一种直接驱动式振动管密度计研究

为解决常用的U型管密度测量方法中存在的弊端,该文研制一套基于振动管原理的密度测量系统,该系统以通过振动管的交变电流实现振动激励,克服传统的振动管密度计振动管重心发生偏移的弊端。该系统由密度测量装置、恒温系统、压力系统以及数据测量系统组成。实验使用纯水和无水乙醇标定该装置在温度范围303.15～323.15 K、压力范围0.1～20 MPa的仪器常数。测量异丁醇在相应温度与压力范围内的密度,并与文献数据进行比较,验证装置的可行性。所得结果可以为其他研究人员提供参考。     

支撑共振法测量液体密度的研究

采用支撑共振法测量材料杨氏模量的实验装置,由分离变量法近似求解内部含液体管状材料横振动Housner方程,得到管状材料内部液体密度计算公式。通过实验测量并计算了蒸馏水及不同浓度蔗糖溶液的密度值,得到的实验值与理论值之间的相对误差在正常误差范围3%以内。     

燃煤流化床床料的密度、错位密度和颗粒形貌研究

在两种燃煤颗粒和一种循环流化床锅炉冷渣颗粒形貌测量的基础上,提出了颗粒错位密度的概念,建立了颗粒外接六面体体积充满度与错位密度之间的关系。测量结果显示,采用错位密度处理颗粒形貌数据时,原本分散的测量数据表现出明显的线性化效果。对于实验中的两种煤,将颗粒密度当作常数处理对错位密度几乎没有影响。而对于循环流化床锅炉的冷渣,将颗粒密度当作常数,造成较大偏差。     

(近)共晶铝合金密度的测量与计算

结合各种数据对8个铝基共晶合金和5个铝基合金在20℃时的点阵常数进行了估算,以此计算出了合金的密度.点阵常数的估算是通过加和各种合金元素对铝的点阵常数的影响得出的.这种方法计算出的结果与流体静力学法室温密度测量的结果相比,误差在1%以内.     

在线振动管液体密度计检定装置的研究

密度量值作为原油和成品油计量交接领域的关键性参数,在现代原油与成品油交接中需要时时精确的测量油品密度,以便实现体积量与质量之间的准确转换。新疆地处石油高产区,石油石化领域液体振动管密度计使用范围广、数量大。为解决新疆乃至西北地区液体振动管密度计溯源问题,新疆计量院开展了液体振动管密度计检定装置的研究工作,该装置由恒温控制实验室、制度化控温槽、高温高压数字标准密度计、旋转式恒温箱组成。一等密度计作为标准器,高温高压数字密度计作为副标准参与振动管密度计的量值传递。装置温度范围10～60℃,密度范围650～1400kg/m3,标准装置的稳定性优于0. 15%。     

圆筒谐振式液体密度传感器的结构设计

简要介绍了圆筒谐振式液体密度传感器的测量原理与系统结构,分析了在结构设计上应该特别注意的几个问题,提出了一种新的圆筒谐振式液体密度传感器的振动筒设计方法。试验数据表明,该传感器的测量精度有了很大提高,具有很高的现实意义和使用价值。     

我国首次参加振动样品磁强计磁性测量国际比对

国际电工委员会磁合金与磁钢分委员会(IEC TC68)于近期举行了振动样品磁强计磁性测量国际比对,比对针对永磁铁氧体球和磁性薄膜两种磁性材料的主要磁特性进行循环测量.比对结果表明当前国际范围内使用振动样品磁强计测量磁性材料具备较为良好的复现性,永磁铁氧体球的磁性测量偏差典型范围在2％以内,磁性薄膜的磁性测量偏差典型范围在2.5％以内,这一结果有力地支持振动样品磁强计发展成为一种IEC标准方法.中国计量科学研究院代表我国参加了此次比对,其比对结果位于此次比对的典型偏差范围之内.     

声管脉冲回波法吸声系数测量技术

利用可控脉冲声信号,采用回波方法,在圆形声管中测量了样本材料的吸声系数.依据回波信号和入射声波的功率谱密度先解算反射系数,然后计算吸声系数.与B&K 4206阻抗管测量结果相比,在200 Hz～5 kHz频段内吸声系数差别在10%以内.所用脉冲声具有波形规则、脉冲时间短、频带宽的特点,测量精度比同类方法显著提高,特别是低频区域数据可靠.测量系统装置简单、重复性好.测量装置的不确定度主要源于样品在声管中安装的精密性.     

