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为合理设计微小尺度液体燃料荷电喷雾燃烧器,开展了不同运行参数下喷雾特性的PDA(相位多普勒粒子分析仪)实验研究.实验段采用由喷嘴电极-环形电极-收集网格形成的组合电极结构,以乙醇为燃料,控制不同的喷嘴电压、环形电极电压、流量、收集网格位置等参数,测试了不同条件下的喷雾粒径、轴向速度、轴向脉动速度.在本文实验工况下发现:喷嘴电极电压的增加,粒径和速度减小.环形电极可显著减小喷雾粒径和速度。在环形电极感应荷电的作用下,粒径随着环形电极电压增加而增大。流量越小,粒径、速度越小,喷雾更稳定.增大收集网格到喷嘴出口距离,由于液滴蒸发的作用会使液滴粒径变小,在液滴粒径变小和黏滞力的双重作用下液滴轴向速度减小。 相似文献
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双路离心式喷嘴的实验与数值模拟 总被引:1,自引:0,他引:1
《工程热物理学报》2010,(10)
通过实验与数值模拟方法开展了双路离心式喷嘴的研究。实验测量了喷嘴主、副油路在不同压力下的雾化锥角与流量特性,拍摄了喷嘴在典型工况下的喷雾场照片。数值模拟采用VOF(Volume-of-Fluid)两相流模型来模拟喷嘴内气液两相流流动,较好地模拟出喷嘴内的空气涡与喷雾锥角,所得到喷雾锥角与实验结果吻合较好。通过实验与数值模拟相结合的方法验证了双路离心式喷嘴的雾化性能,从而为双路离心喷嘴的设计和性能预测提供了理论基础。 相似文献
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相变喷雾冷却具有很高的换热效率和临界热流密度,为了获得大冷量相变喷雾冷却特性,文中设计并搭建了开式喷雾冷却性能实验台,采用R22制冷剂开展了大热流密度喷雾冷却特性的实验研究,详细研究了不同喷嘴入口压力、不同喷雾高度以及不同加热功率下R22的喷雾相变冷却效果。实验结果的分析表明:采用R22时最高热流密度可达到150W.cm-2,其对应的被冷却表面温度为-29.0℃,具有高热流密度及低冷却表面温度的显著特点;实验还从一定程度上揭示了喷嘴高度和喷嘴入口压力对R22喷雾冷却效果的影响。 相似文献
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石油、化工等过程工业中,由于压力容器或者管道破裂而容易引发高压危险化学品泄漏形成闪蒸喷雾。掌握这类闪蒸喷雾动力学特性对事故危害的风险评估具有重要意义。本文通过开源库OpenFOAM及网格局部加密技术对异戊烷闪蒸喷雾进行了数值仿真研究。不同喷雾初始压力和过热温度下模拟喷雾形态结果、以及液滴粒径与速度分布,均与高速摄像机拍摄的喷雾图像及相位多普勒粒子分析仪(PDPA)测得的粒径、速度数据吻合良好。初始喷雾压力和温度增加时,异戊烷闪蒸喷雾气化成核强化,使喷嘴出口处雾化破碎程度与径向膨胀更为剧烈,出口锥角扩大,同时成核均匀度增加,液滴SMD降低,喷雾速度增加。但是由于轴向动量减弱,液滴相贯穿长度降低。 相似文献
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一种新型喷嘴的提出及流量特性的研究 总被引:6,自引:0,他引:6
本文在对各种气动喷嘴及其雾化机理分析基础上提出了一种新型的气动雾化喷嘴-"旋转型气-液雾化喷嘴"。在此喷嘴中,油与气分别从不同的槽道切向进入混合室,且油与气一一对应,油与气互相混合、旋转后从喷口喷出。其气液比在热态实验时为4%-6%(用压缩空气雾化),雾化状态良好。本文中对其流量系数及雾化角进行了系统的研究。主要考虑了喷嘴的结构参数,气液比(ALR),液体粘度等因素对流量系数的影响。通过实验测量与拟合,最后得到了喷嘴的流量系数和雾化角的表达式,可以用来指导喷嘴的设计。 相似文献
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Daylight visible fluorescent dye (10% v/v) mixed with water was aerially applied on mature field cotton with electrostatic and rotary atomizer nozzles. The spray rates for the electrostatic and rotary atomizer nozzles were 9.4 and 28 L/ha, respectively. Images of spray droplets on cotton leaves were digitally analyzed with ImageJ software. Charged spray cloud increased deposition nearly two to three times on adaxial and abaxial surfaces, respectively, of top canopy leaves compared to uncharged spray. Canopy penetration of the spray into the lower layers of the plant foliage was unaffected by spray application method. 相似文献
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大流量时多股射流静电雾化研究 总被引:2,自引:0,他引:2
为了使静电雾化在大流量时能够应用,本文研究了具有多股射流的某些喷咀。试验表明:多股射流中的每股射流仍然是圆锥体一射流模式,但是具有不稳定性。由此引起了PDA(相位粒度分析仪)测量结果的畸变。同时试验还揭示,每股射流及其雾化依赖于喷咀不同部位的局部主要参数,使得均匀性受到影响。基于稳定性和均匀性之间很强的相互作用,本文提出了增加稳定性及改善均匀性的一些措施。 相似文献
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An infrared thermography-based technique for the characterization and visualization of liquid sprays was developed. The technique was tested on two atomizers: a high-speed rotary bell atomizer and a high volume low pressure air-assisted atomizer. The technique uses an infrared thermography-based measurement in which a uniformly heated background acts as a thermal radiation source, and an infrared camera as the receiver. The infrared energy emitted by the radiation source in traveling through the spray is attenuated by the presence of the droplets inside the spray. The infrared intensity is captured by the receiver showing the attenuation in the image as a result of the presence of the spray. The captured thermal image is used to study detailed macroscopic features of the spray flow field and the evolution of the paint droplets as they are transferred from the applicator to the target surface. 相似文献
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Franois Lacas Philippe Versaevel Philippe Scouflaire Grard Coeur-Joly 《Particle & Particle Systems Characterization》1994,11(2):166-171
