三声道燃油超声波流量计内部流场数值研究

针对三声道燃油超声波流量计圆截面多弯曲管道,基于不可压缩雷诺时均Navier-Stokes方程建立流量计管道内计算流体动力学仿真模型。使用重整化群k-ε湍流模型、有限容积法和结构化网络进行离散化,并在近壁区采用标准的壁面函数法修正,完成对三声道燃油超声波流量计的管道内部湍流的数值模拟。数值研究结果表明,在8种不同进口速度条件下,3个声道的流场沿中心线均是不均匀分布;H-H声道流场变化最大,P-P声道流场最平稳;P-P声道测量精度最好,而H-H声道测量精度最差。     

涡轮流量计内部流场数值模拟研究

利用数值仿真技术对涡轮流量计内部流场进行了研究,目的是为优化涡轮流量计的结构设计提供指导。利用叶轮转速与平均力矩系数存在线性关系,提出两点法确定叶轮在力矩达到平衡状态下的转速。数值分析结果表明,前导流件叶片后形成的尾流影响叶轮人口的流体速度分布,继而影响叶轮的旋转稳定性;叶轮叶片压力面上靠近叶片前缘以及吸力面上靠近尾缘处存在压力突变区,易产生脱流现象;叶轮轮毂前后间隙区内流体受叶轮旋转影响而易产生漩涡流和明显的切向速度分量。     

Behavior of Isolated Disturbances Superimposed on Laminar Flow in a Rectangular Pipe

An investigation was conducted in a horizontal transparent rectangular pipe to study the behavior, in laminar flow, of an isolated turbulent-like disturbance produced by injecting a quantity of dye into the pipe 39 feet from the entrance. As the resulting mass of colored water moved downstream, time-distance measurements were made for the front of the dye mass and for the rear of the disturbance. The experimental setup, which is described in some detail, permitted reasonable control over the mean flow rate from which Reynolds number was calculated. The utilization of the data unfolded a functional relationship among three quantities: The ratio of the velocity of the rear of the disturbance to the velocity of the front of the dye U_R/U_F; the distance from the origin, X_F; and the Reynolds number R. The similarity of this work to that being done by Lindgren in Stockholm is mentioned.     

动量式气体流量计内部流场特性与测量性能研究

采用数值模拟与实验验证相结合的方法,得到了动量式气体流量计内部的流场,分析了流量变化时受力元件阻力系数的变化规律,研究了受力元件的形状、安装误差对测量性能的影响。研究结果表明,动量式流量计的阻力系数在量程范围内有较大变化,必须对阻力系数随雷诺数的关系式予以拟合;长方形受力元件阻力系数的拟合公式计算误差最小,拟合结果与实验数据的最大误差为0.32%,应优先选用;安装误差引起的阻力系数误差不大于0.32%,对测量精度影响较小,动量式流量计适合在线安装。     

Internal Flow of Acoustically Levitated Droplet

Under the microgravity environment, products of new and high quality materials solidified into homogeneous crystal by under cooling solidification have been the subject of much interest. Manufacture of material under the microgravity environment can be performed more static than that under the normal gravity. Handling technology of molten metal is important for such processes to hold in the limit space. However, when a large levitated droplet exists in the limit space, internal flow can be appeared remarkably. Elucidation of the effect of the internal flow of the levitated droplet is required in order to establish the containerless processing for new material under the microgravity environment. In current research, the internal flow of a levitated droplet was investigated by Zhao et al. (J Acoust Soc Am 106:589–595, 1999a and 106:3289–3295, 1999b) and Trinh et al. (Phys Fluids 12(2):249–251, 2000). These studies were analyzed numerically and theoretically. However, experimental study about the internal flow of the levitated droplet is not enough. According to our study Abe et al. (Microgravity Sci Technol 19(3–4):33–34, 2007), the authors observed internal flow of the water and glycerol droplet in normal gravity environment. In the water droplet, which is a low viscosity fluid, internal flow of both left and right hand rotation was observed. On the other hand, in the glycerol droplet, which is a high viscosity fluid, only rigid body rotation was observed. This research measured only two dimensional flows. It is thought that internal flow in the water is not two-dimensional but three-dimensional flow. Then, in order to investigate a three-dimensional flow structure in levitated water droplet in detail, we try to measure the three-dimensional flow in the levitated droplet. In the present study, test fluid with different viscosity is levitated. And, multidimensional PIV measurement is conducted to investigate the internal flow structure in a levitated droplet. Stereo images at equatorial plane of a levitated droplet are observed for measuring the three-dimensional component of velocity in the levitated droplet. As a result, the velocity of z direction is observed in the water droplet. On the other hand, the v _z is hardly observed in the glycerol droplet. The three dimensional structures of water and glycerol are differed. The difference of such flow structure is supposed to be due to the influence of the viscosity.     

