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A gate valve is used to regulate discharge in pipelines. It is rotated by a wheel that is attached to a circular disc (i.e. gate) at the top of a stem. Each revolution of the wheel creates a particular linear disc movement that changes the flow zone. The paper describes the journey of gate valve from flow control device to flow measuring device and presents an experimentation on conventional gate valve and gate valve with flexible membrane pipe. The findings of experimental study are described and validated with CFD analysis of conventional and modified gate valve. The experimental study has shown that the modified gate valve can be used as flow measuring device. The results obtained represent the excellent improvement in the relationship between disc position (i.e., angle) and discharge. The results of CFD analysis for flow through gate valve with and without flexible membrane are compared. After carrying out the CFD studies without flexible membrane, it is found that, fluctuating separation zones formed on either side of gate are responsible to a great extent to the flow rate descripancies. This paper compares the experimental and CFD results and also suggests the remedy to address the problem. Article highlights Introduced simply a flexible membrane pipe inside PVC to convert gate valve into flow measuring device. Reduction in flow separation and fluctuation in flow rate. Smooth flow rate even though gate valve opening is small.

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Present study highlights the behavior of weir crest head and width parameter on the discharge coefficient of compound broad crested (CBC) weir. Computational fluid dynamics model (CFD) is validated with laboratory experimental investigations. In the discharge analysis through broad crested weirs, the upstream head over the weir crest (h) is crucial, where the result is mainly dependent upon the weir crest length (L) in transverse direction to flow, water depth from channel bed. Currently, minimal investigations are known for CFD validations on compound broad crested weirs. The hydraulic research for measuring discharge numerically is carried out using FLOW 3D software. The model applies renormalized group (RNG) using volume of fluid (VOF) method for improved accuracy in free surface simulations. Structured hexagonal meshes of cubic elements define discretized meshing. The comparative analysis of the numerical simulations and experimental observations confirm the performance of CBC weir for precise measurement of a wide range of discharges. Series of CFD model studies and experimental validation have led to constant range of discharge coefficients for various head over weir crest. The correlation coefficient of discharge predictions is 0.999 with mean error of 0.28%.