Start Date

2018 4:20 PM

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Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Abstract

The increasing magnitude of design floods has prompted re-evaluations of spillway capacity for large dams throughout the world. Current capacity of many spillways is inadequate. The overtopping creates new loading scenarios for the dam and raises questions about erosion and scour downstream from the dam. Detailed studies of overflow nappe impinging jets in plunge pools are scarce. This work addresses such situation, and compares numerical results against our own experiments. The hydraulics laboratory at the Universidad Politécnica de Cartagena has a turbulent jet experimental facility in which the energy dissipation of turbulent rectangular jets is being studied. The mobile mechanism allows researchers to vary the discharge heights between 2.20 and 3.50 m and flows from 10 to 200 l/s. To advance the understanding of the phenomenon, the kinetic energy was registered at the inlet channel and instantaneous velocity measurements in the plunge pool with Acoustic Doppler Velocimeter (ADV) equipment, mean velocities and air entrainment rate in different sections of the falling jet and in the plunge pool with optical fiber instrumentation, and the LS-PIV (Large Scale – Particle Image Velocimetry) procedure was applied. At the same time, transient numerical simulations were carried out with computational fluid dynamics (CFD) programs. Two-equation turbulence models were selected to solve the closure problem of the Reynolds-Averaged Navier-Stokes equations. This work analyses and compares the laboratory data in the plunge pool with the numerical simulations carried out with ANSYS CFX.

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May 16th, 4:20 PM

Characterization of Two-Phase Flows in Plunge Pools

The increasing magnitude of design floods has prompted re-evaluations of spillway capacity for large dams throughout the world. Current capacity of many spillways is inadequate. The overtopping creates new loading scenarios for the dam and raises questions about erosion and scour downstream from the dam. Detailed studies of overflow nappe impinging jets in plunge pools are scarce. This work addresses such situation, and compares numerical results against our own experiments. The hydraulics laboratory at the Universidad Politécnica de Cartagena has a turbulent jet experimental facility in which the energy dissipation of turbulent rectangular jets is being studied. The mobile mechanism allows researchers to vary the discharge heights between 2.20 and 3.50 m and flows from 10 to 200 l/s. To advance the understanding of the phenomenon, the kinetic energy was registered at the inlet channel and instantaneous velocity measurements in the plunge pool with Acoustic Doppler Velocimeter (ADV) equipment, mean velocities and air entrainment rate in different sections of the falling jet and in the plunge pool with optical fiber instrumentation, and the LS-PIV (Large Scale – Particle Image Velocimetry) procedure was applied. At the same time, transient numerical simulations were carried out with computational fluid dynamics (CFD) programs. Two-equation turbulence models were selected to solve the closure problem of the Reynolds-Averaged Navier-Stokes equations. This work analyses and compares the laboratory data in the plunge pool with the numerical simulations carried out with ANSYS CFX.