一种基于光子多普勒原理的高温振动测量方法探究

针对重大装备研制试验中面临的高温振动测量问题,建立了一套基于光子多普勒原理的全光纤高温振动测量装置。在0～1200℃温度范围内开展了振动测量性能测试,试验结果表明该装置实现了最大振动速度1m/s和最大振动加速度378.4 m/s2的测量,速度灵敏度的幅值线性度小于0.5%,频率响应范围为0～2 kHz,具有很好的稳定性与可靠性,且在800℃以上高温振动测量时表现出对被测面反光率要求较低的优势,为应用于航空航天等领域的高温振动测量设备研制提高了重要参考。     

我国仿真乳突的比对测量(英文)

本文叙述了1986年9月进行的9台仿真乳突的比对测量。结果表明,测量数据与出厂数据间的力灵敏度偏差均小于±1dB,机械阻抗值均在IEC-373(1983)所给的容限以内,证实了我国骨导听力计量标准装置是稳定可靠的。     

PρT Measurements of Nonafluorobutyl Methyl Ether and Nonafluorobutyl Ethyl Ether Between 283.15 and 323.15 K at Pressures Up to 40 MPa

In this paper, experimental densities for nonafluorobutyl methyl ether and nonafluorobutyl ethyl ether from 283.15 to 323.15 K at pressures up to 40 MPa are reported. The density measurements were performed by means of a high pressure vibrating tube densimeter. Data reliability was checked by comparing experimental results obtained for tetrachloromethane—whose density is close to those of the fluids studied—with recommended literature data. Furthermore, the isobaric thermal expansion, isothermal compressibility, and internal pressure have been calculated from these density data.     

An Automated Vibrating-Tube Densimeter for Measurements of Small Density Differences in Dilute Aqueous Solutions

The core of the automated apparatus is a high-temperature high-pressure densimeter with a metal vibrating tube designed for accurate flow measurements of densities of liquids in the temperature range from 298 to 573 K and at pressures from 0.1 MPa up to 30 MPa. The densimeter is being employed for a study of dilute solutions of aqueous solutions of organic substances where the density difference {solution–water} is a primary experimental quantity. Consequently, partial molar volumes of solutes at infinite dilution in water are evaluated from the measured data. Two sampling sections are connected in series in the filling line of the densimeter. One of them is employed for manual filling of the measured sample into a sampling loop using a syringe. The other section allows fully automated measurement of up to 12 samples in one run. The recorded data are evaluated after the automated run is completed.     

The Viscosity and Density of <Emphasis Type="Italic">n</Emphasis>-Dodecane and <Emphasis Type="Italic">n</Emphasis>-Octadecane at Pressures up to 200 MPa and Temperatures up to 473 K

A vibrating-wire instrument for simultaneous measurement of the density and viscosity of liquids under conditions of high pressure is described. The instrument is capable of operation at temperatures between 298.15 and 473.15 K at pressures up to 200 MPa. Calibration was performed by means of measurements in vacuum, air, and toluene at 298.15 K. For n-dodecane measurements were made along eight isotherms between 298.15 and 473.15 K at pressures up to 200 MPa while for n-octadecane measurements were measured along seven isotherms between 323.15 and 473.15 K at pressures up to 90 MPa. The estimated uncertainty of the results is 2% in viscosity and 0.2% in density. Comparisons with literature data are presented.     

Compressed Liquid Densities of 1-Pentanol and 2-Pentanol from 313 to 363 K at Pressures to 25 MPa

Compressed liquid densities of 1-pentanol and 2-pentanol have been measured from 313 to 363 K at pressures to 25 MPa. Measurements have been achieved using a vibrating tube densimeter. Water and nitrogen are the reference fluids to calibrate the densimeter. Measurements uncertainties are estimated to be ±0.03 K for temperatures, ±0.008 MPa for pressures and ±0.20 kg·m⁻³ for densities. Two volume-explicit equations with five and six parameters and the 11-parameter BWRS equation of state are used to correlate the experimental densities of 1-pentanol and 2-pentanol reported in this work. Statistical values for the evaluation of the correlations are reported. Comparisons with literature data are performed for the temperature and pressure ranges of the measurements.     

高精度单浮子磁悬浮密度测量系统研制

研制了一套高精度的流体压力-密度-温度(p,ρ,T)测量系统,其适用温度、压力和密度范围分别为90—290 K,0—3 MPa,0—2 000 kg/m3。该系统基于阿基米德原理,采用单浮子磁选耦合力传递方法,实现密度的高精度测量。该系统的温度、压力测量标准不确定度分别为5 mK、250 Pa(1.5 MPa量程)/390 Pa(3 MPa量程),密度测量最大相对标准不确定度为0.1%。用新研制的密度测量系统,对190—276 K温度区间和0—3 MPa压力区间的甲烷气体密度进行了测量,实验结果与REFPROP密度值有较好的一致性,验证了该系统的可靠性。     

Thermophysical Properties of 1,1,1,3,3-Pentafluorobutane (R365mfc)

