电磁动态密炼机四棱异步剪切型转子的设计及模拟分析

设计电磁动态密炼机四棱异步剪切型转子,建立在电磁振动条件下转子的三维数学模型,并运用专业流体软件Polyflow动态模拟分析转子流场的压力场、速度场、剪切速率分布、粘度分布、混合指数分布和浓度场。结果表明:在电磁振动条件下,转子流场出现最高压力、最大速度、最大剪切速率和最大质量浓度的时间缩短,转子突棱处的粘度很小,转子平滑处的粘度较大,混合指数较小,从而使胶料快速完成混炼,提高混炼效率,降低混炼能耗。     

丙烯酸树脂旋转粘度测定影响因素的探讨

通过对丙烯酸树脂样品旋转粘度测量中有无气泡、转子位置、转子液位标线、样品均匀程度、实验温度、转子转速等影响因素进行试验,文章具体探讨了这些因素对粘度分析测定结果的影响。     

未硫化橡胶门尼粘度测量不确定度的评定

通过门尼粘度检测整个过程进行不确定评定度分析,找出引起不确定度产生的因素。评定确认:转子上、下面空隙以及转子转速是影响结果的最主要因素,转子厚度、转子侧面空隙引入的不确定度也应引起重视。此方法对用圆盘剪切粘度计进行未硫化橡胶门尼粘度测定的不确定度评定具有借鉴和参考作用。     

密炼机转子对混炼能力的影响

试验研究密炼机四棱切线转子、同步转子和ZZ2转子等不同转子类型对生产效率的影响.结果表明,在生产门尼粘度相同或相近腔料时,四梭切线转子所用时间最短,同步转子所用时间较长,ZZ2转子所用时间最长.在制定转子转速和容量等工艺参数时,应充分考虑各种转子的特点,充分发挥密炼机的生产能力.     

二棱功能型同步转子结构及混炼效果有限元分析

根据混炼过程中对密炼机转子分布和分散作用的要求,综合剪切型转子和啮合型转子的优点,设计了二棱功能型同步转子.采用有限元方法对其混炼过程中胶料的剪应力、压力.粘度和速度矢量进行分析,结果表明二棱功能型同步转子可使胶料得到很好的分布和分散效果.     

流体粘度对转子流量计读数的影响

转子流量计是实验室中用得最广泛的流量计量器具，本文叙述了粘度影响转子流量计示值的原因，用图例揭示了不同粘度引起示值变化的现象。     

密炼机拉伸型转子流场模拟及试验研究

对密炼机拉伸型转子进行设计,并与普通四棱转子一同进行流场模拟与分析,然后进行试验验证。结果表明,拉伸型转子在工作状态下的压力场、速度场、粘度场均优于普通四棱转子;采用拉伸型转子制备的胶料混炼能耗小于以及物理性能和炭黑分散性能优于采用普通四棱转子制备的胶料。     

共流型转子的有限元分析

通过建立共流型转子的物理模型、数学模型和有限元模型,并运用POLYFLOW有限元分析软件对共流型转子的混炼过程进行了模拟。通过对混炼过程的速度场和粘度场的求解计算,证明共流型转子具有较好的分散和分布混合功能。     

混炼胶门尼粘度曲线异常的分析与处理

对混炼胶门尼粘度曲线出现异常的情况进行分析,并提出相应的处理方法。造成混炼胶门尼粘度曲线异常的主要原因包括试样厚度不合适、遗留胶、传感器或电路板故障、减速箱磨损、转子磨损和加热丝烧断等。可根据胶料门尼粘度曲线异常情况分析,对相应部位进行清理或更换元件,保证门尼粘度测定结果的稳定性。     

漫话橡胶测试仪器设备（三）

三、橡胶门尼粘度计橡胶门尼粘度计主要用来测定生胶或混炼胶门尼粘度以及胶料的焦烧时间和硫化速度。所谓门尼粘度即用门尼粘度计测得的生胶或混炼胶的粘度,也就是在一定的温度、时间、压力下,被测胶样对门尼粘度计转子的转动所产生剪切力矩的大小。由于胶料的塑性不同,转子所承受的剪切力矩的大小也不同。这表现在显示装置上的数值越大,即门尼值越大,门尼粘度越高,也就是塑性越低。以门尼粘度计测定的门尼焦烧则是以时间表示混炼胶初期硫化特征的。它是根据被测胶样门尼粘度的变化,来测定在一定温度下开始出现硫化现象的时间,其转…     

