Abstract
The T-shaped branch pipe is one of the most basic elements in pipe line systems. Because the evaluations on the energy losses in this pipe are very important for practical use, many investigations have been made. In this branch pipe, when the pressure becomes lower and/or the velocity in main pipe increases, the cavitation is induced in the neighborhood of the junction of main and lateral pipes. In the past, as far as the authors know, these cavitation characteristics have not been published except in that of the T-shaped branch pipe with a single lateral pipe. In this paper, therefore, the cavitation characteristics of the T-shaped branch pipe consisting of main pipe and two symmetrical lateral pipes were experimentally investigated. First, for the T-shaped branch pipe with equal square cross sections of main and lateral pipes, called the fundamental type branch pipe, the aspects of cavitation occurrence were observed in detail and its critical condition was pursued experimentally. Then, for the T-shaped branch pipe with different cross sections of main and lateral pipes and the one with different shapes of branch part from the fundamental type, the experiments were made in the same manner as above described. The shapes of branch part used in this experiment were: one having the radius of curvature in branch corners, one having the extension which represents the continuation of main pipe, and one placing the dividing plate at the front wall of lateral pipe. Also, under the different conditions of flowing-in into the junction the cavitation characteristics of this branch pipe were investigated. It was recognized that the cavitation appeared in separated flow from branch corners and in a pair of vortices formed by secondary flow at branch part, the critical condition of cavitation occurrence depended on shape of the neighborhood of junction and ratio of flow rate, and the cavitation characteristics were best in branch pipe with rounded corner at the junction of main and lateral pipes.
