内混式油喷嘴运行临界点的冷态实验研究

内混式介质雾化喷嘴运行时,当运行油压高于某雾化气体压力时,会发生部分油经气孔倒流入气管系统的第一类临界工况;当运行雾化气体高于某油压时,会发生部分雾化气体经油孔倒流入油管系统的第二类临界工况.对某内混式喷嘴采用冷态流量实验研究与数据处理相结合的方法,确定了这两类临界工况,为内混式喷嘴的可靠运行提供了依据.     

内混式介质雾化喷嘴流量特性实验研究

以压缩空气和变压器油为工质对内混式介质雾化油喷嘴的流量特性进行实验研究,并通过逐步回归分析的方法获得了内混式介质雾化喷嘴油、气流量系数与运行及结构参数的实验关系式,可供设计使用部门参考。     

Y型喷嘴油雾两相流中雾化细度的差异性研究

文章分析了Y型油喷嘴混合孔流通道内环状油膜贴壁流及内含大量油滴的类雾状流的特点和从喷口喷出后二次雾化形式及差异;实验测得了单股油雾两相流的中心1／2处及偏中心线1／2处雾化细度SMD的差异值和流量密度分布特性。     

WDH型气泡雾化喷嘴的流量特性研究

WDH型气泡雾化柴油、重油、渣油及奥里油燃烧器已在各行业的工业炉窑上得到了广泛的应用。本文对WDH型气泡雾化喷嘴的流量特性进行了实验研究，此项研究结果对进一步开发WDH型气泡雾化喷嘴的应用领域将发挥重要的作用。     

紧耦合气雾化流场结构突变过程的数值模拟

紧耦合气雾化制粉过程中,当雾化气压超过某一临界值时,直管环缝型喷嘴的气雾化流场结构存在"开涡—闭涡"突变现象,雾化效果随之发生显著改变。该文采用数值模拟方法研究紧耦合喷嘴气体流场中开涡和闭涡结构特征及其突变行为,以及雾化介质类型和喷嘴几何结构参数(喷射顶角、导液管伸出长度和末端直径、环缝宽度)对临界雾化压力Pc的影响。结果表明:当雾化压力P略高于Pc时,马赫盘迅速截断回流区,流场结构由开涡向闭涡突变,并引起喷嘴熔体出口下方抽吸压力Pa骤降,突变前后抽吸压力差ΔPa约为30 kPa;雾化介质类型和喷嘴主要几何结构参数对Pc有显著影响,但对ΔPa无明显影响。     

带钢镀后气雾冷却喷嘴雾化性能的试验研究

气雾冷却是一种适合于带钢镀后冷却的冷却方式。以空气和水为工作介质,对新开发的气水直交型喷嘴的雾化性能进行试验研究,主要测试流量密度分布、雾化角和流量压力特性。试验发现：喷嘴雾化后液滴粒度很小,且对水量变化不敏感;喷嘴的雾化角较小;喷气箱体的压力主要受喷水流量的影响,通过回归分析得到了用于喷箱设计的压力流量关联式。     

"旋转型气-液雾化喷嘴"的雾化角与流量分布特性研究

对“旋转型气-液雾化喷嘴”的雾化角的变化规律进行了研究，主要考虑了喷嘴的结构参数，气液比(ALR)，液体粘度等因素对雾化角的影响。通过实验测量与拟合，最后给出了喷嘴的雾化角的表达式。同时对喷嘴的流量分布特性进行了研究，指出其流强分布为马鞍型分布。     

基于CFD的水雾化锌粉喷嘴性能研究

雾化喷嘴是水力雾化锌粉工艺的关键设备之一,其结构的合理性,直接决定水雾化锌粉工艺的成败。在研发以水为工作介质的高压大流量雾化喷嘴过程中对喷嘴内部的流场进行了全面的CFD分析,研究了喷嘴结构参数锥面间隙和喷射内夹角对其射流性能的影响。研究结果表明:在锥面间隙h=0.3 mm、射出内角α=60°条件下,喷嘴综合性能最优。基于本次研究的新型喷嘴设计合理,能满足水雾化锌粉工艺要求。     