高黏羟丙基甲基纤维素的黏度测试方法研究

利用国产NDJ-1型旋转黏度计和美国Brookfield(LVDV-I+)黏度计,研究了黏度大于105mPa·s的羟丙基甲基纤维素(HPMC)的黏度测试方法,并进行了对比黏度测试。结果表明,对于2%水溶液黏度小于105mPa·s的HPMC,NDJ-1型旋转黏度计的1#、2#、3#、4#转子分别对应于Brookfield黏度计的61#、62#、63#、64#转子,在转速相同时测试结果是一致的。对于2%水溶液黏度大于105mPa·s的HPMC,用NDJ-1型旋转黏度计测试时需通过1%水溶液黏度换算系数得到2%水溶液黏度,方法相对比较繁琐,且不适于实际应用;用Brookfield(LVDV-I+)黏度计测试时,由于测试范围较宽,能够得到比较精确的黏度数值,更适于实际操作和应用。     

立磨选粉机叶片结构对分级区速度场影响分析

立磨选粉机分级区速度场是影响其分级性能的主要因素之一,其机内气固两相流为非理想流体。本文应用流体力学流体黏滞性与速度梯度原理,分析了速度梯度过大造成选粉机选粉精度和选粉效率下降的机理。通过构建不同叶片结构转笼的立磨选粉机模型,采用Fluent软件模拟分析了立磨选粉机不同叶片结构转笼的分级区速度场中速度流向、速度大小与速度梯度的变化规律。进行了立磨选粉机转笼叶片结构改造试验,试验表明：改造后的Z形叶片结构转笼的立磨选粉机产量在直叶片转笼结构的基础上提高了15 t/h,且0.08 mm颗粒的筛余降低了10%。     

双转子连续混炼机混合过程物理模型的建立

建立了双转子连续混炼混合过程的物理模型，分析了影响其混炼段融体输送过程和混合过程的主要因素，并提出：转子混炼段融体输送量与转子螺棱几何形状，物料粘度，混炼段融体压降等有关；转子对物料的混合过程与转子组合（螺棱交汇区长度）转子螺棱几何形状，转子转速等因素有关。     

输油转子泵啮合间隙与转子叶数对泵性能影响规律研究

为了提高输油转子泵腔内部流动稳定性,同时提高泵的容积效率,建立了5种啮合间隙、3种转子叶数的输油转子泵模型进行对比分析。基于动网格技术和SSTκ-ω湍流模型对输油转子泵腔内部进行数值模拟,并通过试验验证了研究方法的可行性,分别研究了啮合间隙、转子叶数对输油转子泵性能影响规律,并对输油转子泵的啮合间隙、转子叶数进行了优化设计。结果表明,啮合间隙从0.1 mm增至0.3 mm,2叶输油转子泵腔内高速流动区域扩大,转子腔内漩涡强度增大,泵腔内流体流动的平稳性和容积效率降低;转子叶数由2增加为4,转子腔内压力变化的多样性增加,3叶转子泵腔内流体流动最平稳。优化设计的输油转子泵腔内流动平稳性得到提高,同时容积效率提高了2.1%,能更好地满足油田输油的需要。     

折流式旋转床液相功耗数学模型

折流式旋转床是新型的超重力旋转床,其转子由安装动折流圈的动盘与安装静折流圈的静盘上下相互嵌套而成。液体在转子中流动,把转子分成数个膜流区。对膜流区建立了液相功耗的理论数学模型,求解模型得到了液相功耗计算值。实验在转子直径600mm、高度80mm的折流式旋转床中进行,物系为水,测得了液相功耗的实验值。比较了模型计算值和实验测量值,两者比较接近,实验值是计算值的0.611～0.820倍。根据液相功耗数学模型,得出液相功耗与液体流量、液体密度呈正比,与转速的平方呈正比。该模型的建立为旋转床液相功耗的研究提供了一定的理论基础。     

