The effects of oscillating nozzle on Christiansen's uniformity coefficient

Abstract

Rainfall simulators have been used in research for more than 40 years. Unfortunately, there is not much literature on their construction and calibration. This paper presents a rainfall simulator experimental rig, developed at the Faculty of Civil Engineering in Subotica, and its calibration, i.e. determination of rainfall distribution over the surface. The simulator uses six VeeJet 80100 oscillating nozzles equally spaced with 100 cm distance along a horizontal pipe. A box for rainfall intensity reduction is placed under each nozzle. The maximum rainfall intensity that can be achieved is 3,1 mm/min and maximum surface covered by the simulator is 1x6 m(2). As a measure of uniformity of rainfall distribution over the surface, the Christiansen's uniformity coefficient was used. For surface widths ranging from 0,1 to 1 m, the Christiansen's coefficient varies from 0,8 to 0,9 for the oscillating nozzles, while for the non-oscillating nozzle it has a value of 0,46.