Liquid Jet Flow into Still Gas : The Effect of Nozzle Loss Coefficient and Area Coefficient on the Core-Length of Water Jet

Abstract

Concerning the research on the optimum nozzle dimension for hydraulic coal mining and other hydraulic processes, an experiment on the core-length L of turbulent water jet has been caried out on 45 nozzles of various configurations. Increasing the jet velocity, L passes certainly three stages : increasing, decreasing, at last saturating. From the consideration of dimensional relation, an empirical formula for the saturated value of L is given by [numerical formula] where ζ_s is the hydraulic loss coefficient of nozzle at very high Reynolds number, while f_Ls is the function of m the area coefficient of nozzle. For ζ_s<0.26, L_s/d does not depend on ζ_s. The optimum value of m is nearly 0.2, which gives the maximum value of L_s.