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1.
双螺杆挤出机流场数值模拟中流道进出口边界条件的探讨   总被引:1,自引:0,他引:1  
在对双螺杆挤出机流场的数值模拟中,流道进出口边界条件的设置一直是一个颇具争议的问题。由于事先无法获得计算域进出口平面上的真实边界条件,研究人员在进行双螺杆挤出机的流场分析时,大都采用放松边界条件。为了考察放松边界条件对双螺杆挤出机流场数值模拟结果的影响,本文采用聚合物流动分析软件POLYFLOW,在流量恒定的前提下对双螺杆挤出机流道进出口给定三种不同分布形式的速度边界条件,对其流场进行了数值模拟。数值计算结果表明,在体积流量恒定的条件下,流道进出口不同分布形式的速度边界条件对流场的影响主要集中在进出口附近区域,但对离进出口边界较远的流场影响很小。一般而言,当计算域所对应的螺杆较长时,可以忽略流道进出口的放松边界条件所引起的误差;当计算域较短时,不宜直接采用放松边界条件,而应根据螺杆的实际构型.在计算域的进出口增加适当长度的发展段。  相似文献   

2.
采用CROSS模型表示聚氯乙烯(PVC)的黏度特征,使用POLYFLOW软件数值模拟了塑料注射成型机螺杆计量段螺槽中熔体在塑化过程的三维等温流场,求解和分析了3条参考直线、yz截面和xy截面上不同时刻螺槽中的压强场、速度场、剪切速率场和黏度场,数值计算的结果表明:在螺棱附近区域物料的剪切速率大,物料剪切稀化作用增强,物料黏度减小。并采用粒子运动轨迹示踪的方法研究了塑化过程中注塑机粒子运动轨迹。得知塑化过程中注塑机粒子运动轨迹比挤出机复杂得多,有三种典型的运动方式:一部分粒子边旋转边向负Z方向运动、另一部分粒子在旋转的同时先向负Z方向运动后向正Z方向运动,还有一部分粒子和边旋转边向正Z方向运动。  相似文献   

3.
直线加速器被广泛应用于国防、能源、医疗等多个领域,加速器粒子模拟可视化是研究大规模高能粒子运动规律的重要方法。本文利用 OpenGL 和 GLSL 混合编程,给出了一套针对直线加速器粒子的科学模拟可视化与可视分析的方案,可清晰展示粒子在加速过程中的整体状态和运动趋势,体现出高速粒子的分类属性及其变化规律,为直线加速器的诊断分析提供了有效的工具。  相似文献   

4.
粒子模拟是研究离散粒子和连续介质运动规律的常用方法.而大规模的粒子模拟通常借助高性能计算系统.近年来,得益于其众核架构,图形处理器(GPU)已成为高性能计算的重要设备,并被广泛用于大规模粒子模拟过程的加速.本文讨论了一种对GPU加速的分布式粒子模拟进行在线可视化的方法.在该方法中,GPU除了被用于加速粒子模拟过程外,也被用于数据到图像的快速转换.同时,并行绘制技术被用于分布式数据的可视化.通过本文所述的方法,用户可在并行计算运行过程中,通过显示于拼接显示墙的高分辨率图像,实时地观察到粒子模拟中发生的现象,并对计算过程进行跟踪和调整.  相似文献   

5.
文章介绍了以8031单片机作核心控制部件的双螺杆挤出机内温度实时控制系统,并详细介绍了该系统的软硬件实施手段及系统特点。  相似文献   

6.
介绍了双螺杆挤出机计算机监控系统的实现,其中包括监控系统硬件和软件的结构设计,以及该监控系统的特点。  相似文献   

7.
介绍了双螺杆挤出机计算机监控系统的实现,其中包括监控系统硬件和软件的结构设计,以及该监控系统的特点。  相似文献   

8.
双螺杆挤出造粒机组主要用于塑料化工原料的改性、增强、回收等生产 ,是化工行业重要的机电一体化装备。根据生产工艺需要 ,各种原料和添加剂必须按一定的配比精确、可靠地称量并充分混合 ,以保证挤出机进料的稳定性能。一种典型的配混料系统结构如图1所示。配混料系统主要是由上料、配料和混料三部分组成。其工作原理是 :弹簧上料机根据各贮料罐的高、低料位计的状态自动控制上料电机的启动和停止 ,以保证贮料罐中有一定的物料 ,为启动配料做好准备。根图 1 配料系统结构图据工艺要求 ,设定每次称量中各种原料的重量 ,通过喂料变频器快、…  相似文献   

9.
单一的跟踪方法存在较大的局限性,为提高增强现实中跟踪环节的实时性和准确性,针对视觉跟踪和磁力跟踪的特点进行研究,提出了一种基于自适应粒子滤波的混合跟踪算法,用于对头部运动轨迹估计。该算法通过分析系统状态,自适应地融合多传感器数据,并建立相应的状态转移模型和系统量测模型;另外,该算法能在非线性非高斯的环境下动态地改变滤波器的粒子数和噪声方差,最终实现对头部运动轨迹的实时、正确估计。实验结果表明,该算法能有效地提高基于视觉和磁的混合跟踪的鲁棒性和运动估计的准确性。  相似文献   

10.
双螺杆制冷压缩机在商用制冷与空调领域得到越来越广泛的应用。本文着重介绍了一套双螺杆制冷压缩机转子计算机辅助设计系统,对系统的设计思路进行了阐述,然后详细说明了系统各部分基于NURBS的数学模型和在VC++环境下的实现方法,并对前人的设计思想进行了开拓创新,完成了一套具有自己特色的设计系统。  相似文献   

