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1.
The structure and operating principle of micro valveless pump were investigated theoretically and experimentally. The mathematical
model of pressure and flow rate within the micro nozzle/diffuser was established to analyze the effects of nozzle/diffuser
parameters on the output flow rate of the micro valveless pump. The experiments were carried out with different structural
parameters, driving frequencies, vibration amplitudes and stiffness of the driving diaphragms. Effects of the structural parameters
and driving conditions on the operation performance of the pump are discussed in detail. The work provides useful reference
for structure optimization selection of the driving diaphragm of micro valveless pump.
Project supported by National Natural Science Foundation of China (Nos. 50175098, 59835160) 相似文献
2.
对下喷自吸环流反应器内气－液两相流和气－液－团三相流体系的液相局部流动特性进行了实验研究．用改进皮托管对液相瞬时速度进行了测量，并借助湍流统计理论对渡相平均速度、液相湍动速度和湍动微尺度等液相局部流动参数进行了统计分析和处理，着重讨论了喷射液体流量和固体粒子加入量分别对喷射有效区和导流筒内管流区液相局部流动参数的影响． 相似文献
3.
等离子割炬工作原理复杂,喷嘴在冷却水温度场和流场耦合作用下工作,实物实验难度较大,文章采用CFD软件针对两种割炬喷嘴进行数值模拟,分析在不同冷却水流速度下的温度云图和温度曲线图,确定喷嘴结构,给出建议冷却水流速度。 相似文献
4.
The shapes and geometrical parameters of nozzles are key factors for fluidics. The relationship among the reaction thrust, flow rate pressure, diameter do and length L of a cylinder nozzle is analyzed theoretically. The simulation of the flow field characteristics was conducted via the FLUENT computational fluid dynamics package. Effects of the inlet conditions and the nozzle dimensions on the reaction thrust of a water jet were addressed particularly. The reaction thrust experiments were performed on a custom-designed test apparatus. The experimental results reveal that a） the nozzle diameter and the inlet conditions exert great influence on the water jet reaction thrust; and b） for L≤4d0, where the nozzle is treated as a thin plate-orifice, the reaction thrust is independent of nozzle length; for L〉4d0, where the nozzle is treated as a long orifice, the reaction thrust can reach maximum under the condition of a certain flow rate. These findings lay a theoretical foundation for the design of nozzles and have significant value, especially for the future development of high-oressure water-let orooulsion technology. 相似文献
5.
李春雨 《福建工程学院学报》2019,(6):569-574
针对现有同轴载气激光熔覆粉末利用率低的不足,设计环式同轴载气激光熔覆头,利用离散单元法对熔覆粉末在粉流道内的运动进行仿真分析,研究熔覆头喷嘴结构参数对粉末汇聚和利用率的影响规律。结果发现,粉流道夹角对粉焦距和汇聚性能影响较大,当夹角为36°时,粉末颗粒分布较为集中,熔覆头的粉末利用率达到最高48.5%。研究成果可为熔覆头结构设计提供理论依据。 相似文献
6.
A parallel dynamic passive valveless micropump was designed, which consists of three layers-valve, diaphragm and electromagnetic coil. The valve was wetly etched in a silicon wafer, the diaphragm was a PDMS （polydimethyl siloxane） film spun on a silicon wafer with embedded permanent magnet posts, and the coil was electroplated on a silicon substrate. Under the actuation of the magnetic field generated by coils, the flexible diaphragm could be displaced upwards and downwards. After analyzing magnetic and mechanical characteristic of the flexible membrane and direction-dependence of the nozzle, a micropump was designed. And the relative length （L/d） of the micropump nozzle was taken 4. A 7 × 7 array of permanent magnetic posts was embedded in the PDMS film. Two diaphragms worked in an anti-step mode, which could relieve the liquid shock and increase the discharge of the micropump. The ANSYS and Matlab were adopted to analyze the actuation effect of the coil and the flow characteristic of the micropump. Results show that when actuated under a 0.3 A, 100 Hz current, the displacement of the diaphragm is more than 30 μm, and the discharge of the micropump is about 6 μL/s. 相似文献
7.
