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1.
曾宪文  孙启国  吕洪波 《机械》2013,(12):29-32
根据一种新的油气混合原理,在混合腔体中加入一个锥形体,设计了一种新型油气混合器,并利用FLUENT对三种不同混合体锥度的油气混合器内流场进行了仿真分析。仿真实验结果显示:锥体锥度对油气两相环状流的形成和周向分布均匀性有一定影响;选择合理的锥度有利于提高混合器性能。  相似文献   

2.
《机械科学与技术》2017,(5):755-760
应用CFD技术研究了椭圆螺旋流道内两相液体在充分发展条件下的混合效果。基于FLUENT软件,对混合性能进行了数值模拟研究,讨论了椭圆螺旋管道混合器的截面形状、曲率半径、螺距3种因素对该混合器混合效果的影响。模拟所得液相的流动状态与实验结果具有很好的一致性。提取相应截面液体的混合不均匀系数,分析结果表明:截面形状的变化会给螺旋管道混合器造成不同程度的狭小区域,对混合均匀性影响较大;增加螺距会对混合产生消极的影响;当曲径为某一特征值时,混合效果可达到最好状态;同时,通过仿真分析得出,液体流速的改变对混合器中液体的混合效果影响不大;通过对流场内部剪切速率、流线、质点速度场的分析,讨论了粒子无序运动是螺旋混合器内液体充分混合的关键因素。  相似文献   

3.
针对稠油掺稀降黏开采过程中稠油与稀油混合不均匀的问题,设计了一种新型混合器,采用一个涡轮式叶轮和折叶式叶轮组合的方式,并且通过键与轴连接,两个叶轮一起联动。采用FLUENT 6DOF模型,对混合器的混合效果进行了仿真分析,从叶轮旋转速度、稀油体积分数、涡旋性3个方面进行评价。结果表明,新型混合器虽然旋转速度有所下降,但是稀油分布更加均匀,具有更强的涡旋速度,说明新型混合器比现有混合器具有更好的混合效果。  相似文献   

4.
在真空状态下,为将混合时间尺度小、粘度较高的不同液体快速均匀混合,提出了一种带有挤压槽轮和搅拌叶轮的动态混合器,介绍了这种动态混合器的结构原理和混合机理。基于FLUENT中的动网格模型、Mixture多相流模型、RNGκ-ε湍流模型及PISO算法,对混合器预混合管道不同出口位置、叶片数量、叶轮转速等不同条件下的两相流混合效果进行了数值模拟,结果表明:预混合管道出口位置不同时,混合效果不同;当叶片数量为16时,混合效果最理想;模拟还表明,增加叶轮旋转速度对混合效果作用明显,但是达到一定转速后,混合效果趋于稳定。在此基础上,通过液体质点运动矢量图、速度流线图和湍动强度分布云图,分析了加速溶液混合均匀的是叶轮二次剪切和混合器中运动部件对流场的湍动作用,选用环氧树脂(E51)与对应的固化剂进行混合并浇注成型,并对制品的硬度进行了测试,实验结果表明该混合器混合性能可靠。  相似文献   

5.
简述喷射式煤气混合器的结构特点、混合机理及混合形态.根据煤气混合器在煤气混合系统中的用途,介绍以高炉煤气中混入石油液化气的煤气混合器的设计和应用.  相似文献   

6.
微混合器作为一种可以实现快速、高效的混合设备在生物分析、化学反应和检测等领域中应用,特斯拉阀因其简单的结构和特殊的流动机理常应用于微混合器的结构设计中。为提高混合效率,在特斯拉型混合器中添加菱形障碍物,并基于流场分析对其布局进行了优化和实验验证。以混合率和压降比值最大为优化目标对菱形障碍物在特斯拉型微混合器布局进行优化,经过优化得最优菱形障碍物尺寸为46.35 μm,最优横向偏移量为18.78 μm,最优竖向偏移量为20 μm。基于优化结果,设计并制作了添加菱形障碍物的特斯拉型微混合器并对微混合器的混合效果进行实验验证。结果表明设计优化的菱形障碍物特斯拉型微混合器与未添加障碍物时的特斯拉型微混合器相比在相同条件下具有更高的混合效率。  相似文献   

7.
对长翼型内置翼片静态混合器进行了研究与优化。以流动方向为基准进行横向偏转,大小分别为0°(原模型)、15°、30°、45°。在雷诺数5000的情况下,应用CFD软件FLUENT模拟了液液两相混合过程,其中混合模型和湍流模型分别采用组分输运方程和标准k-ε模型。用不均匀系数COV值表征混合效果,结果显示随着角度变大,COV值先降低后增高,压力损失不断降低。综合考虑模拟混合效果和压力损失,偏转30°的结构具有最佳性能。  相似文献   