Although common atomizing systems efficiently produce sprays, a range of droplet sizes is generally obtained and the distribution is often difficult to control in terms of liquid or gaseous flow rates. It is shown that an alternative system, based on ultrasonic surface instabilities, is well suited for experimental applications where all parameters have to be controlled. Technological aspects of ultrasonic atomization are described and the droplet spray produced by an ultrasonic atomizer is characterized experimentally. 相似文献
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Comparative study on structural and optical properties of CdS films fabricated by three different low-cost techniques 总被引:1,自引:0,他引:1
Highly crystalline and transparent cadmium sulphide films were fabricated at relatively low temperature by employing an inexpensive, simplified spray technique using perfume atomizer (generally used for cosmetics). The structural, surface morphological and optical properties of the films were studied and compared with that prepared by conventional spray pyrolysis using air as carrier gas and chemical bath deposition. The films deposited by the simplified spray have preferred orientation along (1 0 1) plane. The lattice parameters were calculated as a = 4.138 Å and c = 6.718 Å which are well agreed with that obtained from the other two techniques and also with the standard data. The optical transmittance in the visible range and the optical band gap were found as 85% and 2.43 eV, respectively. The structural and optical properties of the films fabricated by the simplified spray are found to be desirable for opto-electronic applications. 相似文献
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Joachim Domnick Vitus Dorfner Franz Durst Masami Yamashita 《Particle & Particle Systems Characterization》1994,11(1):91-100
The results of comparative measurements of three different phase-Doppler systems applied to a steady-state water spray are discussed. The three receiving systems, i. e. DANTEC 57X receiving optics with covariance processor, an AEROMETRICS fibre-based receiver with DSA processor and standard INVENT phase-Doppler extension, were used with a 2-D fibre-optics-based transmitting system. A constant scattering angle of 70° was chosen, which is near the Brewster angle for water. Measurements were taken in the spray cone of hollow-cone pressure atomizer at two different axial distances from the nozzle. Local size distributions, size/velocity correlations and the mean diameters D10 and D32 were compared. The results indicate very good agreement between the different systems, especially with respect to the mean diameters. Larger scatter of the results occurs for the measured volume flow rates, but the calculated mean volume flow rates coincide fairly well with the nominal flow rate of the atomizer. 相似文献
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Charge injection atomizers are energy efficient devices that can be used in order to promote the atomization of dielectric liquids, and a potential application of such devices is fine spray delivery in small internal combustion engines. The operation of a pulsed charge injection atomization system operating at practical engine frequencies under a high voltage pulse train has not been well recorded in the literature. This initial investigation defines the electrical and transient global atomization performance of a charge injection atomizer operating under a steady flow regime, but with a typical high voltage pulse train. Results show that voltage-current characteristics follow similar trends to that of a steady flow, steady voltage system, and observation of the data also reveals that output current waveforms depend on the input pulse train frequency. No degradation in charging efficiency was observed at higher frequencies, which suggests that a charge injection atomizer can operate efficiently at practical engine speeds. Photographs also confirmed the high voltage pulse train injects charge that produces sections of primary atomization on the continuous liquid jet. 相似文献