内燃机缸内全流场PIV测速系统

本文针对内燃机缸内气流运动研究需要，在国内首次开发研制出一套内燃机缸内全流场ＰＩＶ测速系统。该系统具有全透明的气缸体和活塞，激光器发光孔可３６０°旋转，配以灵活的光路调节装置和拍摄装置。可对内燃机整个工作范围内的缸内流场进行全视野测量。     

动态模态分解方法在缸内湍流场研究中的应用

内燃机缸内湍流场在内燃机的工作过程中扮演着极为重要的角色,对该特殊流场的分析除了需要精确的记录还需要科学的数学分析方法.该研究作为一种尝试,应用动态模态分解方法(DMD)对内燃机缸内流场采用粒子图像测速(PIV)测量数据库进行加工,研究缸内流场在不同频率下的流动特性,包括不同频率下涡团结构形态及其空间分布、能量/强度的分布及其耗散情况,从而有利于丰富人们对内燃机缸内湍流场特性的认识.     

激光技术在内燃机缸内流动实验研究中的应用

内燃机缸内流场实验是研究内燃机缸内流动规律最直接有效的方法 ,先进的激光技术以其特有的优点为内燃机测试和缸内流场实验研究提供了新的手段。本文介绍了激光技术在内燃机缸内流场实验研究中的应用和最新进展 ,以及作者应用PIV技术进行汽油机缸内流场测试的尝试     

激光技术在内燃机缸内流动实验研究中的应用

内燃机缸内流场实验是研究内燃机缸内流动规律最直接有效的方法,先进的激光技术以其特有的优点为内燃机测试和缸内流场实验研究提供了新的手段。本文介绍了激光在内燃机缸内流场实验研究中的应用和最新地 ,以及作者应用ＰＩＶ技术进行汽油机缸内流场测试的尝试。     

内燃机缸以流场的全场测试实验研究

传统的单点测量技术只能获得流场中某一点的瞬时流速，对于非稳态的内燃机缸内流场，这显然是不够的。本将粒子图像测速技术用于研究内燃机缸内流场，可以测定某一瞬时的缸内流场全场流速分布。开发成功的实验装置可模拟四冲程发动机的缸内流动，并适合于粒子图像测速技术来测定缸内及燃烧室内的流场。实验系统采用短间隔多脉冲激光，便照相底片曝光来拍摄流场照片，然后用ＰＩＶ照片分析处理系统对其显微放大，直接读取示踪粒子的     

内燃机缸内流场的全场测试实验研究

传统的单点测量技术只能获得流场中某一点的瞬时流速，对于非稳态的内燃机缸内流场，这显然是不够的。本文将粒子图像测速技术用于研究内燃机缸内流场，可以测定某一瞬时的缸内流场全场流速分布。开发成功的实验装置可模拟四冲程发动机的缸内流动，并适合于用粒子图像测速技术来测定缸内及燃烧室内的流场。实验系统采用短间隔多脉冲激光，使照相底片曝光来拍摄流场照片，然后用ＰＩＶ照片分析处理系统对其显微放大，直接读取示踪粒子的位移，使粒子像对的判别更准确容易。实验结果表明，这种实验系统是可行而实用的。     

用热线风速仪测量内燃机缸内流场时热线探针的方向敏感性研究

在应用热线探针测量内燃机缸内空间流场时，探针的方向敏感性受到许多因素的影响，本文介绍了在气流试验台上对几种结构进行的方向敏感性因素（气流速度，。方向偏角，支杆倾角等）试验。总结了各种因素变化时可能产生的热线测值偏差及其修正方法；观察分析了产生这些偏差的主要原因，主要是气流在热线支柱影响下生成的旋涡和流动死区，最后，介绍了用热线探针在一台二行程直流扫气柴油机上进行的缸内流场稳态分布测量结果。     

单片机在内燃机瞬时转速测量中的应用

从分析内燃机瞬时转速的测量原理入手,论述了内燃机瞬时转速的测量现状及存在的不足,并通过实验把AT89C51单片机应用于内燃机瞬时转速的测量中,实现了数据的存储与发送,满足了不同的瞬时转速的测量要求。     