8.
按照混沌混合理论构建了Smale、Helical和Baker三种微混合器,为研究其混合机理与混合效果,对不同雷诺数下的对流扩散和混合进行了数值模拟,并用实验结果进行了验证。结果发现:实验结果与数值模拟结果吻合得很好。在低雷诺数下,由于Baker微混合器中流体的分层作用强,明显增大了流体的接触面积,也加快了流体混合速度,其混合效果要明显优于另外两种混合器;然而,在较大的雷诺数下,Smale微混合器中流体混合效果则优于Baker微混合器,其原因是Smale微混合器的分层效果虽然不如Baker微混合器,但其对流作用明显强于Baker微混合器;Helical微混合器因没有分层作用,其混合主要依赖于对流,所以在低雷诺数下混合性能较差,而高雷诺数下混合性能有所提高。  相似文献   

9.
介绍了化工过程强化中新型化工设备--静态混合器以及计算流体力学和激光测速技术在静态混合器的微观应用基础理论中的应用和研究进展;由于静态混合器具有特殊的结构特点与传统的搅拌混合设备相比表现出了高效、节能等优点,静态混合器在硝化工业和环氧丙烷装置的扩产改造中成功应用并且取得了巨大社会效益和经济效益.  相似文献   

10.
在常见类型混合器的基础上设计了一种新型的高粘度两相流静态混合器。基于Fluent软件分析了预混单元对整体混合效果的影响,并分析了混合单元数量和流体入口速度对混合均匀度的影响。分析结果表明带预混单元混合器的混合效果好于不带混合单元的,还表明当混合单元数量为3时能在不同的入口速度下获得理想的混合效果。在此基础上,根据质点的速度场和流场分布状态,分析并说明了杂乱的速度和流线分布是获得良好混合效果的根本原因。同时,通过仿真分析了粘度对混合效果的影响,结果表明该混合器的混合均匀度随着液体粘度的增大而提高,还表明该混合器对中、低粘度的液体也有良好的混合效果。  相似文献   

11.
We have performed a comparative study on mechanical property and dimensional stability of substrates for magnetic tapes. The substrates include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and aromatic polyamide (ARAMID), which could be used for linear-type magnetic tapes for computer data storage. We have demonstrated that ARAMID is the most attractive substrate and that PET has the advantage of considerably smaller irreversible creep deformation and lateral contraction caused by tension as compared to PEN film. In this paper, we also introduce recently developed PET (Advanced PET) with higher glass transition temperature compared to conventional PET; moreover, we discuss the relationship between film properties and polymeric structures of these substrates.  相似文献   

12.
Pluta microscope used to throw light on the effect of heat treatment time on the different properties of poly (ethylene terephthalate) PET fibers. PET fibers were annealed at times ranged from 5 to 30 min at different temperatures (150, 170, 190, 210°C) using two different processes (fast cooling and slow cooling processes) in air. The refractive indices, the shrinkage, orientation factor and crystallinity of PET fibers were determined for different annealing temperature during the short time treatment. The shrinkage percentage and degree of crystallinity increased with increasing the temperature and time of annealing. Microinterferograms are given for illustration.  相似文献   

13.
成核剂对聚对苯二甲酸乙二醇酯的结晶行为影响   总被引:1,自引:0,他引:1  
在HAAKE转矩流变仪中进行了聚对苯二甲酸乙二醇酯(PET)和不同类型成核剂的熔融共混,采用差示扫描量热仪(DSC)研究了不同粘度纯PET、纯PBT及添加小分子成核剂、高分子成核剂、复合成核剂的PET非等温结晶过程。通过红外光谱(FTIR)、热台偏光显微镜(POM)和扫描电镜(SEM)对添加成核剂前后PET的结晶形貌进行对比分析。结果表明低粘度PET的结晶能力较中粘度和高粘度的PET结晶能力强,添加成核剂后PET的结晶峰温移向高温、半结晶时间缩短、结晶速率常数增大。其中高分子成核剂、复合成核剂对PET结晶行为改善效果更好,其成核机理为化学成核,但高分子成核剂不会造成PET分子链的降解。  相似文献   

14.
A technique of using a CO-3 calibration block for measuring not only the base of a piezoelectric transducer (PET) but also its incidence angle is proposed. This approach allows a single specimen to be used in an automated PET certification system for obtaining its main characteristics. The results of measuring the PET incidence angle in an automated mode on a CO-3 block are compared with the measurement results on CO-2 according to GOST (State Standard) 14782–86. It is shown that systematic error is absent. The use of a CO-3 block substantially reduces the time of obtaining the basic characteristics of a PET and simplifies the calibration procedure.  相似文献   

15.
In this paper, Electromagnetic interference (EMI) shielding mesh filter films are fabricated using the screen printing method. An EMI shielding mesh filter requires fine line patterns under 30 μm, therefore, the screen masks with fine-line screen mesh, as well as suitable ink composed of fine metal particles are required. Moreover, because the printed EMI shielding filter has to be fabricated on a PET film, the ink should be sintered at a temperature below 150°C not to deform the film. For the purposes of this study, a screen mesh with a mask of 20 μm line, and ink made nano silver paste with a sintering temperature of 140°oC, which could guarantee fine-line patterning on the PET, were used. The ink had a viscosity of 90,000–12,000 cps and metal content of 85% in weight. The printed EMI shielding mesh had a line width of about 24 μm and a thickness of about 2.5 μm. The measured surface resistance was 0.5∼0.7 ω/□, offering good electrical performance as an EMI mesh. A simple measurement system was used to evaluate the electrical shielding performance of the printed EMI shielding mesh. A comparison of the printed EMI shielding mesh with pure film without mesh and copper sheet revealed that the printed EMI shielding mesh is indeed capable of providing good electrical performance.  相似文献   

