水流损失和热补偿共同作用对增强型地热系统(EGS)产能影响的研究

基于青海共和盆地-3705m地热田实测数据,结合流固耦合传热理论并运用Comsol软件,建立了离散型裂隙岩体流体传热模型。考虑水流损失和热补偿共同作用,模拟得到了开采过程中上、下岩层(盖层和垫层)为绝热不渗透、传热不渗透、渗透传热时,储层(上、下岩层和压裂层)温度场的变化特征,分析了产出流量、水流损失、产出温度、产热速率的变化规律。研究结果表明:采热过程中产出流量始终小于注入流量;产出流量增幅速率先增大后减小,最后趋于稳定,前3a产出流量增幅超过总增幅量的3/4;忽略水流损失,将高估产热速率,采热初期甚至达到考虑水流损失时产热速率的3倍以上;考虑水流损失,产热速率呈先快速上升再趋于稳定后逐渐下降的趋势,最优开采时间为3a^11a;研究上、下岩层对产出温度的影响,仅考虑传热,采热寿命延长5.43%,同时考虑渗流传热时,采热寿命延长2.71%;采热前9a,水流损失占主导作用,即流入上、下岩层水流损失对产热速率的影响高于热补偿效应,开采10a后,热补偿效应占主导作用;同时考虑水流损失和热补偿效应得到的产热速率变化规律与实际工程更为符合,建议选择低渗透能力的上、下岩层延长增强型地热系统(EGS)运行时间。     

煤(岩)体埋深及倾角对压应力型冲击地压的影响研究

为了研究不同埋深和煤岩倾角对煤岩体开采引起的压应力型冲击地压过程,利用颗粒流方法进行冲击地压模拟。煤岩体与顶板倾角工况设置为7种,分别为0°,5°,10°,15°,20°,30°和40°;煤岩层埋深深度设置为8种,分别为-120m～-820m,间隔100m。在上述56种工况下进行压应力型冲击地压过程模拟,计算至平衡时统计飞石颗粒数量和变形颗粒数量,研究这两个数量与埋深和倾角之间的关系。结果表明,飞石数量和变形颗粒数量与埋深均为幂函数关系,前者随倾角增加幂次数增加且均大于1,后者随倾角增加幂次数增加但均小于1;在深度不变时两者数量增长与倾角为线性关系,且随着深度增加,斜率和截距均增加。     

混合及流体动力润滑下规则微小凹痕图型表面的摩擦特性研究

采用销-盘摩擦副接触方式在混合及流体动力润滑下,对不同密度的规则微小凹痕图型表而进行石蜡油润滑下的摩擦试验,利用Stribeck曲线分析在不同试验条件下,不同密度的规则微小凹痕图型表面的摩擦特性,利用摩擦系数曲线图解析不同载荷和滑动速度下,不同密度的规则微小凹痕图型表面的摩擦行为.结果表明,当试样表面具有规则微小凹痕图型时,其减摩效果较无微小凹痕图型表而更佳,在不同载荷作用下,规则微小凹痕图型存在着最佳的密度分布,即在载荷为5～30N,规则微小凹痕图型密度为32.4%时的减摩效果最佳.     

关于非完整系统的Lagrange型方程——————分析力学札记之十

 研究五类特殊非完整系统, 它们的运动微分方程有Lagrange形式.     

混联Ⅰ型惯容系统基于李鸿晶谱的地震响应分析

针对设有混联Ⅰ型惯容系统的耗能结构基于李鸿晶谱的响应分析较为繁琐的问题,提出求解地震响应的简明封闭解法,并研究了惯容系统基本参数对减震性能的影响。首先,建立惯容系统和结构之间的微分型本构关系,并运用复模态法和虚拟激励法获得结构系列响应的统一解。其次,将结构系列响应的功率谱密度函数精确转化为复特征值及结构自振频率平方和表示的二次分解式,进而获得响应0阶～2阶谱矩的简明封闭解。最后,通过数值算例验证了所提方法的正确性及计算的高效性,对惯容系统参数的研究表明,当惯容系数和阻尼系数越大,结构减震效果越好,而刚度系数对结构的减震效果取决于惯容系统名义圆频率与结构自振圆频率的比值,当两者比值为0.9时减震效果最好。     

