共查询到18条相似文献,搜索用时 125 毫秒
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喷嘴雾化特性实验研究 总被引:56,自引:0,他引:56
液体雾化是当前两相流研究中非常重要的课题,在农业、能源以及环境工程中具有广泛的应用价值,进行深入系统的研究具有重要意义。本文以空气、水为工质,使用马尔文粒度仪对单相和两相雾化器喷嘴的雾化特性进行了比较实验研究。测量了不同压力配比条件下液体雾化粒子的粒径分布,详细讨论了压力对于喷嘴雾化效果的影响。同时得出了两相流量与压力之间的变化规律。 相似文献
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煤油氧气脉冲爆震火箭发动机爆震特性 总被引:1,自引:0,他引:1
脉冲爆震火箭发动机(PDRE)是一种利用脉冲式爆震波产生高温、高压燃气发出的冲量来产生推力的推进系统.与常规液体火箭发动机相比,脉冲爆震火箭发动机具有更高的性能,并且结构更简单.本文以航空煤油为燃料、氧气为氧化剂、压缩氮气为隔离气体,并利用电磁阀控制燃料、氧化剂和隔离气体的间歇式供给.利用低的点火能量(50mJ),在内径50mm,长度1.1m的爆震管内进行了大量的多循环爆震试验,研究煤油氧气电磁阀脉冲爆震火箭发动机的爆震波特性.研究结果为进一步研究气液两相多次爆震燃烧机理提供了依据,为研制工程应用的PDRE提供理论和实践基础. 相似文献
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煤油/空气脉冲爆震发动机激波反射起爆研究 总被引:2,自引:0,他引:2
为了研究煤油/空气脉冲爆震发动机爆震室内激波遇到障碍物发生反射促使PDE通常完成爆燃向爆震转变的起爆技术,设计加工了环型孔板和双半V型楔面体,并安装在内径100 mm的爆震管内,进行了多循环爆震试验,成功实现了煤油/空气脉冲爆震发动机工作频率30 Hz稳定工作,获得稳定传播的爆震波.研究结果表明:在爆震室内安装合理结构的障碍物能够有效提高激波反射,缩短爆燃向爆震转变的距离(时间),成功获得稳定传播的爆震波.研究结果为优化设计煤油/空气脉冲爆震发动机原理样机提供了初步理论基础. 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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电极感应熔化气雾化(electrode induction melting gas atomization, EIGA)是一种制备超洁净无夹杂物的先进制粉技术,本文以粉末高温合金的氩气雾化过程为研究示例,对现有用于实际生产的国内某厂家提供的EIGA用非限制式喷嘴进行建模,采用商用计算流体力学软件FLUENT,分布采用欧拉-欧拉VOF(volume of fluid)多相流方法与欧拉-拉格朗日DPM (discrete phase model)离散相方法,对非限制式环缝喷嘴主雾化与二次雾化过程进行了数值模拟.通过对主雾化过程中多相流大涡模拟速度流场,主雾化过程中不同阶段高温熔体云图模拟以及二次雾化过程中TAB (Taylor analogy breakup)模型速度流场及TAB模型粒度分布的模拟研究,实现了对EIGA制粉技术中非限制式喷嘴雾化过程的全过程模拟,并预测了雾化后的粉末粒度分布.在此基础上,采用本文模拟使用的非限制式环缝喷嘴,设定与模拟条件一致(进气压力4 MPa,液流直径约4 mm)的实验条件,制备的粉末大部分颗粒的直径大小在100μm左右,该实验结果与模拟得到的粉末直径D50=100μm大小一致,进一步验证了模拟数据的合理性.该方法也适用于非限制式喷嘴里,其他金属或合金的雾化过的模拟研究. 相似文献
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Arthur H. Lefebvre 《Particle & Particle Systems Characterization》1996,13(3):205-216
The results of recent researches on twin-fluid atomization are briefly reviewed, with particular emphasis on the effects of air and liquid properties on mean drop size. It is stressed that no single equation for the mean drop sizes produced in twin-fluid atomization can satisfactorily correlate all the experimental data from any given atomizer. This is because for all types of atomizers the mechanism of liquid breakup changes from one basic mode to another with changes in atomizer operating conditions and/or liquid properties. These different modes of atomization exhibit different dependencies on atomizer dimensions and various physical properties such as liquid viscosity and air density. Equations for estimating the mean drop sizes produced in the various modes of twin-fluid atomization are presented and discussed. 相似文献
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Effervescent atomization is one of the twin-fluid atomization methods while it has better performance in terms of smaller
drop sizes and/or lower injection pressures. In order to investigate the effects of the internal flow patterns on droplet
characteristics, a new kind of effervescent atomizer was designed and manufactured. The bubble forming process was visualized
with a high-speed camera, while the droplet size was characterized with a LDV/PDA system. The experimental results show that
there are three regimes of the two-phase flows inside the discharge orifice, one is bubbly flow, another is annular flow while
the other is the intermittent flow. The flow patterns transfered from bubbly flow to intermittent flow and then to annular
flow with decreasing of the water flow rate. In addition, with increasing of the working pressure or decreasing of the water
flow rate, the SMD (Sauter mean diameter) of the droplets decreased and the axial mean velocity increased. 相似文献
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Kiran. A. Ramisetty Aniruddha. B. Pandit Parag. R. Gogate 《Ultrasonics sonochemistry》2013,20(1):254-264
The present work deals with measurements of the droplet size distribution in an ultrasonic atomizer using photographic analysis with an objective of understanding the effect of different equipment parameters such as the operating frequency, power dissipation and the operating parameters such as the flow rate and liquid properties on the droplet size distribution. Mechanistic details about the atomization phenomena have also been established using photographic analysis based on the capture of the growth of the instability and sudden ejection of droplets with high velocity. Velocity of these droplets has been measured by capturing the motion of droplets as streaks. It has been observed that the droplet size decreases with an increase in the frequency of atomizer. Droplet size distribution was found to change from the narrow to wider range with an increase in the intensity of ultrasound. The drop size was found to decrease with an increase in the fluid viscosity. The current work has clearly highlighted the approach for the selection of operating parameters for achieving a desired droplet size distribution using ultrasonic atomization and has also established the controlling mechanisms for the formation of droplet. An empirical correlation for the prediction of the droplet size has been developed based on the liquid and equipment operating properties. 相似文献
