布置方式,通过对埋置于粘土、砂土以及均匀混合土壤中的光纤进行加热模拟渗流试验,对比分析不同渗流量下光纤温降情况,说明光纤布置方式的合理性及渗流定量监测的可行性,并给出了提高温度测量精度及压实效果的有效措施。     

旋转圆筒表面对流质交换边界层实验研究

用微热偶式干湿球温度计．在稳定对流质交换状态下,对水平旋转圆筒多孔介质表面边界层的温度场和浓度场进行了测量。实验表明：对流质交换边界层的厚度随船,的增大而减小;浓度边界层的厚度大于温度边界层的厚度;热质交换边界层的温度梯度小于纯对流热交换边界层的温度梯度;旋转对于顺向侧和逆向侧对流质交换的影响结果不同．在顺向侧．由于旋转受迫对流和自然对流的作用方向一致,二者相互叠加的结果,使得边界层浓度梯度加大,厚度减小,而在逆向侧,情况则正好相反。     

渗流对竖直地埋管换热器换热性能的影响

为了确定渗流对竖直地埋管换热器换热性能的影响,基于多孔介质传热理论与Darcy定律,利用多物理场耦合软件COMSOL建立了三维热渗耦合模型,模拟了有无渗流条件下竖直地埋管换热器周围土壤温度场的变化。结果表明,地下水渗流有助于竖直地埋管换热器换热,且渗流速度越大,竖直地埋管换热器换热效果越明显;平行于渗流方向处温度场偏向下游,垂直于渗流方向处温度场始终保持对称分布,渗流速度由0m/s增大到1.0×10-5 m/s时,对应热作用半径由0.42m减小到0.32m。     

发射率结合辐射光强实时测量高温辐射源2维温度场

提出了一种由光纤光谱仪与黑白CCD相机构成的新型实时在线高温温度场测量系统.该系统用光纤光谱仪和黑白CCD相机同时测得高温辐射源的真实发射率和光强场,然后根据发射率和光强场计算得到高温辐射源的温度场.利用该系统对高温发光物体——卤素灯灯丝的温度场进行测量,得到了不同电压值下卤素灯灯丝的温度场分布图,并将所得温度场的最高温度与相应工况下发射光谱法测量得到的最高温度进行比较.结果表明:两者相对偏差在5%以内;所提出的测量方法既弥补了发射光谱法不能获得场分布的缺陷,又避免了比色法测温中单色波长带宽和发射率瞬时变化带来的误差,是一种有效的温度场测量方法.     

三道湾水电站坝基渗流分析

在无量水堰的前提条件下,为监测三道湾水电站坝基渗流量,在坝后覆盖层中布设测压管监测系统,在满足一定误差要求的条件下,依据水力坡降法推导出三道湾水电站坝后河床渗流量计算公式,计算得出2012年汛期坝后河床平均渗流量为58.06 L/s,并基于坝后渗流的影响因素,提出增设坝肩绕渗监测系统的建议。     

T91/TP347H异种钢焊接接头蠕变行为分析及寿命预测

在恒定温度、不同应力下进行了T91/TP347H异种钢焊接接头的高温蠕变实验.采用修正的θ投影模型来描述T91/TP347H异种钢焊接接头的蠕变性能,结合蠕变断裂经验公式推导出最小蠕变速率的解析表达式,并提出了新的蠕变寿命预测模型.结果 表明:采用修正的θ投影模型得到的蠕变曲线拟合值与实验值吻合良好,可准确地表达出蠕变曲线3个阶段的特性;所提出的蠕变寿命预测模型的预测误差在5％之内,预测精度较好.     