Guang-ming Chen Li-xia Liang Li-ming Tang Xiao-xiao Xu Zhi-jiang Zhu Qi Chen 《浙江大学学报(A卷英文版)》2009,10(11):1678-1682
An adjustable ejector expansion device for a CO2 heat pump water heater （HPWP） is proposed to improve the system performance. It has been designed to investigate experimentally the effects of the motive nozzle throat area of the ejector, entrained flow pressure, back pressure and primary flow pressure on the entrainment ratio. Experiments based on different motive nozzle throat areas were conducted and the results of the prototype ejector using CO2 as working fluid are presented. The results show that an adjustable ejector can achieve high performance and work well in a wide range of working conditions. 相似文献
8.
This paper presents a novel micro fabrication method based on the laminar characteristics of micro-scale flows. Therein the separator and etchant are alternatively arranged in micro channels to form multiple laminar streams, and the etchant is located at the site where the reaction is supposed to occur. This new micro fabrication process can be used for the high aspect ratio etching inside a microchannel on glass substrates. Furthermore, the topography of microstructure patterned by this method can be controlled by changing the flow parameters of the separator and etchant. Experiments on the effects of flow parameters on the aspect ratio, side wall profile and etching rate were carried out on a glass substrate. The effect of flow rates on the etching rate and the micro topography was analyzed. In addition, experiments with dynamical changes of the flow rate ratio of the separator and etchant showed that the verticality of the side walls of microstructures can be significantly improved. The restricted flowing etching technique not only abates the isotropic effect in the traditional wet etching but also significantly reduces the dependence on expensive photolithographic equipment. 相似文献
9.
基于多级油泵的现场要求,提出了集多参量检测与控制为一体的多级油泵测控系统。从阐述多级油泵的结构和工作原理入手,确定了以数字信号处理器TMS320LF2812为控制核心的总体方案,设计了流量、压力等参数的检测电路和IGBT的驱动保护电路,给出了相应的软件。结果表明,该测控系统可以以一定的准确度实现压力、瞬时流量、累积流量的测量,也可对三相异步电动机进行变频控制,从而达到调节异步电动机转速、进而调节多级油泵流量和压力的目的。该系统具有结构紧凑、成本低、工作安全可靠、性能优良等特点。 相似文献
10.
结合国内液氧/煤油发动机的研究,针对2种外环管切向进液流、内管进气流的同轴旋流式喷嘴,以酒精和压缩空气为工质,进行了喷雾流常压燃烧实验研究。使用红外热像仪测量了常压条件下喷雾流燃烧的温度分布,分析了火焰结构,定性研究了喷嘴形式和工况对燃烧性能的影响。 相似文献
11.
高温烟气在实际生产活动以及船舶、航天航空等领域均有大量涉及,而如何对其进行冷却是亟待解决的问题.本文以某实际管道内的高温烟气为研究对象,利用Fluent软件数值仿真不同喷射参数条件下管道内烟气的冷却过程,并对所得仿真结果进行对比分析.仿真结果表明:采用圆周上均匀分布8个喷孔,单个喷孔流量为0.05 kg/s时,可满足烟气冷却要求.基于数值仿真结果,设计了适用于该管道结构的冷却装置.本研究结果对管道内高温烟气的冷却处理具有参考意义,所设计的冷却装置具有实际应用价值. 相似文献
12.
为使大风量、高风速空调箱内的空气流能够迅速地实现均流,开发出了一种草帽型均流板。该均流板能够使空气在仅为0．4～0．6m的距离内将空气由40m／s降低到2．5m／s,并使空气在蒸发器迎风面上均匀分布,以提高蒸发器的换热效果,减小蒸发器结霜的可能性．提高机组的能效比。 相似文献
13.
旋流喷嘴射流宏观及微观特性实验研究 总被引：2，自引：0，他引：2
对旋流喷嘴射流的宏观和微观特性 ,如表面波的发展、射流破碎过程、喷雾锥角、破碎长度等进行了实验研究 ,考察了喷嘴结构、喷射条件、射流介质的物性等对空心旋转液体射流特性的影响 .揭示了旋流喷嘴的射流特性 ,有助于旋流喷嘴的设计、应用及改进 相似文献
14.
