Abstract
A circular orifice is a hydraulic device used to measure and control the outflow from tanks, reservoirs and channels. The main purpose of this paper is to study the behaviour of flow through a circular opening of a certain length L and a diameter d and its subordination to the behaviour a pipe or orifice. The discharge coefficient is the factor that will determine which of the two behaviours to be followed for given L and d. To achieve this purpose, laboratory experiments were carried out to investigate the discharge coefficient C-do and C-dp variations with the circular opening diameter d and length L for each orifice and pipe behaviours respectively and developing equations for estimating C-do and C-dp. Four diameter values of 12.7, 19.05, 25.4, and 38.1 mm and eleven lengths of 2, 4, 7.5, 9.25, 20, 50, 100, 200, 400, 600, 1,000 mm were employed to achieve this purpose. The results show that C-do decreases but Cdp increases as L increases. Further, the discharge coefficient for each orifice and pipe behaviour C-do and C-dp are proportional to its diameter d and inversely proportional to the water head h. By using Buckingham Pi theory general chart and equations were developed to estimate the discharge coefficient for each orifice and pipe behaviour C-do and C-dp.