The current study carried out in the Federal Biological Research Centre for Agriculture and Forestry (JKI) Braunschweig, Germany. The goals of this research were to measure the droplet size for the developing external mixing twin fluid nozzles (EMTF) that will target and spray the pesticide, especially biological and herbicides pesticides. As well as investigating to find the optimum combinations of the EMTF nozzles from the available nozzles that applied in the field of agriculture. Also the reduction of the water volume rate is an important aspect in the current research to reduce application costs. The tongue nozzle (Lechler FT5-608) for the air and the eight different nozzles from Lechler and Tee Jet for the liquid nozzle were selected to obtain the combinations of EMTF nozzles. Oxford lasers “VisiSizer" system PDIA was used to test and measured the droplets size from different EMTF nozzles.
The two levels of air pressures 150 (1.5 bar) and 200 kPa (2 bar) at liquid pressures 30 (0.3 bar) and 60 kPa (0.6 bar) and two co/angling (injection angles) 60° and 45° were tried to study their effect on droplets size, as well as to find the optimum EMTF nozzle configuration. It was found that the external mixing twin fluid could be producing the different droplet spectrum from medium to very fine droplet at low liquid pressure. The external mixing twin fluid nozzle combination N1 (TT11003+ Lechler FT 5 - 608) produce the medium spectrum compared to the N2, N2, N3, N4, N5, N6, N7 and N8 EMTF nozzles combinations. The spray characteristics droplets size Dv0.1, Dv0.5 and Dv0.9 for N1 EMTF nozzle are 95.2 µm, 226.6 µm, and 486.3 µm at 150 kPa (1.5 bar) air pressures; and 77.2 µm, 171.2 µm, and 450 µm at 200 kPa (2 bar) air pressures respectively.
On the other hand, the N5 (Lechler LU 120-015 POM +Lechler FT 5 – 608) nozzle produce the fine spectrum at the above air and liquid pressure conditions. As well as the result indicated that the external mixing twin fluid could be reducing the water volume rate. The increase of liquid pressure tends to decrease of the droplet size spectra. By changing the injection angle may able to produce the finest droplet without any increasing of the applied costs. Also it is able to use the widely available agricultural nozzles to make the external mixing twin fluid which are working at low spray pressure.