卧式旋转圆筒粘度计的测试原理

卧式旋转圆筒粘度计是一种新型的粘度计。它不同于常见的直立式旋转圆筒粘度计,在结构、测试原理、测试方法等方面都有它自己的特点。本文简单地介绍了卧式旋转圆筒粘度计的结构;从牛顿内摩擦定律出发,讨论了流体在旋转圆筒间的动平衡流动;讨论了它的流速表达式、粘度表达式、流变方程;简要地介绍了宾汉流体和幂律流体的相应表达式;最后简述了这种粘度计的优点。     

自由旋转粘度计的研究与设计

给出一种借助单片机与FPGA/CPLD技术的自由旋转粘度计设方方法.自由旋转粘度计首先将流体粘度转换成转子的角位移信号,然后通过编码盘将角位移转移为测量脉冲,其后采用FPGA精确测量其脉冲参数,最终获取粘度测量结果.详细介绍了自由旋转粘度计的基本结构与工作原理,并对测量误差进行了简单分析,同时介绍了基于FPGA技术进行角位移测量的详细设计方法.该粘度计可以在很低的转速、很短的时间测得流体的粘度,这对于提高测量精度是非常有效的.     

非牛顿流体流变学特性测试系统

介绍了一种用于精密测量非牛顿流体流变学特性的测试系统.该系统解决了非牛顿流体从高剪切到低剪切全程扫描测量问题,可对流体的粘性定律和运动规律进行描述和实验分析.     

旋转圆筒泄漏流模型研究

为获得叶轮机叶尖泄漏流动规律,对周向压差作用下同轴旋转圆筒间泄漏流进行研究。以二维周向压差同轴旋转圆筒为模型,求解流动控制方程组获得以转速比和半径比量纲一化函数表达的圆筒间周向流动速度解析解;导出考虑周向压力梯度和圆筒旋转共同作用引起的周向量纲一泄漏流流量解析表达式;获得内外圆筒转速比、半径比、流体介质和流体温度等因素对泄漏流量的影响规律。结果表明:旋转圆筒间泄漏流量随转速比增加而增加,随半径比增加而减少;介质黏性较小时旋转圆筒的转动对泄漏流量的影响较小,周向压力梯度对泄漏流量的影响较大;介质黏性较大时周向压力梯度对泄漏流量的影响较小,圆筒的转动对泄漏流量的影响较大。     

可调压可视化微间隙Couette流变仪的研究及应用

采用精密的机械加工和独特的气动旋转密封技术,研制出可调压可视化微间隙Couette流变仪。外圆筒旋转内圆筒静止的特点,使该流变仪能产生剪切速率高达105/s数量级稳定的纯剪切流。利用商业旋转流变仪,测量试验用中、低粘度硅油在低剪切速率和不同温度下的粘度,应用粘温关系,推算出高剪切速率下粘性热使粘度下降的量,其值与微间隙Couette流变仪的测量结果较为吻合。在一定的切应力下,观察到淡水和中低粘度硅油在微间隙中发生剪切空化的现象,发现剪切空化的发生还强烈依赖于流体中气体的相对溶解量。     

加压管式流变测试系统的设计

非牛顿流体流变特性复杂多样,测试原理有管流法、落球法、圆盘法、同轴旋转粘度计法等,相应的测试仪器也是多种多样.但针对同一种流动特性较差的非牛顿流体,若采用不同的方法和仪器进行测试,由于不同的测试状态被测流体的受力和运动状态不同,得出的流变特性及参数也是不同的.尤其是针对l丁业管道输送的流动性较差、流变特性又较难测试的非牛顿流体,如何准确测试被输送介质的流变特性,为管道工艺提供设计依据是亟待解决的问题.基于此,本文设计了加压管式流变测试系统,基于管流法的流变测试原理,通过氮气加压致使被测试物料流动,模拟管道输送的工况,测试流动性较差的非牛顿流体的流变特性,为管道工艺设计提供实验平台.     

一种新型Couette流变仪的力矩修正和粘度测量误差分析

为准确计算得出新型Couette流变仪工作段剪切力矩,通过对计算机采集的电机输出转矩进行校核,得出了电机输出转矩真实值;利用商业旋转流变仪测量,得出了实验流体标准大气压下的粘温关系,最后得出了修正力矩与雷诺数的关系。考虑到该流变仪在制造和数据采集中存在误差,利用误差传递计算方法得出了新型Couette流变仪在测量流体粘度时的误差范围。分析结果为进一步测量不同状态下流体的粘度和研究空化奠定了基础。     

CCD像面旋转引起的脱靶量误差及检测方法

分析了光电测量设备电视系统的CCD传感器像面旋转这个普遍存在的问题所带来的脱靶量测量误差,建立了一些相关的数学模型,并且讨论了在不同像面旋转角情况下的误差变化规律.简要地介绍了这种测量误差的检测方法以及修正方法.实际检验表明,上述方法不仅能很好地修正CCD传感器像面旋转所引起的脱靶量测量误差,显著提高电视系统脱靶量测量精度,而且对于红外电视测量系统也是同样适用的.     

