浮子流量传感器粘度影响的研究

通过研究粘度对浮子流量传感器测量的影响,运用实验手段,测出粘度为10~50mm2/s的4050航空润滑油对浮子流量传感器的影响误差约为10%左右。结合浮子流量传感器的边界层理论与内部流体流动情况,运用CFD软件仿真,将粘度对DN40mm浮子流量传感器影响误差控制在5%以内。从流场的角度分析浮子流量传感器粘度影响规律及其机理,并且模式化仿真模型,为以后流量传感器的仿真提供了借鉴作用。     

气体浮子流量计测量误差的实验研究

在水流量标准装置上刻度气体浮子流量计后,分别在水流量标准装置和气体流量标准装置上研究了其测量误差。实验研究发现,在水装置上检定的气体浮子流量计测量空气流量时测量值大于真实值,其原因为:检定介质的动力粘度大于被测介质的动力粘度。故为了保证浮子流量计的精度等级,在水装置上检定气体浮子流量计时,必须考虑流体粘度的影响,在刻度换算公式中引入粘性系数k。     

浮子流量计压力损失的实验研究

在相同流动条件下,对不同口径、不同流量范围的锥管浮子流量计和孔板浮子流量计的压力损失进行了实验研究。实验研究发现,浮子流量计的压力损失并非定值,而是随流量的增大而增大;和锥管浮子流量计相比,相同口径的孔板浮子流量计的压力损失更大。考虑流体粘性后,分析了浮子流量计实际压力损失的构成,并以100 mm口径的锥管浮子流量计和孔板浮子流量计为例,对其压力损失进行了估算。     

水平式安装金属管浮子流量计的仿真与实验研究

通过对适合安装于水平管道的特殊结构的金属管浮子流量计三维湍流流场的数值仿真及实验研究提出一种基于计算流体力学的流量传感器设计方法。流场仿真所需的模型采用GAMBIT来建立,通过FLUNT软件进行仿真,仿真过程中利用受力平衡控制计算精度。数值仿真结果和实验结果比较当浮子受力平衡度误差为9. 5%时,流量误差为0. 944%,证实了仿真结果的准确性,同时利用流场仿真信息对流量传感器模型做了进一步的优化。     

[bmim][BF_4]、[bmim][PF_6]离子液体及其与DMF二元体系在293.15～338.15K下的粘度

为获得离子液体与有机物物理性质的数据,常压下,293.15～338.15 K温度范围内,分别测定了1-丁基-3-甲基咪唑四氟硼酸盐（[bmim][BF4]）、1-丁基-3-甲基咪唑六氟磷酸盐（[bmim][PF6]）2种咪唑类离子液体以及它们和N,N-二甲基甲酰胺（DMF）构成的2个二元体系的粘度,采用Vogel-Tamman-Fulcher（VFT）方程和Arrhenius-like方程对所测粘度数据进行关联。结果表明,同一温度下,3种纯溶液粘度大小顺序依次为：DMF〈[bmim][BF4]〈[bmim][PF6]。[bmim][BF4]、[bmim][PF6]离子液体及其与DMF构成的二元体系的粘度均随着温度的升高和DMF摩尔分率的增加而降低。实验条件下,DMF＋[bmim][BF4]和DMF＋[bmim][PF6]二元体系的粘度变化范围分别为1.26～125.5 MPa·s和1.11～165.7 MPa·s。VFT方程对于DMF-[bmim][BF4]与DMF-[bmim][PF6]体系的关联结果比Arrhenius-like方程较好,其总平均绝对误差、总平均相对误差、以及总平均标准方差分别为0.561 9 MPa·s和0.918 6 MPa·s、0.026 8 MPa·s和0.020 9 MPa·s、0.725 5 MPa·s和1.125 1 MPa·s。     

可拆式流量变送器介质粘度补偿模型试验的研究

本文将LW型传统可拆式流量变送器作为研究对象,对其进行了广泛的理论和实验研究,得到了这种流量传感器的介质粘度补偿模型,与此同时,我们还应用了具有粘度自动补偿功能的可拆式流量变送器积算显示仪表,这样传统可拆式流量变送器运用相应粘度补偿模型,并配以相应的计算显示仪表,可以实现对粘性液体的流量测量。     

高含水率中药渣的带式压滤机压滤脱水试验

分析中药渣中的水分,阐述中药渣受挤压作用时的脱水机理,结合中药渣的特性和带式压滤机的脱水工艺,对压滤机的布料器进行改造,增加两级分料螺旋,改善压滤效果,使其适用于中药渣脱水试验,增加物料处理量,减少溢料现象,降低污水含固率,减少运行人员劳动强度。采用控制变量法,试验研究压滤机的不同脱水段、压力、带速、中药渣初始含水率等4个因素对脱水效果的影响,结果表明：物料初始含水率越大,不同脱水段的脱水率越大,滤饼的含水率越大;Ⅰ级脱水辊对物料脱水效果影响最大,楔形预压段对物料脱水效果影响最小;中药渣的初始含水率不宜超过80.16%;Ⅰ级脱水辊压力选择0.2～0.6MPa较合适;带速在0.3～0.5m/s范围内时,滤饼的含水率在65%～ 66%之间,脱水效果较好。     