15.
Viking Brunell 《Scandinavian Journal of Educational Research》2013,57(4):259-267
The question of what makes a text easy or difficult to comprehend is answered on the basis of an empirical investigation, which draws especially on theories related to text and memory linguistics. Easy and difficult texts, verified empirically, were analyzed on micro‐ and macro‐levels. Certain aspects of syntax, lexicon and information structure were first studied. These were followed by text‐level analyses related to the narrative and structural organization and the propositional structure of the texts. The article gives an account of the parameters that were most clearly associated with level of text comprehension. The results are also discussed in the light of the possible implications for language in the Swedish‐medium instructional materials in Finland. 相似文献
16.
70t底吹氩钢包水模型实验 总被引：1，自引：0，他引：1
针对某钢厂70 t底吹氩钢包进行水模型实验,通过测定不同吹气量下的混匀时间来优化其最佳喷吹位置及示踪剂最佳加入位置;卷渣模拟实验来确定临界卷渣喷吹量。实验研究表明,最佳喷吹位置为原孔及与原孔成180°方向上0.6R处双吹,该喷吹方式下示踪剂最佳加入位置为钢包中心;单吹临界卷渣吹气量为270 L/m in,双吹临界卷渣吹气量为320 L/m in。 相似文献
17.
伍成波 《重庆大学学报(英文版)》2003,2(2)
1. Introduction The bake-out and start-up technologies of aluminum reduction cells is one of the important factors affecting the service life of cells. The service life of cells is of importance to economic benefit in aluminum reduction cells production. Especially for big prebaked cells, the study on bake-out and start-up is even more important. The present methods of bake-out include aluminum fluid bake-out, coke granule bake-out and graphite bake-out [1,2]. The disadvantage of aluminum ba… 相似文献
18.
A mathematic model of two-phase flow and a physical model of two-dimensional (2D) vertical section for the plate-type structured packing Mellapak 250.Y were set up and verified. The models were used to study the influence of packing’s surface microstructure on the continuity of liquid film and the amount of liquid holdup. Simulation results show that the round corner shape and micro wavy structure are favorable in remaining the continuity of liquid film and increasing the amount of liquid holdup. The appropriate liquid flow rate was determined by investigating different liquid loadings to obtain an unbroken liquid film on the packing surface. The pressure difference between inlet and outlet for gas phase allowed gas and liquid to flow countercurrently in a 2D computational domain. The direction change of gas flow occurred near the phase interface area. 相似文献
19.
通过建立塑化流体的流量与成型机过渡区螺杆结构参数的数学模型,从理论上对影响塑化流体流量的过渡区螺杆结构参数进行深入研究,找出了塑化流体流量、逆流、螺杆参数间的关系,得出了过渡区螺杆结构的最佳参数;通过优化过渡区的螺杆参数,增加塑化流体的流量,使薪棒密度增大,达到提升机制木炭的性能和质量的目的. 相似文献
20.
De-sheng WEN Zhi-li WANG Jun GAO Yong ZHANG Shi-jun LV Tetsuhiro TSUKIJI 《浙江大学学报(A卷英文版)》2011,12(4):301-309
The primary focus of this study was to investigate a series of novel motors and pumps, based on a new type of structure called
double-stator. The double-stator structure can be used as pump or motor just based on the application requirements. A certain
amount of pumps or motors can be formed in one shell, and these sub-pumps or sub-motors can work alone or be combined without
influence on each other. So this kind of double-stator pump (motor) is called a multi-pump (multi-motor). Through the analysis
of multifarious connection modes of the double-acting double-stator multi-pumps and multi-motors, the mathematical expressions
of the output flow rate and the rotational speed are acquired. The results indicate that a quantity of different flow rates
can be provided by one fixed-displacement multi-pump under the condition of unalterable driven speed by electromotor. Likewise,
when supplied by settled input flow, without complex variable mechanism, the functions of double-speed, multiple-speed, and
even differential connection can be obtained by employing the use of a double-stator multi-motor. The novel hydraulic transmission
is made of such a double-stator multi-pump and multi-motor, and has broad application prospects. 相似文献