单片机在测量内燃机瞬时转速中的应用

从分析内燃机瞬时转速的测量原理入手，论述了内燃机瞬时转速的测量现状及存在的不足，并通过实验把AT89C51单片机应用于内燃机瞬时转速的测量中，实现了数据的存储与发送，满足了不同的瞬时转速的测量要求。     

单片机在测量内燃机瞬时转速中的应用

从分析内燃机瞬时转速的测量原理入手,论述了内燃机瞬时转速的测量现状及存在的不足,并通过实验把AT89C51单片机应用于内燃机瞬时转速的测量中,实现了数据的存储与发送,满足了不同的瞬时转速的测量要求。     

基于圆管层流对流传热模型的温度场推算三元非共沸混合物组分方法的研究

给出了一种利用测定圆管对流传热温度场求解确定成分的非共沸混合物的组分的方法。基于定压力条件下液体低雷诺数圆管层流充分发展段流体力学特性,利用数值方法求解变热参数对流传热模型温度场特性,采用反问题方法对对流传热控制方程的热参数进行非线性模拟和反算,通过反演计算热参数得到物质组分的定量值。对非线性热参数条件的对流传热控制方程和反问题L-M方法进行了误差分析,通过试验比较,测定了对流传热过程温度场的理论计算组分与预设的组分。结果表明,测定温度场推算的非共沸混合物组分与实际测定结果满足预设误差。     

Characterization of the temperature oscillation technique to measure the thermal conductivity of fluids

The temperature oscillation technique to measure the thermal diffusivity of a fluid consists of filling a cylindrical volume with the fluid, applying an oscillating temperature boundary condition at the two ends of the cylinder, measuring the amplitude and phase of the temperature oscillation at any point inside the cylinder, and finally calculating the fluid thermal diffusivity from the amplitude and phase values of the temperature oscillations at the ends and at the point inside the cylinder. Although this experimental technique was introduced by Santucci and co-workers nearly two decades ago, its application is still limited, perhaps because of the perceived difficulties in obtaining accurate results. Here, we attempt to clarify this approach by first estimating the maximum size of the liquid’s cylindrical volume, performing a systematic series of experiments to find the allowable amplitude and frequency of the imposed temperature oscillations, and then validating our experimental setup and the characterization method by measuring the thermal conductivity of pure water at different temperatures and comparing our results with previously published work.     

国内泡沫钻井流体应用与研究进展

综述泡沫钻井流体在国内的现场应用及室内研究,总结泡沫钻井流体的优点和不足.泡沫钻井流体具有密度低、滤失量小、携岩能力强和机械钻速高等特点,对于衰竭、水敏性地层有着广泛的应用前景,已成为油气田开发过程中钻井流体的一个重要发展方向.指出泡沫钻井流体在井壁稳定方面具有独特优势,为稳定井壁提供了新的技术手段；同时,也存在泡沫体系稳定性差、现场消泡困难以及井壁稳定评价方法欠缺等问题.以工程应用和室内研究为两条主线,介绍泡沫钻井流体在我国的应用进程和研究进展.最后指出,加强对泡沫钻井流体的认知和研究,进一步开发和优选发泡剂、稳泡剂,提高体系稳定性；增加消泡技术研究,促进泡沫钻井流体的可循环利用；研究抑制剂、井壁稳定剂,建立专用的室内井壁稳定评价方法和统一的标准,促进泡沫钻井流体在国内的进一步推广应用.     

某汽油机改型前后机体温度场计算分析

直接流热耦合法将机体及与其相互作用的固体和流体部分作为一个整体进行研究,将难以确定的外部边界条件转化为内边界,通过能量守恒的方法在固-液交界面上自动完成热量交换。本文使用CFD软件STAR-CD,利用建立的机体、气缸盖和冷却水套组成耦合模型,采用直接流热耦合方法计算了某汽油机改型前后的机体温度场,计算结果和实验值吻合得较好,这反映了直接耦合法计算机体温度场有足够的精度。依据计算结果,本文对改型前后的机体温度场进行了详细地分析。     

A new and fast method to determine mixing and conductive cooling of thermal waters in carbonate-evaporite environments

A method is proposed, for low-temperature geothermal systems, for calculating the aquifer temperature and relative proportions of mixed thermal and shallow groundwaters from carbonate-evaporite environments. The fluid is assumed to be in chemical equilibrium with anhydrite and chalcedony in the aquifer, and mixed with diluted waters during its ascent. An attempt has been made to establish a relationship between reservoir temperature, the aqueous sulfate and silica contents of the mixed fluid, the proportion of the thermal end-member and the temperature of the adiabatic mixture. The method calculates mineral solubilities in the field context, calibrated on representative thermal springs. The method also considers the effects of conductive cooling.     

