气液双介质喷嘴雾化特性的影响因素研究

目的 气液双介质喷嘴的应用是烟叶加料工艺的关键因素之一，通过采用现有的模拟手段实现加料过程的高精化，为优化实验奠定基础。方法 文中以外混式双介质喷嘴为研究对象，通过构建基于DPM的数值模型，研究不同蒸汽入口压力与针阀位置对喷嘴雾化的气动性能与粒径特性的影响规律。结果 研究表明，喷嘴出口通流面积越大，气流高速区离喷嘴越近，但蒸汽与料液的速度最大值并未有较大变化，此时液滴喷射距离由远变近，喷射半角由小变大。随着蒸汽压力的增大，气流速度以及高速区长度变大，蒸汽压力为0.1 MPa时，气流速度的最大值与蒸汽压力为0.4 MPa时的相差近25%;不同压力下喷射角变化范围较小，为21.5°~23.5°;除此之外，喷雾束变集中，定向性变好，有助于控制其在烟叶表面喷射的均匀性。结论 对于较近的烟叶墙，采用较大流通截面积的喷嘴结构有利于均匀地覆盖烟叶墙，相反，对于较远的烟叶墙，则适合采用较小流通截面积的结构。适当地提高压力有利于提高料液喷洒的均匀性，减少料液的浪费，提高烟丝制备的工艺水平。

Factors Affecting the Atomization Characteristics of Vapor-liquidDual-medium Nozzles

The application of vapor-liquid dual-medium nozzle is a key factor in the tobacco feeding process. To achieve the high precision of the feeding process, it is necessary to use the existing simulation means to lay a foundation for optimizing the preliminary work of the experiment. In this work, the external mixed dual-medium nozzle was taken as the research object. Through the construction of a numerical model based on DPM, the effects of different steam inlet pressure and needle valve position on the aerodynamic performance and particle size characteristics of the nozzle atomization were studied. The results showed that the larger the flow area at the outlet of the nozzle, the closer the high-speed area of the gas flow was to the nozzle, but the maximum velocity of steam and liquid did not change greatly. At this time, the droplet injection distance changed from far to near, and the injection half angle changed from small to large. With the increase of steam pressure, the airflow velocity and the length of the high speed zone became larger. When the steam pressure was 0.1 MPa, the difference between the maximum airflow velocity and that at steam pressure of 0.4 MPa was nearly 25%. Under different pressures, the range of injection angle was small, ranging from 21.5° to 23.5°. Besides, the concentration of the spray was more concentrated, the directivity was better, and the number distribution of droplets was relatively uniform. It was favorable to control the uniformity of the spray on the surface of the tobacco leaves. For the closer tobacco wall, the nozzle structure with larger circulation cross-sectional area is conducive to evenly cover the tobacco wall. On the contrary, for the farther tobacco wall, the structure with smaller circulation cross-sectional area is suitable. Proper increase of pressure is beneficial to improve the uniformity of liquid spraying, reduce waste of liquid and improve the technological level of tobacco cutting.