同向旋转双螺杆挤出机计量段中聚合物挤出的模拟

建立了非牛顿粘性聚合物熔体在同向旋转双螺杆挤出机计量段中的三维 非等温流动模型,利用网络叠合技术分析挤出机计量段内速度、温度、压力、粘度、粘性耗散热的分布以及螺杆转速、轴向压差对挤出量的影响。     

一种RTM用耐烧蚀改性酚醛树脂性能研究

对一种新型改性酚醛树脂的粘度特性、耐热性和耐烧蚀性能及其复合材料的性能进行了研究,得出该树脂体系的粘度在60~120℃的范围内均小于800m Pa·s,且在70℃、80℃时工艺适用期大于150min;其玻璃化温度Tg为253℃,氮气气氛800℃残炭率可达到67.1%,质量烧蚀率和线烧蚀率分别为0.0766g/s、0.119mm/s;RTM成型碳纤维增强改性酚醛树脂复合材料的层间剪切强度和轴向压缩强度分别可达39.3MPa和177MPa,氧-乙炔烧蚀的线烧蚀率和质量烧蚀率分别为0.044mm/s、0.0762g/s。结果表明,该种树脂体系具有粘度低、工艺适用期长以及良好的耐热性和耐烧蚀性能,能很好地满足RTM工艺的要求,且其碳纤维针刺复合材料具有作为耐烧蚀材料的潜质。     

浮子流量计流量方程的原理分析与修正

为获得正确的浮子流量计流量方程,对现有习用浮子流量计流量方程在理论推导过程中存在的问题进行讨论,针对习用流量方程中物理概念混淆、忽略浮子高度和选用非典型浮子模型的问题进行了修正,推导出新浮子流量计流量方程:Q=αAR2g特征曲线。新浮子流量计流量方程相对于原有流量方程能够更合理的描述浮子流量计的工作机理。     

Prediction of lower/upper limiting viscosities

An analysis based on steady uniform laminar flow of a non-Newtonian fluid in a tube is presented which predicts Newtonian flow behaviour in the limits of zero and infinite shear, respectively. It is shown that an upper limiting viscosity occurs in the limit of infinite shear for a fluid with or without a yield stress, whereas a lower limiting viscosity is obtained for a fluid without a yield stress in the limit of zero shear. For a fluid with a yield stress, an infinite viscosity is found in the limit as the shear stress approaches the yield stress.     

Predictive models for the viscosities of multicomponent liquid n‐Alkane and regular solutions

The pseudo‐binary model developed by Wu and Asfour (1992) has been used to modify some existing viscosity predictive models to that they can predict the viscosities of multicomponent liquid n‐alkane and regular mixtures. The McAllister three‐body interaction model and the Grunberg‐Nissan viscosity equation were both employed, after modification, to successfully predict the viscosity of multicomponent liquid n‐alkane and regular solutions. The modified Generalized Corresponding States Principel (MGCSP) reported by Wu and Asfour (1992), for only predicting the viscosities of n‐alkane mixtures, has been extended to predit the viscosities of multicomponent regular solutions. The predictive capabilities of several predictive models were analyzed. The obtained results showed that the pseudo‐binary McAllister model predicts the viscosity data better than the other existing predictive models.     

Mixing rules for predicting the viscosity of bitumens saturated with pure gases

Mixing rules are developed and evaluated for predicting the viscosity of Alberta bitumens saturated with each of N₂, CO, CH₄, CO₂ and C₂, H₆. The viscosity-temperature variation for all bitumens and gases is expressed as [log(μ + 0.8) = ± 10 T]. A linear cross-correlation between parameters b₁ and b₂ in the above relationship is identified and used subsequently to derive a one-parameter viscosity equation: [log(μ + 0.8) = θ(ΦT)^b]. where θ = 160, Φ = 0.008 for all bitumens and θ = -0.1, Φ = 0.015 for all gases. The two mixing rules examined in this study are: $ \log \left( {\bar \mu + 0.8} \right) = \sum v_i \,\log \left( {\mu _i + 0.8} \right) $ and $ \log \left( {\bar \mu + 0.8} \right) = \sum v_i \,\log \left( {\mu _i + 0.8} \right) + \sum \sum v_i v_j B_{ij} $, where v represents the geometric mean of mass and mole fractions and B_ij is a binary viscous interaction term. Predictions for the viscosity of gas-saturated bitumens are validated with over 400 experimental data points for five Alberta bitumens at temperatures from 12 to 120°C and pressures up to 10 MPa.     

