共查询到18条相似文献,搜索用时 125 毫秒
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根据流体力学原理,对旋涡环缝雾化器设计参数进行了分析研究,提出了旋涡环缝雾化器设计参数的定性解析和定量描述;导出了气流雾化介质在导流管内流动时不产生紊流的管径计算式以及雾化器环缝出口尺寸取得极大值和求取环缝出口截面积的解析表达式;建立了雾化顶角设计计算的函数关系式;指出了保障环缝同心度的重要性.为旋涡环缝雾化器的设计提... 相似文献
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气流出口截面恒定的雾化器设计 总被引:1,自引:0,他引:1
刘福平 《金属材料与冶金工程》2007,35(4):40-42
利用流体力学理论,对雾化器产生的气流出口流速及质量流率进行了分析.当雾化器出口截面恒定时,建立了气流出口流速呈极大值所需的雾化压力的数学表达式;导出了在雾化气流量恒定条件下,气流出口流速呈极大值时出口截面积与雾化器腔体截面积的函数关系式. 相似文献
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金属3D打印专用球形粉末普遍采用气雾化法制备,无坩埚电极感应气雾化技术(EIGA)制备的金属粉末具有氧增量低、细粉收得率较高、球形度高、流动性好等优点。实验对雾化喷嘴导流管底端的气流场进行了数值模拟,研究导流管长度和雾化压力对气体回流的影响,并通过雾化实验对模拟结果进行了验证。结果表明:导流管长度存在一临界值,当长度低于临界值时,雾化喷嘴环缝外侧气体的流速高于内侧气体的流速,气体易回流进入导流管内部,导致较多缺陷粉产生;长度高于临界值时,环缝内侧气体的流速高于外侧气体的流速,气体回流现象消失,缺陷粉数量大幅减少。雾化压力主要影响粉末的粒径,雾化压力越大,粉末粒径越小。 相似文献
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许多研究认为,雾化气体流动场的特性将影响熔融金属的破碎方式及液态颗粒尺寸和质量的分布,是决定产品显微组织与冶金质量的重要因素之一。该特性在很大程度上依赖于雾化喷嘴的结构,同时也跟工艺因素有关。本试验在不同的雾化状态下测量了导液管末端的压力值,雾化气体锥内轴向和径向的气流速度等,从而确认试验喷嘴的气体流动场特性及其影响因素。 相似文献
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在气体雾化过程中,采用限制式喷嘴以实现超音速气流雾化,能有效细化粉末颗粒。在一定条件下,提高气/液流量比是获得较高细粉收得率的有效途径。 相似文献
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文章研究了气体压力大小在雾化粉末工艺过程中的影响。结果表明,在限制式的喷嘴结构中,当熔体温度、气流喷射角度确定的条件下,气体压力较小,雾化颗粒不能形成,熔体会在导管中凝固或形成倒锥形的粘结块;随着气体压力的增加,粉末球化程度增大,平均颗粒减小。 相似文献
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分析了一种环缝气流冲击雾化制粉喷嘴的结构和工作原理, 并对该雾化喷嘴模型进行了流场分布数值仿真, 研究了不同进气压力和窄缝倾角对流场速度分布的影响。研究结果表明, 从进气管入口到气流冲击雾化喷嘴出口, 加速气流速度保持最大值不变, 在距进气管入口中心线上80 mm位置之后逐渐减小; 随着进气压力的增加, 气流冲击雾化喷嘴出口速度表现出明显的增加趋势, 且仿真结果与理论计算结果误差在10%范围以内。随着窄缝倾角的增加, 负压涡流逐步向进粉管靠近, 回流区、分离区和混合区的最大速度值表现出单调增加的变化规律; 综合考虑气流冲击效果和喷射速度, 确定最优的窄缝倾角50°~60°。 相似文献
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A syringe jet injector is a device designed to administer a drug quickly and painlessly through the skin. Though syringe jet injectors have been in use for almost 50 years, current designs still suffer from inconsistent performance. To better understand the fluid mechanics of jet injection and gain insight into how the design might influence performance, two theoretical analyses to determine the fluid pressure profile at the exit orifice were conducted. The first was a continuum analysis assuming static incompressibility. Results demonstrated that the maximum jet pressure was highly sensitive to the spring constant, initial piston velocity, and piston cross-sectional area while the time to achieve the maximum pressure was most sensitive to the injection chamber length, initial piston velocity, bulk modulus of the injectant, and the piston cross-sectional area. The second analysis was a shock wave analysis. Results demonstrated a stepwise pressure-time plot that was similar in magnitude to that for the continuum analysis assuming static incompressibility. Results from these two investigations are useful for design modification of the jet injector to achieve desired pressure-time profiles at the orifice. Control of pressure-time profiles may help to achieve a more consistent and effective injection process. 相似文献
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A. Ünal 《Metallurgical and Materials Transactions B》1989,20(6):833-843
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. 相似文献
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CharacteristicsofNitrogenJetandItsEffectontheBathinSlagSplashingYangWenyuan①,ZhengCongjie①,BaiRuiguo②,FuZhenrong②,ZhangXingli... 相似文献