Dispersion,temperature and torque models for an internal mixer

Models based on kinetic, thermodynamic and rheological equations have been developed to compute dispersion extent, batch temperature and relative batch viscosity at discrete intervals during a mix cycle in an internal mixer. The calculated relative bulk viscosity can be linked empirically to a measured variable such as rotor torque or power consumption. Solution of the models over successive time intervals allows the computation of complete dispersion, temperature, and torque/power profiles for a mix cycle. The mix models exhibit good fits to experimental torque and temperature curves for mixing natural rubber with carbon black over a wide range of carbon black loadings (0 to 50 phr) for rotor speeds ranging from 40 to 70 RPM in two lab‐scale internal mixers. The models are shown to be suitable for moderately reinforcing (ASTM N660) as well as highly reinforcing (ASTM N121) grades of carbon black. Rate constants for filler dispersion, incorporation and erosion can be extracted from the models and can be interpolated to generate dispersion, temperature and torque curves at new conditions of carbon black loading and rotor speed. The mix models could thus be used for process‐control purposes and for specifying drop targets based on batch properties in addition to the time‐temperature‐energy criteria typically used today. Polym. Eng. Sci. 44:1247–1257, 2004. © 2004 Society of Plastics Engineers.     

基于剪切流变的密炼机混炼胶料粘度-时间数学模型

从剪切流变对胶料粘度的影响入手,建立简化的粘度-时间模型,用于描述混炼过程中胶料粘度与密炼机结构和工艺参数间的数学关系.采用MATLAB数学软件,选择4阶曲线对不同转子转速下的试验数据进行数值拟合,求出模型中温度对时间的变化率,得到混炼阶段胶料粘度-时间曲线,并通过试验对其进行修正,得出在特定的混炼阶段中胶料粘度-时间的数学模型.该模型可用于预测密炼机混炼过程中胶料的粘度.     

有机工质向心透平变工况特性的数值模拟与极差分析

以R245fa为工质设计向心透平,采用CFD方法对向心透平性能进行全流域三维模拟研究,考察了入口温度、转子转速和膨胀比(进出口压力比)对向心透平工况特性的影响,对主要影响因素进行极差分析。结果表明,向心透平工作转速为设计转速的80%~100%时,输出功率和等熵效率波动较小,工作转速高于设计值时透平性能迅速下降。随入口温度升高,透平输出功率与等熵效率增大;随膨胀比增大,透平输出功率线性增加。透平存在最佳膨胀比使等熵效率最大,且实际运行压比大于最佳膨胀比时,透平等熵效率变化较小。出口压力对向心透平输出功率影响最大,温度的影响最小;转子转速对等熵效率影响最大,入口压力的影响最小。     

Droplet break-up by in-line Silverson rotor–stator mixer

Silverson high shear in-line rotor–stator mixers are widely applied in industry for the manufacture of emulsion-based products but the current understanding of droplet breakage and coalescence in these devices is limited. The aim of this paper is to increase the understanding of droplet break-up mechanisms and to identify appropriate literature correlations for in-line rotor–stator mixers. Silicone oils with viscosities ranging from 9.4 to 969 mPa s were emulsified with surfactant in an in-line Silverson at rotor speeds up to 11,000 rpm and flow rates up to 5 tonnes/h. The effect of rotor speed, flow rate, dispersed phase fraction up to 50 wt%, inlet drop size and viscosity ratio on droplet size was investigated. It was found that rotor speed and dispersed phase viscosity have a significant effect on the droplet size, while flow rate, inlet droplet size, viscosity ratio and dispersed phase volume have a lesser effect. The results indicate that low viscosity droplets are broken by turbulent inertial stresses, while droplets smaller than the Kolmogorov length scale are broken by a combination of inertial and viscous stresses. It also appears that the weak dependence of drop size on flow rate enables the energy efficiency of an in-line high shear Silverson to be significantly improved by operating at as high a flow rate as possible.     

The effect of stator geometry on the flow pattern and energy dissipation rate in a rotor–stator mixer

The effect of stator geometry on the flow pattern and energy dissipation rate in a batch rotor–stator mixer has been investigated using sliding mesh method with standard k–? turbulence model. It has been found that for the stators with narrow openings (small width-to-depth ratio) the liquid at certain distance from stator rotated in the opposite direction to the rotor rotation. This opposite rotation was induced by the strong circulation flows behind the jets. The predicted power numbers for the stators with circular and square openings were about 10% lower than experimental data and the power number for stator with slot openings was about 20% lower. The simulation results showed that the power number was proportional to the total flowrate. For all stators, about 50–60% of energy supplied by the rotor dissipated in the rotor swept region and approximately 25% in the jet region. The fraction of energy dissipated in the hole region was 12–15% for stators with narrow opening and only 8% for stator with wide opening. The order of magnitude of energy dissipation rate in each region (rotor swept region, holes and jets) was practically the same for all stators; however, the distribution of energy dissipation rate in the hole was more uniform in stator with narrow openings.