Effect of Downstream Expansion of a Long-Throated Flume on Flow Properties

Long throated flumes are widely used flow measurement devices that not requiring site-specific level to flow curves and therefore laboratory experiments. In this study, downstream expansion effect of the long throated flumes with rectangular cross section were analysed for the dimensionless parameters derived from Buckingham’s pi theorem and some other known hydraulic quantities such as discharge coefficient, approach velocity coefficient, submergence ratio of the flow etc. Therefore, five downstream transitions with different expansion angles were tested. In each test, the critical depth yc, the flow head at the depth measurement section h1, minimum required energy dissipater length Lt and the head after hydraulic jump y2 were measured for both modular and free flow conditions. The relation of hydraulic quantities of calculated dimensionless parameters with relevant parameters; modular limits, approach velocity coefficients and discharge coefficients etc. were graphed to represent the design relationships for long throated flumes. Long throated flumes are widely used flow measurement devices that not requiring site-specific   level to flow curves and therefore laboratory experiments. In this study, downstream expansion  effect of the long throated flumes with rectangular cross section were analysed for the   dimensionless parameters derived from Buckingham’s pi theorem and some other known   hydraulic quantities such as discharge coefficient, approach velocity coefficient, submergence ratio of the flow etc. Therefore, five downstream transitions with different expansion angles were  tested. In each test, the critical depth yc, the flow head at the depth measurement section h1,   minimum required energy dissipater length Lt and the head after hydraulic jump y2 were measured   for both modular and free flow conditions. The relation of hydraulic quantities of calculated   dimensionless parameters with relevant parameters; modular limits, approach velocity  coefficients and discharge coefficients etc. were graphed to represent the design relationships for   long throated flumes.