分布式光纤传感测试系统(BOTDA)用于H型钢梁变形监测的实验研究

介绍了分布式光纤传感测试系统(BOTDA)的应变测量原理,并应用BOTDA技术对H型钢梁加载后的应变分布进行了测量。试验表明,BOTDA的应变测量结果与电阻应变片的测量结果及理论值具有良好的一致性。光纤测量的数据是连续的,因而更加适用于那些需要测试连续变形的结构。由BOTDA的实测应变分布推算出的H型钢梁的弯矩和挠度,与理论分析结果高度吻合。作为先进的监测技术手段,分布式光纤传感测试系统应用于SMW工法桩施工监测是完全可行的。     

一类 Duffing 型系统的不动点混沌和Fold/Fold 簇发现象及机理分析

本文主要探究了一类含有两个慢变量的双稳态 Duffing 型系统,通过时间历程图、相图、分岔图等对系统进行数值模拟,然后从理论上分析不同参数下系统的动力学机理. 首先,研究发现当振幅参数取值大于 1 时,系统会表现出不动点混沌现象,并进一步解释了产生不动点混沌的机理. 其次, 介绍了参数空间中的簇发振荡现象,即系统穿过鞍结曲面的一侧到达另一侧所发生的行为,这里也称为鞍结簇发振荡. 事实上,当系统穿过鞍结曲面的时候,它的平衡点个数发生了变化. 然后,使用纵向抛物线路径说明了 Fold/Fold 簇发振荡产生的机理,发现无论常系数项和振幅的取值为多少,只要满足一定的关系,总会产生 Fold/Fold 簇发振荡,之后使用线性路径阐明了新增常系数项会使得系统发生簇发振荡的原因. 并且发现路径与鞍结曲面交点的位置会影响簇发振荡的对称性;路径的跨度会影响簇发振荡的大小. 最后,使用多拐折曲线路径讨论当两个激励项存在 $n$ 倍关系时系统产生的现象. 结果表明当 $n=3$ 时,常系数项的变化会使得系统表现出不同重数的 Fold/Fold 簇发振荡,最高可达到三重簇发振荡. 并且发现在理想状况下如果可以找到一条路径可以分割为 $n$ 段,并且每一段都会与鞍结曲面有交点,那么会产生 $n$ 重 Fold/Fold 簇发振荡.      

Advanced Turbulence Modelling of Separated Flow in a Diffuser

The paper describes an investigation into the predictive performance of linear and non-linear eddy-viscosity models and differential stress-transport closures for separated flow in a nominally two-dimensional, asymmetric diffuser. The test case forms part of a broader collaborative exercise between academic and industrial partners. It is demonstrated that advanced turbulence models using strain-dependent coefficients and anisotropy-resolving closure offer tangible advantages in predictive capability, although the quality of their performance can vary significantly, depending on the details of closure approximations adopted. Certain features of the flow defy resolution by any of the closures investigated. In particular, no model resolves correctly the flow near the diffuser's inclined wall immediately downstream of the inlet corner, which may reflect the presence of a “flapping” motion associated with a highly-localised process of unsteady separation and reattachment. This revised version was published online in July 2006 with corrections to the Cover Date.     

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。     

水模拟连铸结晶器中流速值的氢气泡测试方法

为了获得连铸结晶器中钢液的流速值，以验证数学模拟结果，本文用相似准则原理设计的水模拟板坯连铸结晶，将氢气泡测试技术首先用于其中流速的定量测定，利用氢气泡团的时间－脉线组合图谱所提供的时间－位移信息，测定了不同拉速下水模拟结晶器中若干点的速度及分布，对发泡阴极丝的定位方法和测量位置选择进行了描述，总结了试验中的经验。     

水动力试验和流噪声测试

在模型表面上涂敷低表面能涂层会降低航行体阻力和噪声．因此，对水筒中流噪声的测量数据重复性、误差和数据的可信度等，必须有正确的测量和分析方法．在相同时期内，用相对比较法，从模型内测量同一模型的流噪声，其测量数据的重复性好，误差小于２ｄＢ．在８ｋＨｚ４０ｋＨｚ频率范围内，水筒中环境所造成的背景噪声小，这时信噪比大，噪声的测量能较好地反映出涂层的降噪效果．而低频时≤５ｋＨｚ，循环系统引起较高的背景噪声，可能会掩盖涂层的降噪效果．但低频时，相对比较法中，噪声的降低确是涂层引起的结果．     

