Abstract

Hydroelectric power plants’ open-type surge tanks may be built in mountains subject to the provision of atmospheric air. Hence, a ventilation tunnel is indispensable. The air flow in the ventilation tunnel is associated with the fluctuation of water-level in the surge tank. There is a great relationship between the wind speed and the safe use and project investment of ventilation tunnels. To obtain the wind speed in a ventilation tunnel for a surge tank during transient processes, this article adopts the one-dimensional numerical simulation method and establishes a mathematical model of a wind speed by assuming the boundary conditions of air discharge for a surge tank. Thereafter, the simulation of wind speed in a ventilation tunnel, for the case of a surge tank during transient processes, is successfully realized. Finally, the effective mechanism of water-level fluctuation in a surge tank and the shape of the ventilation tunnel (including length, sectional area and dip angle) for the wind speed distribution and the change process are discovered. On the basis of comparison between the simulation results of 1D and 3D computational fluid dynamics (CFD), the results indicate that the one-dimensional simulation method as proposed in this article can be used to accurately simulate the wind speed in the ventilation tunnel of a surge tank during transient processes. The wind speed fluctuations can be superimposed by using the low frequency mass wave (i.e., fundamental wave) and the high frequency elastic wave (i.e., harmonic wave). The water-level fluctuation in a surge tank and the sectional area of the ventilation tunnel mainly affect the amplitude of fundamental and harmonic waves. The period of a fundamental wave can be determined from the water-level fluctuations. The length of the ventilation tunnel has an effect on the period and amplitude of harmonic waves, whereas the dip angle influences the amplitude of harmonic waves.

Highlights

  • It is necessary to carry out a simulation of the wind speed the wind speed during transient processes to provide a basis for the application and design of during transient processes to provide a basis for the application and design of ventilation tunnels in ventilation tunnels in the case of surge tanks

  • The one‐dimensional numerical simulation of wind discussed the transient flow in a natural gasofpipeline and established basic equations. In this speed in a ventilation tunnel, for the case a surge tank during its transient processes, hasregard, not been they proposed to use the one-dimensional method of characteristics (MOC)

  • Effective mechanism of water‐level fluctuation in a surge tank and the shape of the ventilation tunnel for onward distribution and the wind speed change process have been explored from the perspective of wave superposition

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Summary

Introduction

The one‐dimensional numerical simulation of wind discussed the transient flow in a natural gasofpipeline and established basic equations In this speed in a ventilation tunnel, for the case a surge tank during its transient processes, hasregard, not been they proposed to use the one-dimensional method of characteristics (MOC). By comparing the results of one‐dimensional simulation effective mechanism of water-level fluctuation in a surge tank and the shape of the ventilation tunnel that of three‐dimensional CFD simulation through a project case, the applicability and the rationality of (including length, sectional area and dip angle) for onward distribution and the wind speed change one‐dimensional numerical simulation as proposed in this article have been verified. Effective mechanism of water‐level fluctuation in a surge tank and the shape of the ventilation tunnel (including length, sectional area and dip angle) for onward distribution and the wind speed change process have been explored from the perspective of wave superposition

Mathematical Model
Basic Equations and Solution of MOC
A B x BM t B p “ 0
Boundary Conditions
A J vJ pJ
CP1 p P “ C CM2
B MJ obtained as follows
Model Verification
Simulation Method
Analysis
Effect
Length of Ventilation Tunnel
Sectional Area of Ventilation Tunnel
Dip of Ventilation
Summary forof thewater‐level
Conclusions
Full Text
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