布拉本达通用流变仪的调试与标定

布拉本达通用流变仪Brabencler Rheotron是一典型的旋转流变仪用从测定牛顿型或非牛顿型流体的切应力、剪切粘度和第一法向力差以及振荡剪切响应等流变参数。本文根据该仪器的结构特征和流变测量学的基本原理,就速度校正、温度控制、转矩和法向力线性响应以及其他测量元件技术特性的鉴定提出校核与调整的方法;并且归纳出标定仪器常数的计算方法,以及适宜于该仪器的求取假塑性流体剪切流变参数的非牛顿校正方法。这些结果对于其他类型的旋转流变仪或粘度计的校正与标定也具有参考价值。     

锂基润滑脂屈服应力测定方法的探讨

选用旋转流变仪测定了锂基润滑脂的屈服应力。根据锂基润滑脂的流变性质,采用稳态、瞬态和动态实验等方法测定了屈服应力值。实验结果表明,不同测定方法对屈服应力值的影响较大,稳态、瞬态和动态实验测得的屈服应力值依次逐渐增大;稳态和动态实验的测定值为确定的值,而瞬态实验得到的应力值为一个范围。     

Design and use of an online drilling fluid pipe viscometer

The accurate and frequent measurement of the drilling fluid's rheological properties is essential for drilling engineering. To measure drilling fluid's rheological properties automatically and frequently, we design an online pipe viscometer. First, we introduce the measurement principle, calculation flow chart, and design scheme. The pulsation damper and back pressure valve are used to stabilize flowrate and pressure which can improve the accuracy of the pipe viscometer. Then the errors under various static hole sizes are measured, and the static hole with the smallest error is selected as the measurement pipe of the pipe viscometer. Finally, various drilling fluids are tested. Compared with the standard six-speed viscometer, the shear stress error of the six standard shear rates (1022, 511, 340, 170, 10, 5s⁻¹) is within 1Pa. The designed pipe viscometer can frequently measure drilling fluid's rheological properties and meets the needs of on-site online testing.     

部分凝固Sn-Pb共晶合金的显微组织和流变性

用可液淬取样的同轴双筒粘度仪,研究了Sn-Pb共晶合金在切变流动中的凝固组织和流变性质。结果表明：切变凝固的共晶组织是由粒状组织单元构成的,单元内有三种不同形态的共晶区域。凝固中的合金浆粒具有非牛顿流体的流动性质。     

Blood viscosity measurements using a pressure-scanning capillary viscometer

A previously designed capillary viscometer with measuring differential pressure was modified to measure the viscosity of non-Newtonian fluids including unadulterated blood continuously over numerous shear rates in a single measurement. Because of unavoidable experimental noise and a limited number of data, the previous capillary viscometer experienced an inaccuracy and could not directly determine a viscosity without an iterative calculation. However, in the present measurement there are numerous data available near the point of interest so that the numeric-value of the derivative,d(lnQ)/dln τω), is no longer sensitive to the method of differentiation. In addition, relatively low and wide shear rate viscosity measurements were possible because of the present precision pressure-scanning method with respect to time. For aqueous polymer solutions, excellent agreement was found between the results from the pressure-scanning capillary viscometer and those from a commercially available rotating viscometer. In addition, the pressure-scanning capillary viscometer measured the viscosity of unadulterated whole blood without adding any anticoagulants.     

边界滑移对柱塞偶件间油膜流动规律的影响

斜盘式轴向柱塞泵内柱塞偶件间油膜为相对运动的偶件提供润滑及密封作用。油膜流动将直接影响柱塞偶件的工作性能。深入分析偶件间油膜的流动规律对设计与优化柱塞偶件有重要意义。基于Navier-Stokes（N-S）方程,引入Navier边界滑移推导偶件间油膜流动方程,根据柱塞运动的周期性规律,分析单个周期内滑移长度和柱塞泵转速对油膜流动剪应力及流量的影响。研究发现：吸油阶段时近柱塞壁面处油膜剪应力随滑移长度增大而减小,流量随着滑移长度增大而增大,柱塞运动速度最大且滑移长度由1 μm增大到3 μm后,剪应力减小18%,流量增大13.59%;排油阶段柱塞运动速度越大,近柱塞壁面处剪应力和油膜流量与无滑移条件下的差距越小。在滑移长度为1 μm的条件下柱塞泵转速由1 500 r/min增大到4 000 r/min时,近柱塞壁面处的油膜剪应力与无滑移条件下相比降低明显,一个周期内油膜总流量与无滑移条件下相比差距减小。     