螺旋风管内胀芯管连接工艺研究

通过大量试验、研究，确定了以开口、内胀、衬板及橡胶密封条为特点的螺旋风管内胀芯管连接工艺，经测试，其各项指标均高于国家标准及美国SMCANA标准的规定值。     

内文丘里管流量计及应用

本文介绍内文丘里管的工作原理、结构、技术性能及优缺点。内文丘里管(又称环形锥管),是新一代差压式流量测量仪表,是对传统文丘里管做了改型的异型文丘里管,它集经典文丘里管、环形孔板和耐磨孔板计量性能优点于一体,并且在能源计量工作中已取得良好的使用效果。     

可调式引射器流量调节特性研究

引射器在石油、化工、天然气输气过程、气波制冷、天然气脱水工艺、热能工程等领域中得到广泛应用.为了适应工况变化,需要研制流量可调式引射器.本文探讨了调节锥形状、尺寸对可调式引射器流量调节特性的影响.结果表明:对于圆锥型调节锥,随着锥角的增大,调节锥轴向可移动距离明显减小;流量与调节锥轴向移动距离呈二次曲线关系,即流量调节具有非线性性质.提出了一种可使引射器流量实现线性调节的调节锥型线方程.为具有良好调节性能的可调式引射器的研制打下基础.     

基于用户场景的交互设计流程研究

目的通过探析用户场景在交互设计中的应用,归纳出适用于互联网产品的基于用户场景的交互设计流程。方法分析用户场景的种类和构成元素,根据交互设计的概念,结合现有的交互设计流程,构建用户场景指导下的交互设计流程。结论在现有交互设计流程的基础上,提出了基于用户场景的交互设计流程及设计方法并建立模型,最后通过将该流程运用于互联网产品设计实例中,证明该理论方法的有效性与可行性。     

Study of Evaporative Convection in an Open Cavity under Shear Stress Flow

When a layer of volatile liquid is exposed to a shear flow of inert gas, thermal patterns, in the form of interfacial ripples and bulk plumes, are created by the combined action of evaporative, shear-driven and surface-tension-driven instabilities. The topology of the interfacial thermal patterns is mainly influenced by the geometry of the evaporating surface, the thickness of the evaporating layer, the intensity of the shear flow and by the physic-chemical properties of the working fluid. In this paper, by means of numerical simulations, we focused our attention on the dynamics of the interfacial thermal patterns for different working fluids and thicknesses of the volatile liquid layer. This study has been performed in the frame of the ESA sponsored Space Program on heat and mass transfer CIMEX-1. The choice of the fluids—ethyl alcohol and FC72 (n-perfluorohexane)—the reference values for the inert gas flow rate, the thickness of the liquid layer as well as the geometrical features of the computational domain correspond exactly to the ones foreseen for the CIMEX-1 experiment. However, the main conclusions can be considered of more general validity.     

水平内螺纹管内R410A流动凝结换热的实验研究

本文实验研究了R410A在水平内螺纹管内的流动凝结换热特性,分析了水力工况、测试管结构参数对管内制冷剂侧表面传热系数、压降的影响。结果表明:表面传热系数、压降均随着质量流速的增加、冷凝温度的降低而增大;虽然表面传热系数随着测试水Re的增加而减小,但测试水Re对压降的影响很小。利用单位压降表面传热系数对换热进行综合性能评价时发现,单位压降表面传热系数随着质量流速的增加而减小,随着冷凝温度的增大而增大。将实验数据与经典关联式的预测值进行对比,对于光滑管,除了Akers et al.关联式低估了实验数据,Shah关联式与Thome et al.关联式均高估了实验数据,并且Thome et al.关联式表现出最高的预测精度。而对于内螺纹强化管,Cavallini et al.关联式展现出最高的预测精度,而Koyama et al.关联式与Miyara et al.关联式均低估了实验数据。     

