The Transient Characteristics of Fluid Pipes including Mechanical Load : 3rd Report, Experimental Analysis on Effects of Valve Closure

Abstract

This paper deals with transient characteristics of a valve-controled hydraulic driving system consisting of actuator, fluid pipe and operation valve, especially with pressure surge generation in a pipe due to sudden valve closure. Pressure variation was measured under various system and operating parameters, such as valve closure time, valve closure process, valve orifice shape, etc., and compared with theoretical results of the preceding paper. Consequently, the following matters became evident. (1) The theoretical results which were obtained by employing a wave equation of two-dimensional viscous flow for an unsteady pipe flow agree well with experimental results in any system parameters and valve closure process. (2) An approximate solution which was obtained by considering only the compressibility of fluid in pipe is accurate enough for practical usage in case of very slow valve closure. (3) Variation of discharge coefficient of valve depending on Reynolds number, saturation of valve flow at large opening and leakage flow through valve orifice after closure can not be disregarded in case of gradual valve closure.