Multiple analysis approach for the design of the labyrinth spillway on the Nam Teng river, Myanmar: Concept design - CFD - physical model

Abstract

This paper presents the results of a combined approach - concept design, Computational Fluid Dynamics (CFD) simulations and physical model test - to design a spillway on the Nam Teng River in Myanmar. The spillway includes a 140 m wide labyrinth weir which ensures that the PMF flow QPMF=6800 m3/s passes with a maximum head of 5.5 m. The width required to pass PMF flow for a conventional ogee shaped weir is ca. 200m. The design of the spillway is based on design recommendations for labyrinth weirs from Tullis [1] and USBR guidelines to design the chute, stilling basin and outfall channel that leads the flood flow back to the river. The CFD simulations helped to improve the flow condition at the entrance and towards the labyrinth weir by altering the approach channel. The physical model tests confirmed the capacity of the labyrinth weir, investigated blockage risk due to floating debris. The design modifications made based on the physical model tests have increased the hydraulic performance and safety of the spillway and made the construction cheaper and simpler (less excavation and civil work).