基于Fluent的气液两相流喷嘴内部流动特性仿真

目的探究气液两相流喷嘴内部流动特性及工作参数对流动特性的影响。方法测量得到气液两相流喷嘴的结构图,利用Fluent软件建立喷嘴模型,并选择流体体积(VOF)两相流模型和RNG(重整化群)k-?湍流模型,以常温状态下液态水和空气为研究介质,并以气压和液压为变量,进行多参数的流动特性分析,并引入气液比的概念。结果得到了不同时刻喷嘴内部的压力、速度及液相分布云图。其中最大压力为827 kPa,出现在出口段和进气段交叉的壁面上,由于喷嘴内部出现缩口,故出口段存在负压(?1.53 MPa);喷嘴内部最高速度出现在气液两相交汇处,为134 m/s;液相在最初迅速充满喷嘴后,逐渐与气相混合,最终出口段中心液相体积占比为0.543,混合情况良好。还得到了多参数对喷嘴内部压力、速度及液相分布的影响。结论使用软件仿真的方法得到了喷嘴内部的流动特性和多参数对流动特性的影响规律,并为进一步研究优化喷嘴结构及喷雾提供了建议和参考。     

Internal waves in an elliptical channel

Abstract

Internal waves in open channels of various depths are studied, in this paper, and a wetted cross section with an elliptical bottom is considered. The frequencies of the first three sloshing modes of internal waves in two superposed fluids contained in an elliptical channel are calculated for various ratios of the depths of the two layers. Numerical solutions converge to analytical solutions based on the shallow water theory as the depth of the thin lower layer approaches zero. Also, solutions for the frequencies of the longitudinal modes of progressive internal waves in two superposed fluid layers contained in an elliptical channel are calculated for various ratios of the depths of the two layers and for two different wave numbers k.     

Theoretical Study on the Interaction Between Constant-Pressure Specific Heat and Nonequilibrium Phase Change Process in Two-Phase Flow

In two-phase flow, the constant-pressure specific heat of a mixture correlates with the flow and the heat transfer processes. In this paper, the air-water-vapor system is taken as an example, and the behavior of the constant-pressure specific heat during a nonequilibrium phase change process in a two-phase flow system is deduced using the theory of two-phase flow and thermophysics; corresponding calculations are employed to the actual two-phase flow process. The results show that the flow and the phase change heat transfer processes determine the variation and magnitude of the specific heat. Vice versa, the specific heat affects the flow and the phase change heat transfer processes.     

基于心流理论的产品交互设计研究综述

目的 目前心流理论主要应用在教育教学及计算机等方面,在产品交互设计领域的研究还处于探索阶段,有必要分析心流理论的交互设计适用性,提出基于心流理论的产品交互设计方法。方法 通过文献研究法、归纳法,梳理心流理论的国内外研究进展,分析心流交互体验的实际验证方法,从产品角度提出心流理论在交互设计中的应用方式,对心流理论在产品交互设计中的启发性原理进行总结。结论 心流是一种积极情绪的体验,在适当情境下能够提升用户体验。通过建立清晰的用户目标、维系挑战与技能的提升、给予有效的操作反馈三个主要方面,对基于心流理论的产品交互设计方法进行拓展,丰富产品交互设计与心流理论相结合的理论空间,为产品交互设计方法研究提供参考。     

微柱群通道内饱和沸腾换热特性实验研究

为实现微小空间高效散热,本文以去离子水为工质,实验研究了工质流经高度和直径均为500μm的微圆柱组成的叉排微柱群通道时的饱和沸腾换热特性,并采用高速摄像机记录了通道内不同加热功率的气液两相流型,实验参数设定质量流速为341~598.3 kg/(m~2·s),热流密度为20~160 W/cm~2,蒸气干度为0~0.2。结果表明:随着热流密度增大,局部沸腾换热表面传热系数近似单调递减。在低干度区,局部沸腾换热表面传热系数随着质量流速的增加而增大,随着蒸气干度的增加而减小;受过冷沸腾气泡影响,工质进口温度越低,局部沸腾换热表面传热系数越大;随着热流密度增大,微柱群通道流动沸腾气泡流型依次为:泡状流、环状流,且泡状流区的局部沸腾换热表面传热系数明显高于环状流区。     

振动系统在不可测干扰作用下的主动控制研究

基于模态控制理论,利用优化特征值配置和稳定性理论等技术,提出阻尼性振动系统在不可测外扰作用下主动控制的一种设计方法,实验结果表明,对于低频振动系统,采用该方法设计控制系统可有效地降低系统的振幅,取得满意的控制效果。     

分流气体对冲消声器内流场及再生噪声分析

对新型分流气体对冲排气消声结构进行了内流场分析,发现隔板以及弯头部件区域存在压力损失较大的问题,通过增加导流环,加大弯头半径等方法,减小了消声单元的排气压力损失,并利用FW-H声学比拟法对改进前后的消声器进行了再生噪声分析。结果表明,通过对消声器内部结构的合理改进,在入口流速为40m/s时,改进后的消声器压力损失降低了35%,出口噪声降低了1.5dB左右。并通过试验验证了数值计算的正确性,研究结果对新型消声器的设计具有一定的指导意义。