Determination of intrinsic viscosity of polyelectrolyte solutions

Intramolecular hydrodynamic contribution η_intra/C to the reduced viscosity η_SP/C of polyelectrolyte solutions is derived as a function of polymer concentration C by separating the theoretically calculated intermolecular electrostatic contribution η_inter/C from the observed reduced viscosity, assuming an additivity, η_SP/C=η_intra/C+η_inter/C. The resulting intramolecular part η_intra/C reflects nearly the net effect of the polyion conformation; it increases monotonously with decreasing polymer concentration and levels off to a constant in sufficiently dilute concentrations. The leveling-off value of η_intra/C corresponds to the intrinsic viscosity [η]. From the estimated values of [η], the ionic strength I dependence of the polyion conformation has been visualized, resulting in a similarity between two relations, η_intra/C vs. C and [η] vs. I.     

Effect of inorganic salts on viscosity of acrylonitrile‐N‐vinylpyrrolidone copolymer solutions

Effects of inorganic salts on viscosities of dimethyl sulphoxide (DMSO) solutions of acrylonitrile(AN)/N‐vinylpyrrolidone(N‐VP) copolymer are discussed. Viscosity was determined by the rotary viscosimeter. It was shown that the solution viscosity decreases quickly with addition of KCl and NaCl and the effect of NaCl is more prominent than that of KCl. As concentration of KCl and NaCl went beyond 0.025 mol/L, the viscosity showed a trend of increase. The viscosity increased considerably with addition of FeCl₃ and CuCl₂. Changes in solution viscosity became less obvious with addition of ZnCl₂. As temperature increased, the viscosity of the copolymer solution containing NaCl decreased most quickly and the copolymer solution consisting of FeCl₃ showed the slowest decrease. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3492–3495, 2003     

Dilute solution properties of poly(3-dimethyl acryloyloxyethyl ammonium propiolactone)

The aqueous solution properties of an ampholytic poly(3-dimethylacryloyloxyethyl ammonium propiolactone), poly(DMAEAPL), are examined in this study by measuring reduced viscosity, intrinsic viscosity, degree of binding and dynamic light scattering. This polyampholyte's intrinsic viscosity is related to the type and concentration of the salt added. The intrinsic viscosity behaviour for the polyampholyte resulting from the associations of the polymer chains is in contrast with cationic and anionic polyelectrolyte. The polyampholyte in high concentration of NaCl has a low degree of binding, indicating that the proton ion (H⁺) has difficulty in binding to the carboxylate group (COO⁻) at the polymer end. The carboxybetaine, DMAEAPL, has a higher degree of binding than the corresponding sulfobetaine, DMAPS. Dynamic light scattering measurements indicate that the poly(carboxybetaine) diffusion coefficients decrease and the chain dimensions increase with an increasing salt concentration. The models proposed in this study can account for the poly(DMAEAPL) solution viscometrics and the degree of binding. © 1997 Elsevier Science Ltd.     

Dilute solution properties of naphthalene-labeled cationic poly(dimethyl sulfate quaternized acrylamide/N,N-dimethylaminopropylmaleimide copolymer)

The properties of a novel cationic, naphthalene-labeled cationic poly(dimethyl sulfate quaternized acrylamide/N,N-dimethylaminopropylmaleimide copolymer), poly-(DSQADMAPM)/NA in aqueous solution are examined in this study, measuring intrinsic viscosity, reduced viscosity, and ionic strength. This cationic poly(DSQADMAPM)/NA’s intrinsic viscosity is dependent on the type and concentration of salt added to the aqueous solution. The intrinsic viscosity behavior of the cationic poly(DSQADMAPM)/NA resulting from the electrostatic repulsive force of the polymer chain is contrasted with polyampholyte. Smaller anions such as F⁻ with a common cation (K⁺) are found to be the most difficult to be bound to the end group, indicating that a higher intrinsic viscosity of the poly(DSQADMAPM)/NA would be in KF salt aqueous solution. Smaller cations such as Li⁺ with a common anion (Cl⁻) are found to be the most difficult to be bound to the quaternary ammonium group, indicating that a higher intrinsic viscosity of the poly(DSQADMAPM)/NA would also be in LiCI salt aqueous solution. Models are proposed to account for the poly(DSQADMAPM)/NA solution viscometrics.     

影响航空润滑油粘度的因素探究

综述了近年来温度、压力和剪切力对航空润滑油粘度影响的研究进展,给出了温度-粘度、温度-压力-粘度的关系经验公式,并比较了润滑油关于剪切力的实验方法。不同分子量的润滑油的粘度统计分析表明,这些公式较好地拟合了润滑油的粘度变化;压力对润滑油粘度影响的经验公式计算表明,对于在高压条件下工作的润滑油,润滑油粘度受压力影响很大。     

粘度法测定高聚物相对分子量实验的改进

本文改进了粘度法测定高聚物相对分子量实验。提出了用单点法测高聚物溶液的特性粘度,是一种操作简便,所需溶液量少,测量时间短且精度较高的方法。     

用黏度法确定原油乳状液的合适破乳温度

使用旋转黏度计考察了油包水(W/O)型原油乳状液体系与原油乳状液加入破乳剂后的体系两者在表观黏度上的差别。分析了产生这些差别的原因,对其中出现的特殊现象给出了合理的解释。通过对比发现2种体系的黏度差值与适宜破乳温度存在一定的关系,并通过实验进一步验证了这种关系,为原油生产中确定适宜破乳温度提供了新途径。