Incidences of aligned magnetic field on unsteady MHD flow past a parabolic accelerated inclined plate in a porous medium

An exact analysis of a radiative hydromagnetic flow behavior over a tilted parabolic plate through a permeable medium along with variable species concentration and fluid temperature in the presence of a slanted magnetic field parameter, chemical reaction, and heat generation has been carried out in this study. Closed-form analytical benchmark solutions for flow-governing equations are obtained by using the Laplace transform method. Thereafter, the incidences of different important physical entities on the nondimensional velocity field, temperature distribution, and species concentration are presented using graphs, whereas impacts of various physical entities on wall shear stress, heat and mass transfer rates are presented in tables. It is worth noting that an increase in the magnetic field and its inclination angle causes the reduction in the fluid velocity. However, wall shear stress increases with the increase of magnetic field and its inclination angle. The novel results in this article can be used to improve quicker cooling and producing miniaturized heat flow systems with upgraded efficiency and cost-effectiveness.     

汽机阀壳瞬态温度场及应力场仿真分析

采用结构分析有限元方法,对某型汽轮机阀壳冷态启动工况下的温度场、热应力场及综合应力场进行了分析计算,得出了关键点处详细的温度场及其对应的热应力场的变化规律,并估算了关键点处阀壳疲劳寿命.分析过程中采用CFD软件对阀壳内部流质速度场进行了仿真模拟.     

Impacts of low harm fracturing fluid on fossil hydrogen energy production in tight reservoirs

The polymer fracturing fluid has been gradually used in the fossil hydrogen energy field. However, its impacts on the fields are still unclear. In this study, a series of experiments were conducted to solve the problem. First, a new method called the pressure transmission test (PTT) was used to evaluate the permeability damage induced by polymer fracturing fluid. Then several rock properties were tested to reveal rock potential damage induced by the aqueous fracturing fluid, after that the interactions between polymer fracturing fluid and rock were discussed in detail. Results showed that the average permeability pollution is 10.6. Permeability and X-ray diffraction (XRD) tests stated that the core is easier to be blocked by particles in the formation or fracturing fluid residue. Blocking and scanning electron microscope (SEM) tests showed that the nanoscale polymer would stick on the rock surface, and reduce the pore size. Our work provides a new method to evaluate the impact of polymer fracturing fluid on tight reservoirs. Moreover, the mechanism of permeability damage caused by the polymer fracturing fluid was also revealed.     

Numerical and linear regression analysis on MHD two-phase flow in an asymmetric nonuniform channel

The flow through asymmetric nonuniform (convergent) channels with the effect of the magnetic field have a pronounced impact in engineering and biological fields such as chemical and food industries, blood flow through capillaries, and arteries, and so forth. With this motivation, the present study focuses on convective hydromagnetic particulate suspension flow in an asymmetric convergent channel under the heat generation effect. The numerical method is applied to solve the nondimensionalized equations governing the transport process of fluid and particle flow and its heat. To check the convergence of the computational results, a grid independence test has been performed. A comparison test has been made to validate the results and an admirable agreement is noticed with published results. Computation results are reported for the influence of emerging parameters on the fluid as well as particle velocity and temperature profiles through graphs and tables. A method of slope linear regression through data points is presented to study the impact of various parameters on skin friction and Nusselt number. The study pioneers the investigation on the significance of the combined influence of cross-flow Reynolds number and magnetic field on fluid and particle in the convergent channel and also reports its importance on drag coefficient and rate of heat transfer at the walls. It is perceived that a reduction in fluid velocity takes place with an increment in Magnetic parameter, Grashof number, and Reynolds number. An augmentation in fluid temperature is noted with an increment in Prandtl number and heat source parameter.     

Calculation of heat transfer in turbulent flow with allowance for secondary flow

Calculation method is proposed for the determination of the temperature field in a fluid in noncircular ducts. The calculation results are given for the case of turbulent flow in a square duct. For comparison results of measurements are presented of a temperature field in fluid flow under conditions close to those assumed in the calculations.