简讯

由上海交通大学与上海玻璃机模厂共同研制的BRX型玻璃窑炉燃油喷嘴及其装置已于1986年12月30日在上海通过鉴定。BRX型喷嘴利用表压力为0.28兆帕(2.8kg/cm~2)、流量为燃料理论空气量2%左右的空气对燃油进行雾化,在结构设计上使得空气的旋转方向与燃油的旋转方向相反,并使空气进行二次临界膨胀,从而保证了燃油的良好雾化以及沿周向均匀的分布。装置的作用是保证正常地向喷嘴供应燃油和雾化空气,并按需要,定时切换两     

低压空气雾化烧嘴雾化机理分析及最优结构参数研究

低压空气雾化烧嘴雾化机理分析及最优结构参数研究马其良，张松寿，刘伟军，陆胜年华东工业大学动力学院燃烧室（邮编：上海２０００９３）低压空气事化烧嘴是以低压空气为雾化介质的油喷嘴。自５０年代从国外引进以来，经不断研究改进，先后开发出Ｃ型、Ｋ型、Ｒ型、ＲＫ...     

Influence of gas flow on performance of “Confined” atomization nozzles

Supersonic gas jets in “confined” nozzles were studied by Schlieren photography in blank atomizing tests (i.e., no liquid present). Tests in nitrogen at 1.56 MPa pressure showed that changes in the geometry of a nozzle altered the wave pattern and the height of the supersonic region in the jet. In particular, the protrusion height of the metal delivery tube (above the gas exit) had a profound influence. An expansion wave formed at the tip of the nozzle when the protrusion height was too high, and the jet became subsonic in a short distance. Longer supersonic wave patterns were observed at lower protrusion heights following the appearance of a shock wave at the tip of the nozzle. These results correlated well with the atomizing performance of the same nozzles determined previously. The nozzles which had long supersonic flow regions corresponded to those which produced fine powders, and short supersonic regions were associated with reduced efficiency in performance. This indicated that the preservation of high velocities in the gas was of primary importance for effective liquid breakup in atomization. A procedure (based on the characteristics solution of supersonic flow) was developed for assessing flow conditions in atomizing nozzles and for calculating the optimum height of the delivery tube for a given geometry to obtain the longest supersonic jet.     

燃油锅炉燃烧器雾化原理分析及改进对策

由于锅炉燃料的改变,锅炉油喷嘴不能适应新情况,经常出现燃烧方面的故障。本文通过对燃油雾化原理的分析,结合两种雾化器的性能比较,提出了雾化器更新方案,彻底解决了锅炉燃烧方面存在问题,保证了锅炉的稳定运行。     

超声波重油喷嘴雾化特性的研究

介绍了一种新型流体动力式超声波重油雾化喷嘴。为了研究其雾化特性,以压缩空气和水为介质,利用激光粒度分析仪对超声波重油雾化喷嘴的雾化特性进行了详细的研究,分析了该型喷嘴的工作特点,研究了不同供气压力、供水压力和气液比(ALR)对喷嘴雾化性能的影响,同时也分析了粒径沿程变化情况。研究表明:流体动力式超声波重油雾化喷嘴雾化索太尔平均粒径非常小,为10～20μm,具有较好的应用前景。     

攀钢板坯连铸机二冷区喷嘴特性测试

对连铸二冷区喷嘴的冷态特性进行了研究。测定了不同喷水条件下喷嘴的压力一流量关系,喷水密度分布以及喷射角和喷雾粒度分布。分析了国内外喷嘴的特性曲线,为国内厂家生产喷嘴提供了更为合理的参数。     

An experimental study on the atomization characteristics of the nozzle for the after-pot cooling of galvanized steel sheets

Air-atomized fog cooling is particularly suitable for the after-pot cooling of galvanized steel strips.With air and water serving as working media,an experimental study was conducted on the atomization characteristics of a newly-developed cross-flow type of fog nozzles.The water flux distribution,spray angle and pressure of water and air were measured.The results show that the water droplet size was small and insensitive to the water flow rate.The spray angle was small and the water flow rate slightly affected the air pressure in the chamber.An empirical correlation between the pressure in the chamber and the gas flow rate was obtained for the purpose of equipment design.     