磁流变胶泥流变学特性测试装置研究

现有的商用磁流变仪不能满足磁流变胶泥高剪切率和高剪切应力测试的要求,对比设计了密闭圆筒剪切模式的磁流变胶泥流变特性测试装置。在完成总体结构设计的基础上,建立了剪切通道励磁磁路的分析模型,得出了剪切通道磁场强度与励磁电流的关系,并进行了有限元仿真验证。考虑转子与外筒存在倾斜,建立了磁流变胶泥转矩传递的力学模型,得到了转子与外筒倾斜角度与传递转矩误差的理论关系。完成了测量装置样机的制作,开展了磁流变胶泥流变学特性测试,在低剪切率下测量装置测试结果与安东帕流变仪测试结果能较好吻合。研究表明,测试装置能够实现25 000 s-1的高剪切率和200 k Pa的高剪切应力测试。     

The High-Pressure Rheology of a Soap-Thickened Grease

The high-pressure rheology of a soap-thickened grease and the base oil has been characterized using a falling-body viscometer, high-pressure Couette viscometer, and a high-pressure penetrometer. At shear stress from 0.1 to 1 MPa, the response of the grease was approximately linear with rate of shear with a viscosity about twice that of the base oil. Apparent yield stress behavior is observed at lower shear stress. A new modified Bingham model is offered to describe the experimental observations. These results are relevant for simulations of elastohydrodynamic lubrication and journal bearings operating at elevated ambient pressure.     

悬臂梁腹板裂纹的分析和处理

对宁波港56t铁矿石桥式抓斗卸船机悬臂梁腹板产生的大范围剪切裂纹的原因作了分析，认为在接触剪应力和弯曲剪应力共同作用下产生主裂纹，二次裂纹则是由弯曲法应力和垂直剪应力引起的。并对该裂纹进行焊接修理。其对桥架型港口起重机的金属结构设计、使用管理具有参考和借鉴意义。     

Comparison of DNS and Reynolds stress modelling of flow around a rotating cylinder

The low Reynolds number stress-omega model is applied to flow associated with a rotating cylinder operating in a larger, stationary cylinder. The working fluid fills the gap between the cylinders. Direct numerical simulation data are used to test the predictions by this turbulence model. Previous work has shown that simpler models are unable to predict with reasonable accuracy the wall shear stress experienced by the rotating cylinder. The present study with a more complex turbulence model shows that the wall shear stress on the rotating cylinder is underestimated significantly. Examination of turbulence velocity fluctuation intensity distributions points to underprediction of the streamwise turbulence level and excessive values of the wall normal turbulence level. Results are given for no shear and a wall shear at the outer cylinder surface but no effect on the inner cylinder statistics was found. An examination of the Reynolds stress anisotropy tensor components highlights a significant deficiency in this parameter which is an essential component of the pressure-strain modelling of Reynolds stress models. The most significant aspect is a rapid decrease of the streamwise component of the Reynolds stress anisotropy tensor relative to the direct numerical simulation results and values which are too low for the other two components.     

Continuous viscosity measurement of non-Newtonian fluids over a range of shear rates using a mass-detecting capillary viscometer

A newly designed mass-detecting capillary viscometer uses a novel concept to continuously measure non-Newtonian fluids viscosity over a range of shear rates. A single measurement of liquid-mass variation with time replaces the flow rate and pressure drop measurements that are usually required by capillary tube viscometers. Using a load cell and a capillary, we measured change in the mass flow rate through a capillary tube with respect to the time,m(t), from which viscosity and shear rate were mathematically calculated. For aqueous polymer solutions, excellent agreement was found between the results from the mass-detecting capillary viscometer and those from a commercially available rotating viscometer. This new method overcomes the drawbacks of conventional capillary viscometers meassuring non-Newtonian fluid viscosity. First, the mass-detecting capillary viscometer can accurately and consistently measure non-Newtonian viscosity over a wide range of shear rate extending as low as 1 s⁻¹. Second, this design provides simplicity (i. e., ease of operation, no moving parts), and low cost.     

电流变液力学特性的实验研究

电流变液的力学性能参数是评价电流变液的性能指标之一 ,也是含电流变液智能结构建模所需的基本参数。对电流变液这种新兴的材料 ,其力学参数测试尚没有成熟统一的方法。本文研制了一系列电流变液力学参数专用测试仪器 ,并对所研制的电流变液的基本力学参数进行了系统的测试。结果表明 ,电流变液的拉伸模量和剪切模在屈服转捩前后有明显差异。本文所研制的电流变液在应力应变曲线上无过冲现象 ,其强度满足一定条件下的工程应用要求