11.
The twin-screw configuration problem (TSCP) arises in the context of polymer processing, where twin-screw extruders are used to prepare polymer blends, compounds or composites. The goal of the TSCP is to define the configuration of a screw from a given set of screw elements. The TSCP can be seen as a sequencing problem as the order of the screw elements on the screw axis has to be defined. It is also inherently a multi-objective problem since processing has to optimize various conflicting parameters related to the degree of mixing, shear rate, or mechanical energy input among others. In this article, we develop hybrid algorithms to tackle the bi-objective TSCP. The hybrid algorithms combine different local search procedures, including Pareto local search and two phase local search algorithms, with two different population-based algorithms, namely a multi-objective evolutionary algorithm and a multi-objective ant colony optimization algorithm. The experimental evaluation of these approaches shows that the best hybrid designs, combining Pareto local search with a multi-objective ant colony optimization approach, outperform the best algorithms that have been previously proposed for the TSCP.  相似文献   

12.
Smoothed particle hydrodynamics (SPH) has become increasingly important during recent decades. Its meshless nature, inherent representation of convective transport and ability to simulate free surface flows make SPH particularly promising with regard to simulations of industrial mixing devices for high-viscous fluids, which often have complex rotating geometries and partially filled regions (e.g., twin-screw extruders). However, incorporating the required geometries remains a challenge in SPH since the most obvious and most common ways to model solid walls are based on particles (i.e., boundary particles and ghost particles), which leads to complications with arbitrarily-curved wall surfaces. To overcome this problem, we developed a systematic method for determining an adequate interaction between SPH particles and a continuous wall surface based on the underlying SPH equations. We tested our new approach by using the open-source particle simulator “LIGGGHTS” and comparing the velocity profiles to analytical solutions and SPH simulations with boundary particles. Finally, we followed the evolution of a tracer in a twin-cam mixer during the rotation, which was experimentally and numerically studied by several other authors, and ascertained good agreement with our results. This supports the validity of our newly-developed wall interaction method, which constitutes a step forward in SPH simulations of complex geometries.  相似文献   

13.
We develop a miniaturized batch-type screw mixer (BSM) for uniform mixing of polymer resin and nanoparticles, based on the stretching of material elements. This stretching is induced by the combination of recirculating cross-sectional flows in deep channels of the screw and high shear stress developed at flight regions. The BSM is used to produce a polymer nano-composite composed of multi-walled carbon nanotubes and polydimethylsiloxane resin. The mixing performance of the BSM is characterized quantitatively by estimating two different types of mixing efficiencies (i.e., dispersive mixing and distributive mixing) via transmitted light microscope images. The developed BSM highly improves the mixing performance rather than that of a conventional ultrasonic mixing device.  相似文献   

14.
双螺杆挤出压片机的螺杆电机由于受到负载的非线性影响,使得压片机系统的鲁棒性较差;根据模糊控制器对参数变化不敏感,鲁棒性强的优点,采用模糊控制器来控制螺杆电机调速,可提高螺杆电机的鲁棒性,改良双螺杆挤出压片机的机器性能;通过MATLAB/Simulink仿真软件,建立一个带有模糊控制器的双螺杆挤出压片机螺杆直流电机控制系统模型;仿真试验表明,模糊控制器在电机调速中的应用是可行的;该方法改良了电机调速系统的性能,提高了压片机控制系统的适应能力和鲁棒性。  相似文献   

15.
随着计算机和计算技术的飞速发展,数值计算与实验研究和理论研究成为科学研究的3种重要方法. 近年来,越来越多的人使用成熟的计算流体力学(Computational Fluid Dynamics, CFD)软件,数值仿真动态模拟聚合物螺杆挤出过程,深入研究螺杆结构、工艺条件和物性之间的规律,研究各类参数对聚合物挤出过程的影响和聚合物螺杆挤出机理. 数值计算作为新的研究手段之一,不但能大大缩短研发周期和降低成本,而且可得到实验手段无法测量的数据. 为了推动数值计算在该领域的应用,综述国内外数值研究螺杆挤出机螺纹元件性能的进展.  相似文献   

16.
席世亮  姜南  吴大鸣  侯贵海 《计算机仿真》2003,20(12):130-132,150
该文论及的是单螺杆挤出过程的计算机仿真。从挤出过程的数学模型分析入手,使用可视化程序语言Visual C 6.0,OpenGL,Access97等软件,开发了完全基于Windows的单螺杆挤出过程的仿真系统。该系统能近似地模拟挤出过程,并预测挤出机的质量流率、沿螺槽的压力和温度分布、固体床的分布,以及能量消耗。这为优化单螺杆挤出机设计,并控制加工过程以获得理想的产品,提供了科学依据和设计分析手段。  相似文献   

17.
用国产压电陶瓷晶片研制出压电式振动给料器 ,并对其主要部件结构参数进行了优化研究 ,还研制出驱动压电式振动给料器的智能化多功能电源 ,该压电式振动给料器由于具有多项优良品质可望成为振动给料器的换代产品。  相似文献   

18.
To know how much misalignment is tolerable for a particle accelerator is an important input for the design of these machines. In particle accelerators the beam must be guided and focused using bending magnets and magnetic lenses, respectively. The alignment of the lenses along a transport line aims to ensure that the beam passes through their optical axes and represents a critical point in the assembly of the machine. There are more and more accelerators in the world, many of which are very small machines. Because the existing literature and programs are mostly targeted for large machines, in this work we describe a method suitable for small machines. This method consists in determining statistically the alignment tolerance in a set of lenses. Differently from the methods used in standard simulation codes for particle accelerators, the statistical method we propose makes it possible to evaluate particle losses as a function of the alignment accuracy of the optical elements in a transport line. Results for 100 keV electrons, on the 3.5-m long conforming beam stage of the IFUSP Microtron are presented as an example of use.  相似文献   

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