A piezoelectric film sensor improvement and evaluation for measuring water droplet impact energy and determining droplet impact effects on soil surfaces

The overall objectives of this research were to test the response linearity of a large piezoelectric film to water droplet impact and to evaluate the sensor in a real application of measuring water droplet impact. A piezoelectric film with a large sensing area (203 mm long x 140 mm wide) was used in this research. The sensing area was divided into five sections to test the sensor similarity. Water drops of the same kinetic energy were allowed to hit each section several times. The output of each section was averaged and compared with the output of the other sections to test the sensor similarity. The results of the similarity test show that the sensor responded similarly to the same water droplet impact at different locations on the sensing area.;Then, the piezoelectric film was calibrated using water drops of different sizes released from specific heights. The calibration data was used to develop a calibration curve for this particular type of piezoelectric film. The result showed that piezoelectric film responded linearly to varying water droplet impact forces.;Sprinkler droplet kinetic energy generated by a 6.35 mm nozzle at three operating pressures was measured using the piezoelectric film. The result showed that kinetic energy produced by the sprinkler decreased as operating pressure increased. The output data was analyzed and used to develop a simulation model for predicting kinetic energy under sprinkler irrigation.;Finally, the effect of droplet impact produced by irrigation sprinklers on erosion was investigated using a simulated section of a center pivot irrigation system. The system was assembled in the laboratory and consisted of 4 nozzles spaced 2.44 m (8 ft) apart. Runoff samples were collected every 5 min for about 210 min at three operating pressures. After measuring the runoff volume of each sample, the sample was oven dried to determine the eroded soil mass. The erosion results, in conjunction with the kinetic energy measurement results, were used to develop a mathematical model to predict soil erosion under the sprinkler.