Project Number: 3607-21620-008-19
Project Type: Specific Cooperative Agreement

Start Date: Feb 01, 2010
End Date: Jan 31, 2013

Objective:
Determine the effect of wind speeds on the evaporation rates of pheromone from standard releasers. Develop a computer simulation program, based on two-phase flow dynamic models, to determine spray off-target losses from air-assisted sprayers used in crop productions from trees.

Approach:
Evaporation rates of pheromone droplets will be tested in a wind tunnel specifically designed for this investigation. Wind speed is the main variable. Fifteen load cell units installed in the wind tunnel will be used to measure evaporation rates of pheromone droplets. The study of pheromone evaporation rates, totaling 165 treatments, will include 11 constant air speeds ranging from 0 to 10 m/s, five pheromone releaser surface areas, and pheromones of three molecular weights. Ambient air temperature will be maintained at 25°C for all tests. Computer simulation programs will be developed for the prediction of spray droplet deposition discharged from air-assisted sprayers under different microclimatic conditions. The programs will use the mathematical models and algorithms based on simulation results from a computational fluid dynamics program (FLUENT). Two-phase flow models with stochastic process under turbulent conditions will be developed and used in the computer simulation. Evaporation of droplet dispersal will be included in the models. A CAD program (Pro/ENGINEER) will be used to establish geometries of nozzles, sprayers and trees. The join-mapping technique will be used to incorporate the geometrics of sprayers and field targets into FLUENT for simulation. Variables in the models include wind velocity, turbulence intensity, canopy structure, ambient temperature, relative humidity, spray droplet size distribution, space ratios between droplets and air, sprayer structure and travel speed. The accuracy of the computer simulation models for air-assisted sprayers will be verified under controlled conditions in a wind tunnel and in orchard and nursery fields.