Investigation on Surface Wave Characteristic of Water Jet

Abstract

Water jet surface stability is important to enhance fighting efficiency of fire water monitor. In this paper, a visualization experimental method is designed to capture the surface waves of water jet out from fire water monitor, and the wavelength and the amplitudes are captured and measured from the obtained water jet images. The Sobel horizontal gradient direction template and Burg method are selected to obtain wavelength characteristic of water jet. Based on surface morphology, the relationship between wave characteristic of water jet and Weber number is also discussed. The structure of the surface wave changes from cosmic turbulence to stochastic small-scale waves with increasing Weber number and becomes fully chaotic finally. The average wavelength of water jet out from fire water monitor decreases with increasing Weber number. The growth rate in the presence of wavelength with the lower Weg is less than that of the higher Weg. Furthermore, the amplitudes of the water jet increase continuously with increasing flow distance and Weg. In other words, the larger the Weber number is, the faster the velocity of surface waves on water jet is. The main objective of the present work is to give the basis for better understanding the microstructure of water jet, which in turn improves the performance of fire water monitor.