Simulation and Modelling of Turbulent Trailing-Edge Flow

Computations of turbulent trailing-edge flow have been carried out at a Reynolds number of 1000 (based on the free-stream quantities and the trailing-edge thickness) using an unsteady 3D Reynolds-Averaged Navier–Stokes (URANS) code, in which two-equation (k–ε) turbulence models with various low-Re near wall treatments were implemented. Results from a direct numerical simulation (DNS) of the same flow are available for comparison and assessment of the turbulence models used in the URANS code. Two-dimensional URANS calculations are carried out with turbulence mean properties from the DNS used at the inlet; the inflow boundary-layer thickness is 6.42 times the trailing-edge thickness, close to typical turbine blade flow applications. Many of the key flow features observed in DNS are also predicted by the modelling; the flow oscillates in a similar way to that found in bluff-body flow with a von Kármán vortex street produced downstream. The recirculation bubble predicted by unsteady RANS has a similar shape to DNS, but with a length only half that of the DNS. It is found that the unsteadiness plays an important role in the near wake, comparable to the modelled turbulence, but that far downstream the modelled turbulence dominates. A spectral analysis applied to the force coefficient in the wall normal direction shows that a Strouhal number based on the trailing-edge thickness is 0.23, approximately twice that observed in DNS. To assess the modelling approximations, an a priori analysis has been applied using DNS data for the key individual terms in the turbulence model equations. A possible refinement to account for pressure transport is discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Simulation and Modelling of a Skewed Turbulent Channel Flow

A time-dependent three-dimensionally skewed flow is investigated using direct numerical simulations of the incompressible Navier-Stokes equations. The effect on the instantaneous and mean turbulent field is investigated. Instantaneous flowfields reveal that the skewing has the effect of initially reducing the strength and height of quasi-streamwise vortices of both signs of rotation with respect to the skewing. A mechanism for this process is put forward. The mean flowfields show drops in turbulence quantities such as turbulence kinetic energy. In addition to this, two-equation turbulence modelling of the flow is carried out. This highlights a deficiency, in that the standard turbulence models are unable to capture the drop in turbulence intensity due to the skewing. A modification based on the exact dissipation equation is found to significantly improve the model behaviour for this flow. This revised version was published online in July 2006 with corrections to the Cover Date.     

油水重力分离实验模拟系统的研制

所研制的油水重力分离实验模拟系统，由介质循环、乳化液制备、激光片光源、图象采集及设备模型等部分组成，可对系统流量、介质物性、分散相含量、乳化状态、设备结构等多种因素进行实验模拟，从而能有效地将实际介质在工程设备中的流动与分离过程再现到实验室中．该系统与ＰＩＶ、停留时间分布等有关检测技术相配合，可对多种油田地面分离设备进行多工况、多参数的流动诊断分析，为揭示介质在设备中的流动与分离规律、研究设备工作理论、优化设备结构等提供了重要手段．     

Computational Modelling of Non-Newtonian Effects on Flow in Channels with Moving Wall Indentations

Non-Newtonian effects in a channel with moving wall indentations are assessed numerically by a finite volume method for solving the unsteady incompressible Navier-Stokes equations and using a power-law model exhibiting shear thinning viscosity and Casson's model as the constitutive equations for the non-Newtonian fluid. The computations show that for a non-Newtonian fluid, there are differences in the velocity profiles and in the structure and size of the reversed flow regions as compared with the corresponding Newtonian fluid. The comparison of non-Newtonian and Newtonian wall shear stress reveals a slight decrease in the magnitude on the average for the non-Newtonian case, eventually resulting in the strength of the “wave train” being slightly weaker than those corresponding to a Newtonian fluid.     

平面粘性流体扰动与哈密顿体系

通过变分原理,将哈密顿体系的理论引入到平面粘性流体扰动的问题中,导出一套哈密顿算子矩阵的本征函数向量展开求解问题的方法。基于直接法求解流体力学基本方程,导出流场一般特征关系,通过本征值的求解及本征向量的叠加,得到波扰动解,继可分析流场端部效应。从而在该领域用在哈密顿体系下辛几何空间中研究问题的方法代替了传统在拉格朗日体系欧几里德空间分析问题的方法。为流体力学的研究提供一条新途径。     

激光片光源技术在水垫塘流场显示中的应用

文中研制了一套以激光作片光源的流场显示装置，并对单股和双股射流水垫塘流场进行了可视化研究．流场显示表明：双股射流的水垫塘流动结构可划分为六个区域，比通常的单股射流塘内水流结构增加了股间混掺区和“动水垫”影响区两个流区．分析讨论指出，双股射流入塘后水舌扩散加快和产生动水垫效应是其流态优于单股射流的两个显著特征．本文成果将为以降低塘底动水压强和充分发挥水垫塘消能效率为目标的水垫塘优化设计与计算提供指导和依据