基于地下水渗流的地埋管土壤温度场分析

基于有限长线热源模型,考虑地下水的渗流作用,对比分析无渗流工况与渗流工况下地下土壤温度场分布,结果表明:地下水渗流有利于地下热量的扩散,渗流工况下平均温度与最高温度较无渗流情况分别下降约5℃、4℃,温度场的热量累积得到抑制和减缓;并分析长方形埋管布置形式下的土壤温度场,讨论不同方向的地下水渗流工况对地下土壤温度场分布的影响,对于横纵向埋管数量不同的管群,沿埋管数量少的方向渗流,其土壤温度降低更显著。     

地下水流动对垂直埋管换热器土壤温度场分布的影响

为确定地下水渗流对地下埋管换热器周围土壤温度场的影响,基于内热源法建立热渗耦合作用下的数学模型,利用传热模拟得到换热器周围土壤温度场分布,结果表明地下水流动对原温度场影响明显,而且地下水流速越大影响越大。     

用于研究柴油机缸内燃烧火焰对壁面热边界层影响的光纤传感器及测量系统

为了研究缸内燃烧火焰对热边界层的影响,研制开发了贯穿式光纤传感器及测量系统,在此基础上初步研究了柴油机气缸内燃烧火焰对缸内壁面的热边界层的影响,结果表明,该传感器可以较好地用于测量缸内壁面热边界层中任一位置的火焰温度。     

基于LBM-MFLS耦合模型的含水层渗流-传热过程模拟

基于有限长移动线热源(MFLS)传热模型，根据时空叠加原理推导出含水层非稳态过余温度解析解Δ_TMFLS；在格子单松弛模型(LBGK)的演化方程中引入离散力源项，建立格子Boltzmann法(LBM)与Δ_TMFLS的耦合计算模型。通过热响应实验，验证耦合计算模型与求解方法的正确性。研究表明，在不同计算工况下含水层各区域的渗流速度均具有启动—下降—回升—稳定的4个连续阶段。随着含水层孔隙率的降低，虚拟流体粒子动能损失增大，渗流速度降幅增大，回升过程缓慢。然而随着进水流速的提高，孔隙率的变化对于含水层水动力场演化过程的影响程度减弱；含水层热量运移过程的方向性显著增强。     

边界层理论在陡坡坡面流速计算中的应用

坡面流是研究土壤侵蚀机理的关键,流速计算受多因素影响尤显复杂,为此提出了应用陡坡紊流边界层名义厚度方程求解坡面流流速的分布,探讨了经典边界层理论模型,修正了传统边界层的势流流速,推导出适用于描述坡面流流动特性的理论模型,考虑到下垫面及水温等的影响,构建了分类计算平均流速的计算模型,并验证了计算模型的可行性。     

柴油机缸内近气缸盖壁面边界层预测模型的研究

分析了缸内壁面速度边界层和热边界层的形成过程,建立了缸内近气缸盖壁面面湍流速度壁面函数和温度壁面函数,研究了边界层内的速度分布、温度分布及速度边界层厚度和热边界层厚度,并将预测结果与拖动发动机的实测值进行了比较,发现两的趋势是一致的。研究结果表明,缸内近气缸盖壁面有边界层形成,同一位置的速度边界层与热边界层的厚度很接近,不同位置的边界层厚度不同,大约在2mm-4mm左右。     

Unsteady mixed convection from a rotating vertical slender cylinder in an axial flow

Unsteady mixed convection flow over a rotating vertical slender cylinder under the combined effects of buoyancy force and thermal diffusion with injection/suction has been studied where the slender cylinder is inline with the flow. The effect of surface curvature is also taken into account, especially for the applications such as wire and fiber drawing, where accurate predictions are desired. The governing boundary layer equations along with the boundary conditions are first converted into dimensionless form by a non-similar transformation, and then resulting system of coupled nonlinear partial differential equations is solved by an implicit finite difference scheme in combination with the quasi-linearization technique. The effects of various parameters on velocity and temperature profiles and on skin friction coefficients and heat transfer rate at the wall are reported in the present study.     