This paper presents an experimental study on various thermophysical properties of a new fluoroalkane, 1,1,1,3,3-pentafluorobutane (R365mfc). The thermal conductivity of R365mfc was measured in the liquid phase near saturation conditions at temperatures between 263 and 333 K using a parallel plate instrument with an uncertainty of less than ±5%. For the measurement of the saturated liquid density between 273 and 353 K, a vibrating tube instrument was used. The uncertainty of the density measurements is less than ±0.1%. In addition, experimental data have been obtained for R365mfc under saturation conditions over a wide temperature range from about 253 to 460 K using light scattering techniques. Light scattering from the bulk fluid has been applied for measuring both the thermal diffusivity and the sound speed in the liquid and vapor phases. Light scattering by surface waves on a horizontal liquid–vapor interface has been used for the simultaneous determination of the surface tension and kinematic viscosity of the liquid phase. With the light scattering techniques, uncertainties of less than ±1.0, ±0.5, ±1.0, and ±1.2% have been achieved for the thermal diffusivity, the sound speed, the kinematic viscosity, and the surface tension, respectively.     

High-Pressure Measurements of the Viscosity and Density of Two Polyethers and Two Dialkyl Carbonates

The viscosity and density of four pure liquid compounds (dimethyl carbonate, diethyl carbonate, triethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether) were measured at several temperatures between 283.15 and 353.15 K. The density measurements were performed up to 60 MPa with an uncertainty of 1×10^–4g·cm^–3. The viscosity at atmospheric pressure was measured with an Ubbelohde-type glass capillary tube viscometer with an uncertainty of ±1%. At pressures up to 100 MPa the viscosity was determined with a falling ball viscometer with an uncertainty of ±2%. The density (410 experimental values) and viscosity data (184 experimental values) were fitted to several correlation equations.     

A Vibrating Plate Fabricated by the Methods of Microelectromechanical Systems (MEMS) for the Simultaneous Measurement of Density and Viscosity: Results for Argon at Temperatures Between 323 and 423K at Pressures up to 68 MPa

In the petroleum industry, measurements of the density and viscosity of petroleum reservoir fluids are required to determine the value of the produced fluid and the production strategy. Measurements of the density and viscosity of petroleum fluids require a transducer that can operate at reservoir conditions, and results with an uncertainty of about ±1% in density and ±10% in viscosity are needed to guide value and exploitation calculations with sufficient rigor. Necessarily, these specifications place robustness as a superior priority to accuracy for the design. A vibrating plate, with dimensions of the order of 1 mm and a mass of about 0.12 mg, clamped along one edge, has been fabricated, with the methods of Microelectromechanical (MEMS) technology, to provide measurements of both density and viscosity of fluids in which it is immersed. The resonance frequency (at pressure p = 0 is about 12 kHz) and quality factor (at p = 0 is about 2800) of the first order bending (flexural) mode of the plate are combined with semi-empirical working equations, coefficients obtained by calibration, and the mechanical properties of the plate to provide the density and viscosity of the fluid into which it is immersed. When the device was surrounded by argon at temperatures between 348 and 423 K and at pressures between 20 and 68 MPa, the density and viscosity were determined with an expanded (k = 2) uncertainty, including the calibration, of about ±0.35% and ±3%, respectively. These results, when compared with accepted correlations for argon reported in the literature, were found to lie within ±0.8% for density and less than ±5% for viscosity of literature values, which are within a reasonable multiple of the relative combined expanded (k = 2) uncertainty.     

Pressure and Temperature Dependence of the Speed of Sound and Related Properties in Normal Octadecane and Nonadecane

The speed of sound was mesured in liquid n-octadecane and n-nonadecane using a pulse technique operating at 3 MHz. The measurements were carried out at pressures up to 150 MPa in the temperature range from 313 to 383 K. The experimental results combined with atmospheric density measurements were then used to evaluate volumetric properties such as the density and the isentropic and isothermal compressibilities up to 150 MPa in the same range of temperature. The density data were fitted with a six-parameter modified Tait equation within the experimental uncertainty.     

A vibrating-wire densimeter for liquids at high pressures: The density of 2,2,4-trimethylpentane from 298.15 to 348.15 K and up to 100 MPa

A new apparatus for the measurement of liquid densities at high pressures is presented. The instrument is a development of a vibrating-wire densimeter described earlier and uses the buoyancy force exerted by the sample fluid on an immersed buoy to alter the tension of a wire from which it is suspended. The tension of the wire is related to its resonant frequency under steady-state transverse vibrations through a rigorous theoretical model which includes a complete analysis of the hydrodynamic effect of the fluid surrounding the wire. The present instrument uses a new design for the measuring cell with the purpose of relieving the degeneracy of perpendicular oscillation modes of the vibrating wire. The modifications lead to a significant increase in the precision of the results. Tests performed on the new apparatus and the operating procedure used, which requires the determination of one cell parameter from one density datum at atmospheric pressure, are described. New results for the density of liquid 2,2,4-trimethylpentane at temperatures from 298.15 to 348.15 K and pressures up to 100 MPa are presented. The data obtained have a precision of ±0.05% at a 2a level and an estimated accuracy of approximately ±0.1%.