稳态烟雾机烟化管结构参数对烟化效果的影响

Effect of structure parameters of exhausted tube in steady fogger on thermal atomizing effect of hot fogging concentrate

以稳态燃烧器为热动力的车载式烟雾机针对农林业病虫害防治具有防治效率高、用药量少、防治成本低等突出优点，烟化管结构参数是影响油溶剂农药能否有效烟化的关键因素。该文设定3种药喷头类型、6个喷头放置位置、3种喷头结构参数以及3个不同直径的双层喷管，分别进行烟化效果试验及分析。结果表明环形喷头烟化效果最好，圆锥形喷头和圆柱形实心锥喷头则出现喷管出口滴液及烟雾中存在明火等烟化不良问题，圆锥形喷头烟化效果好于圆柱形喷头；热雾剂在Φ70 mm喷管内能完全烟化，烟雾雾滴均匀细小，而Φ90和Φ110 mm 2种喷管则会产生较小烟雾和较大雾滴2个分布区，烟化效果不良；环形喷头置于喷管内距喷管喷口250～350 mm的范围内，可获得较好的烟化效果；环形喷头的结构参数如药液出口方向、喷药孔径和孔数对热雾剂的烟化效果影响非常小，均能使热雾剂得到完全烟化。说明药喷头类型和喷管直径是影响稳态燃烧烟雾机烟化效果的关键因素，喷头放置位置是影响的主要因素，而环形喷头结构参数是影响的次要因素。

Features of a truck-mounted fogger powered with a steady combustor are high efficiency, low usage, and low cost in control of forestry pest insects and diseases. The structure parameters of its exhausted tube are the key factors to affect oil solvent insecticide to atomize thermodynamically. We studied 3 types of atomizers：ring atomizer, coniform atomizer and column atomizer; 6 location points for the ring atomizer placed inner of the exhausted tube from 250 to 500 mm away from the exit of the exhausted tube;3 structure parameters of a ring atomizer as jet flow direction of the orifices, orifice number and diameter; 3 jet flow directions as parallel to airflow, to center of pesticide ring and at 45° to airflow direction;3 different diameters of exhausted-tubes asΦ70,Φ90, andΦ110 mm, which the experiment for atomizing effect was done respectively. The results showed that the ring atomizer was most effective in thermal atomizing;there were the defect phenomena with a coniform atomizer or a column atomizer, such as dropping liquid at the exit of the exhaust tube and combusting flame in the fog. However, the atomizing effect with the coniform atomizer was better than that of the column atomizer. The thermal fogging concentrate can atomize completely to uniform, fine droplets whose size distribution was in a narrow range of 4-6μm, when the ring atomizer was positioned inner aΦ70 mm exhaust tube and in the range of 250-350 mm away from the exit of the exhaust tube. With theΦ90 mm orΦ110 mm exhausted tube, there were two droplet distribution regions：4-7μm for the fine droplet group whose volume ratio to total droplet volume was less than 16%, and 7-226 μm for the coarse droplet group,. The vast majority of coarse droplets could not be completely atomized thermodynamically. The relative span of droplet was only 0.18μm for theΦ70 mm exhaust tube, but were much higher （2.48 and 2.65μm） for the Φ90 and Φ110 mm exhaust tubes respectively. The parameters for a ring atomizer, such as the diameter, number and jet flow direction of the orifices basically did not affect the thermal atomizing performance. Thus, in the process of thermal atomizing for hot fogging concentrate, atomizer type, the exhaust tube diameter, and the position of the atomizer were the main factors influencing the performance of a thermal atomizer.