基于蛇形分布式新型光纤布型设计的堤防浸润线定位

针对传统直线形光纤布型无法满足水利工程中浸润线测量要求的问题,根据测温光纤测点定位特点,设计并制作了一种蛇形分布式浸润线监测的新型光纤,以提高其定位精度。通过水深测量试验进行堤防浸润线定位,计算水深与实际水深对比结果表明,光纤新布型定位具有较高精度。研究成果可为工程应用提供参考。     

Forced Convection Laminar Film Condensation of Downward Flowing Vapor on a Single Horizontal Elliptic Cylinder or a Bank of Elliptical Tubes

A numerical study is performed on the laminar film condensation of pure saturated vapor flowing in the direction of gravity on a single horizontal elliptic cylinder or a bank of elliptical tubes. Temperature, velocity distribution, and heat transfer coefficient of the fully developed flow are carried out with a fully implicit finite difference scheme. The equality of shear stress at the liquid-vapor interface is used as the coupling condition between the two phases. The inertia and convection term are retained in the analysis. Outside of the vapor boundary layer, the vapor phase velocity is obtained from potential flow. The method of source density distribution on the body surface is used for determination of the external vapor velocity in elliptical tube banks. The effect of inundation produced by condensate on upper ellipses is taken into account by assuming that the vapor velocity field is not affected by the condensate flow from one elliptic cylinder to another. Based on the obtained solutions of flow field, the effect of surface tension, the interaction because of the ellipse spacing, and the inundation on the heat transfer coefficient and the boundary layer separation point have been evaluated. The results of this analysis are discussed especially in function of eccentricity e (effect of the surface tension). The heat transfer in interellipse space is analyzed and compared with the theoretical and experimental results of other authors. Good agreement is shown.     

ADINA软件在土石坝渗流场计算中的应用

根据基本方程及定解条件的比较分析,将AD INA软件的温度场模块分析功能应用于渗流场的分析,并采用死活单元技术,通过迭代算法计算自由水面位置(浸润线),解决了实际工程观音岩心墙土石坝渗流稳定问题的求解。该方法可以解决复杂边界、多种介质的渗流问题,为实际工程设计应用提供强有力的途径。     

Scalar transport in a quasi two-dimensional turbulent wake interacting with a boundary layer

An experimental study of heat transport in the interaction region between the wake of a cylinder and a turbulent boundary layer is presented in this work. The cylinder was placed parallel to a flat plate and normal to the flow. Its position was selected above the boundary layer edge, so that the lower part of the wake was interacting with the boundary layer. Heat was supplied to the boundary layer flow by means of a line heat source. Presence of surface roughness on the cylinder resulted in the deviation of the velocity power spectrum scaling region from the −5/3 power law which is characteristic of three-dimensional turbulence. Point measurements of the instantaneous values of two velocity components and temperature have been taken using hot-wire anemometry. Two turbulent scalar flux components and a Reynolds shear stress component have been obtained directly from the experimental data. Results were assessed in conjunction with the periodic coherent structures in the wake (a von Kármán vortex street) using a phase-averaging technique that provided a clear picture of the heat transport procedures involved.     

Correlation of spherical thermistor for the measurement of low velocity air flow

A spherical thermistor, an accurate temperature sensor, is employed as an air velocity sensor in this work. The measuring principle is derived and the effects of the insulation layer, air temperature, natural convection and thermal radiation are discussed. Two different correlation relations for velocity measurements are proposed based on theoretical analyses and experimental calibrations. Experiments have shown that spherical thermistor is a good velocity sensor for speed between 0.1–2.5 m/s at room temperature and the insulation layer hardly influences the accuracy of the thermistor used in the present work. Modification on correlation can even further improve measurement accuracy. Since the thermistor is small and cheap, it is possible to apply this method to multi-point velocity measurement with a low disturbance to the flow field.     

考虑沸腾和缸内局部传热的缸盖流固耦合传热分析

以某商用车直列6缸柴油机作为研究对象,基于缸内传热模型获得内燃机缸盖和缸套的燃气侧局部传热边界条件;基于均相流沸腾传热模型获得水侧传热边界;实现水侧、燃气侧边界与结构温度场计算的耦合,并判断水腔内沸腾传热的状态。结果表明:缸盖温度计算值与实测值吻合,缸盖最高温度位于缸盖底面两个排气门之间;排气门之间的燃气传热系数和燃气温度均处于较高值,缸内局部传热显著;在缸盖底面中心和排气门附近水腔内的冷却水处于部分发展泡核沸腾状态。