钢包底吹氩均混时间及临界流量水模型实验

针对钢包底吹氩工艺,通过改变透气砖数量、单透气砖吹气位置、双透气砖夹角、喷吹气体流量、渣厚等参数,对钢包的均混时间进行了水模型实验研究.提出临界流量的概念,发现吹气量超过临界流量后均混时间明显减小.结果表明:单透气砖喷吹时,相同吹气量下偏心喷吹时的均混时间比中心喷吹时短,临界流量小;双透气砖喷吹时,透气砖夹角越大,均混时间越短,临界流量越小.     

Size and Velocity Characteristics of Droplets Generated by Thin Steel Slab Continuous Casting Secondary Cooling Air-Mist Nozzles

Direct spray impingement of high temperature surfaces, 1473 K to 973 K (1200 °C to 700 °C), plays a critical role in the secondary cooling of continuously cast thin steel slabs. It is known that the spray parameters affecting the local heat flux are the water impact flux w as well as the droplet velocity and size. However, few works have been done to characterize the last two parameters in the case of dense mists (i.e., mists with w in the range of 2 to 90 L/m²s). This makes it difficult to rationalize how the nozzle type and its operating conditions must be selected to control the cooling process. In the present study, particle/droplet image analysis was used to determine the droplet size and velocity distributions simultaneously at various locations along the major axis of the mist cross section at a distance where the steel strand would stand. The measurements were carried out at room temperature for two standard commercial air-assisted nozzles of fan-discharge type operating over a broad range of conditions of practical interest. To achieve statistically meaningful samples, at least 6000 drops were analyzed at each location. Measuring the droplet size revealed that the number and volume frequency distributions were fitted satisfactorily by the respective log-normal and Nukiyama–Tanasawa distributions. The correlation of the parameters of the distribution functions with the water- and air-nozzle pressures allowed for reasonable estimation of the mean values of the size of the droplets generated. The ensemble of measurements across the mist axis showed that the relationship between the droplet velocity and the diameter exhibited a weak positive correlation. Additionally, increasing the water flow rate at constant air pressure caused a decrease in the proportion of the water volume made of finer droplets, whereas the volume proportion of faster droplets augmented until the water flow reached a certain value, after which it decreased. Diminishing the air-to-water flow rates ratio, particularly below 10, resulted in mists of bigger and slower droplets with low impinging Weber numbers. However, increasing the air pressure maintaining a constant water flow rate caused a greater proportion of finer and faster drops with Weber numbers greater than 80, which suggests an increased probability of wet drop contact with a hot surface that would intensify heat extraction.     

铁锰无磁合金粉的水雾化法生产工艺研究

采用水雾化法制备铁锰无磁合金粉末, 分析了合金粉末含锰质量分数和雾化工艺对铁锰合金粉末性能的影响规律。结果表明: 水雾化法生产铁锰无磁合金粉的方案可行, 但锰质量分数不宜低于24%;在实验工况条件下, 雾化压力对松装密度的影响可以忽略不计, 雾化压力提高使产品流动性变差, 以15 MPa雾化压力进行生产时, 产品工艺性能(松装密度、流动性) 最好; 雾化压力的提高有助于提高产品烧结密度, 在满足产品流动性要求的前提下, 可以考虑通过提高雾化压力来提高产品烧结密度。     

急冷水雾化工艺对金属粉末性能的影响

为了开发制粉新工艺和制备用于MIM的微细合金粉末，设计了组合雾化。在常规水雾化喷嘴的下方附加了冷却喷嘴，并以锡青铜粉为试验对象，研究了工艺条件对水雾化金属粉末性能的影响。结果表明，使用同样的设备，急冷组合雾化与单一雾化相比，能使粉末更加细化。同时，由于粉末冷却速度的提高，使粉末氧含量得到降低，颗粒外形变得更加不规则。