Research on Mixing Law of Liquid Fertilizer Injected into Irrigation Pipe

Abstract

The time and position that fertilizer takes to uniformly mix with water in an irrigation system significantly affects the development of a fertilization strategy. A pipe irrigation system was used to study the fertilizer–water mixing law in irrigation pipes using numerical simulation and experiments. The effect of the diameter of the water pipe and fertilizer pipe, water and fertilizer flow rates, concentration and viscosity of fertilizer, frequency of fertilizer injection on the mixing speed, and uniform mixing length indicated that the frequency of fertilizer injection did not affect the mixing process. The increase in the water pipe diameter and fertilizer flow rate or the decrease in fertilizer pipe and water flow rate diameter result in the increase of the speed of fertilizer solution mixing with water along the radial direction of the mixing pipe. The uniform mixing length was directly proportional to the fertilizer pipe diameter, water pipe diameter, water flow rate, and fertilizer viscosity, while it was inversely proportional to the flow rate and concentration of fertilizer. The relationship between the uniform mixing length and six influencing factors was fitted, the fitting was highly accurate, and the fitting equation can be used to predict the uniform mixing length under other conditions.