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M. Reza Soltani Kaveh Ghorbanian Mehdi Ashjaee Mohammad R. Morad 《Particle & Particle Systems Characterization》2005,22(3):192-206
Experiments are performed to investigate the atomization characteristics of mixed‐interaction regions of sprays of two swirl injectors installed side by side. Both droplet size and velocity distributions on a plane perpendicular to the axes of the injectors are measured using a PDA system. As a result of the interaction phenomenon, a region of secondary atomization is identified that differs significantly from the hollow region spray of a single swirl injector. A neural network algorithm is used to reconstruct the entire spray field for both droplet size and velocity distribution in extrapolation regimes for injector spacing as well as three dimensional spatial coordinates. Excellent agreement between the predicted values and the measurements is obtained. It is observed that points on the extrapolation regime of the neural network can be predicted with an accuracy of 93 % using a training data set with less than 50 % of the number of data points to be predicted. The results indicate the capability of performing design‐ and optimization studies for pressure‐swirl injectors, with sufficient accuracy, by applying a modest amount of data in conjunction with an overall optimized value for the width of the probability. 相似文献
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F. Jouot G. Dupré A. Quilgars I. Gökalp E. Cliquet 《Proceedings of the Combustion Institute》2011,33(2):2235-2241
Direct initiation and propagation of detonation through a cryogenic two-phase flow constituted by liquid oxygen droplets in gaseous hydrogen at 100 K are experimentally investigated. The influence of droplet size distribution is characterized in a cryogenic gaseous helium and liquid oxygen two-phase flow. Droplet sizing and detonation experiments are conducted by varying different parameters: distance from the injector, helium and hydrogen mass flow rates, global equivalence ratio and addition of gaseous nitrogen. Droplet size distributions reveal quick vaporization of the smallest droplets of the cryogenic jet. Results in terms of wave velocity, pressure, and detonation cells show that a detonation wave can be directly initiated, with a propagation wave velocity of 20% higher than the Chapman–Jouguet value. Cell size measurements show that the mixture sensitivity is not affected by the presence of droplets. Addition of gaseous nitrogen reduces only slightly the peak pressure, but the detonation velocity is reduced by about 30%. 相似文献
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Ultrasonic atomization: effect of liquid phase properties 总被引:4,自引:0,他引:4
Experiments have been conducted to understand the mechanism by which the ultrasonic vibration at the gas liquid interface causes the atomization of liquid. For this purpose, aqueous solutions having different viscosities and liquids showing Newtonian (aqueous solution of glycerin) and non-Newtonian behavior (aqueous solution of sodium salt of carboxy methyl cellulose) were employed. It has been found that the average droplet size produced by the pseudo-plastic liquid is less than that produced by the viscous Newtonian liquid having viscosity equal to zero-shear rate viscosity of the shear thinning liquid. The droplet size was found to increase initially with an increase in the viscosity up to a certain threshold viscosity after which the droplet size was found to decrease again. Also droplet size distribution is found to be more compact (uniform sizes) with an increasing viscosity of the atomizing liquid. The presence of the cavitation and its effect on the atomization has been semi quantitatively confirmed using energy balance and by the measurement of the droplet ejection velocities and validated on the basis of the decomposition of the aqueous KI solution. A correlation has been proposed for the prediction of droplet size for aqueous Newtonian fluids and fluids showing non-Newtonian behavior based on the dimensionless numbers incorporating the operating parameters of the ultrasonic atomizer and the liquid phase physico-chemical properties. 相似文献