Mechanical & Materials Engineering, Department of


Date of this Version



A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Mechanical Engineering, Under the Supervision of Professor George Gogos. Lincoln, Nebraska: May, 2012

Copyright 2012 Brian D. Neilson


Flaming is a thermal weed control method that can kill weeds within or between crop rows using heat. Mechanical cultivation is another weed control method which undercuts weeds between crop rows to kill them. A combination flamer/cultivator implement was designed to take advantage of the good qualities of both flaming and cultivation to provide excellent organic weed control.

Flaming hoods were designed in the spring of 2010 and retrofitted on an existing row crop cultivator. The hoods were tested in corn and soybean field studies in the summer of 2010. Of the seven treatments tested, a treatment of flaming combined with cultivation applied twice during a season produced the highest weed control and crop yield, while maintaining low crop injury and weed dry matter.

The flaming hoods were redesigned in the spring of 2011 to be easier to manufacture. New torches were developed to replace the commercial torches previously used. A flow mixer enhanced heat transfer by reducing or eliminating film evaporation. Reducing the primary air intake decreased flame liftoff length and improved stability.

The new hoods and torches were tested in the same seven field treatments during the summer of 2011. Flaming combined with cultivation twice performed best overall again, although the actual values of the performance parameters were lower than in 2010. There are several factors which may have caused worse results in 2011 than in 2010. These include changes in weed composition and density, equipment, climate, and planting date.

Gas temperature measurements were conducted on three of the hood/torch configurations used in the field studies, as well as on open, unhooded torches. Thermocouple heat losses due to radiation were accounted for, and ranged from 0.9 percent to 29.4 percent. The hooded torches were far superior to the open torches, increasing the high-temperature region length by approximately 200 mm. The 2010 hood provided temperatures that were 36 percent higher at the hottest cross-section than the 2011 hood, but the latter performed better overall.

Adviser: George Gogos