16.
For flexible electronics in manufacture, the full-field stress measurement is an important issue for the film deposited on the flexible substrate. In this work, the two-dimensional photoelasticity is proposed to measure stress-optical coefficients and an analytical derivation is carried out for investigation on full-field residual stresses under tensional forces. In experimental setup, a polarization beam splitter (PBS) is used to connect with two CCD cameras that are used to capture the intensity of right-hand and left-hand circular polarization separately. It has higher measured speed and better uniformity than a direct rotation method. Stress-optical coefficients can be calculated by extracting the slope from tensional stress versus optical retardation curve. Experimental results show that optical retardations for indium-tin-oxide (ITO)-coated PET (polyethylene terephthalate) substrates can be affected more easily than PET substrates under tensional forces. The difference of stress-optical coefficients between 0° and 90° orientations for PEN (polyethylene naphthalate) substrates is smaller than that for PET substrates. Furthermore, it shows residual stresses for ITO-coated PET substrates in 0° and 90° orientations are different under tensional stress.  相似文献   

17.
Endovascular aneurysm repair (EVAR) is a type of endovascular surgery used to treat abdominal aortic aneurysms (AAA). The prosthesis used for the purpose, called stent-grafts, are made of polymeric materials reinforced by metallic stents. The polymers used for the graft construction are usually woven PET fibres or extruded ePTFE. After implantation and due to blood flow and to the relative motion between the stent and the graft, abrasion, erosion and fatigue of the graft material can occur, leading to fibre separation/fracture and perforation of the graft. In this paper, abrasion wear tests results are presented for three different materials used in stent–grafts, using the Martindale method. Mass loss as function of wear cycles is presented. Scanning electron microscopy, before and after tests was used to analyse the materials surface. ePTFE specimens presented ruptures between 45,000 and 55,000 cycles and PET specimens at 70,000 cycles. PET-LP (low profile) specimens did not reveal any rupture until 150,000 cycles. These results show an increased life resistance, due to different wear mechanisms of PET-LP fabric, when compared with ePTFE and PET fabric for vascular prosthesis applications.  相似文献   

18.
设计了一种PET瓶瓶盖和液位检测机,通过新颖的机械结构设计、相机架构、光学镜片的设计以及稳定的图像处理算法,解决了目前人工检测、传感器检测、计算机视觉检测等方法检测的缺陷和不足,可快速、精确地检测PET瓶瓶盖和液位的质量。  相似文献   

19.
A method for fabricating a microlens array composite optical film by a seamless roller mold of self-assembly is presented. The roller with a lot of random cavities is used to produce a polyethylene terephthalate (PET) composite optical film with 3D random microlens arrays using the ultraviolet (UV) roll-to-roll printing. The luminance gain and haze are 1.247 and 86 %, respectively, giving the PET composite optical film the properties of a brightness enhancement film and a diffuser. Solid glass beads (SBs) are used for parameter testing for self-assembly. Then, 3 M glass bubble beads (BBs) are used to fabricate a seamless roller mold. The optimal parameters of the self-assembly process for the SB are a coating speed of 135 mm/h with a 39 % volume ratio, and those for the BB are a coating speed of 30 mm/h with a 3 % volume ratio. Finally, the PET optical film is used in the green energy lighting testing of a commercial bicycle light-emitting diode (LED). The results show increased lighting angle and light uniformity, making it similar to traditional tungsten light.  相似文献   

20.
多主色LED照明光源的相关色温调控   总被引:2,自引:0,他引:2  
通过建立光电热(PET)模型,研究了发光二极管(LED)光源相关色温(CCT)的模型预测控制方法,实现了多主色LED光源的相关色温控制。首先,提出了热平衡状态稳定假设和修正的非对称高斯函数作为基函数的假设;根据软模型建模思路,用最小二乘估计求解各个模型参量的回归子模型,分析光谱敏感系数曲线随CCT变化的关系。然后,通过重力线法调试出在3 000,4 500和6 500K下3个常用色温点处所需的电流控制量。最后,在调设好的电流控制量上加以一定的无规则扰动产生一组验证数据,用于评价模型精度。实验结果表明:建立的多主色LED光源的PET数学模型能够很好地通过电流控制量和环境温度来预测LED的热沉温度和多主色合成光谱功率分布函数,进而能够预测控制色温,具有很好的模型精度。得到的色度坐标预测精度优于±0.005,CCT预测精度优于±150K。提出的基于模型的控制方法不仅适用于常用LED光源的CCT调控,还可推广到更多通道的LED光源的色度及CCT控制中。  相似文献   

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