Atomization characteristics of multi-type aerial nozzles in wind tunnel and low airflow velocity condition in manned agricultural helicopter

Abstract

In order to explore the atomization characteristics of the LICHENG series nozzle for manned agricultural helicopter under medium and low airflow velocity conditions, droplet size tests on five sizes of nozzles 11002, 11003, 11004, 11006 and 11010 were carried out by laser diffraction device (LDD), based on the high-low speed composite wind tunnel for agricultural aviation designed by the National Center for International Collaboration Research on Precision Agricultural Aviation Pesticides Spraying Technology (NPAAC) of South China Agricultural University (SCAU). The results showed that under the three spray pressures of 30, 40 and 50 psi, the droplet sizes of the five types of nozzles expressed similar trends with the increase of airflow velocity. Among them, the droplet size variation of nozzles 11006 and 11010 with larger orifice size was the most significant, the largest range of D V0.1 was nozzle 11010, and the largest range of D V0.5 and D V0.9 was nozzle 11006. In addition, the changes of spray pressure would directly affect the quality of spray, especially the nozzles 11002, 11003 and 11004 with small orifice sizes were significantly affected. Under the condition of medium and low airflow velocity of 0-27.8 m/s, 89% of spread value (SV) by the five nozzles were in the range of less than 15%, but there were some test nozzles with poor spray stability during the test, which made the measurements of droplet size value larger, resulting in a maximum test deviation of up to 210.9 I¼m. The result also exposed the limitations exist in wind tunnel droplet size testing by using LDD, and an increase in airflow velocity resulted in a larger measurement droplet size. This phenomenon was particularly significant in the D V0.5 test results of various types of nozzles. This study can provide experimental data guidance for the optimization design and parameter selection of aerial nozzle for manned agricultural helicopter. Keywords: manned helicopter, aerial nozzle, wind tunnel, droplet size, agricultural application, spray classification DOI:  10.33440/j.ijpaa.20190201.0031  Citation: Yao W X, Lan Y B, Hoffmann W C,  Guo S, Chen S D, Wen S, et al.  Atomization characteristics of multi-type aerial nozzles in wind tunnel and low airflow velocity condition in manned agricultural helicopter.  Int J Precis Agric Aviat, 2019; 2(1): 9–17.