The study of the influence of stabilizing devices on the pressure pulsations at the free discharge of water through the turbine

Dmitry Platonov,Dmitry Dekterev,Andrey Minakov,S.V Alekseenko

doi:10.1051/matecconf/201711506002

Dmitry Platonov, Dmitry Dekterev + Show 2 more

Open Access

https://doi.org/10.1051/matecconf/201711506002

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Abstract

The free discharge through the turbine is applied in the course of construction of hydro power plant or in case of excessive water inflow during floods or emergency situations. The experimental and numerical investigation of flow-induced pressure pulsations in hydraulic turbine draft tube at free discharge was performed using a special setup for suppression of draft tube surge. Such special equipment in draft tube cone as fins and “spider”-like units was considered for reducing these pressure pulsations. The paper considers influence of these units on vortex structures and pressure pulsations in the draft tube in several regimes.

Highlights

Low-frequency flow-induced pulsation occurs in Francis and Kaplan hydraulic turbines at off-design operation
Air supply in the draft tube model was carried out using a high performance air blower with the maximum flow rate Qmax =170 m3/h and the excess pressure of Δp=0.4 bar
It was possible to maintain the flow regime with an accuracy of 1.5% and 0.5% of the flow rate and the runner rotation frequency, respectively

Summary

Introduction

Low-frequency flow-induced pulsation occurs in Francis and Kaplan hydraulic turbines at off-design operation. The pulsation is associated with the unsteady swirling flow in the draft tube of the hydraulic turbine. Air admission is the most widely used method [3] This method is too expensive in case of static pressure at the aeration point exceeding atmospheric pressure. Another way is special equipment for stable operation. The special equipment influences the flow to reduce or destroy the vortex rope. There is such equipment as fins on the draft tube walls, a spider-like unit under the runner, a hollow cylinder under the runner hub, etc. Disadvantages of the fins are loss in the efficiency of the turbine and necessity to guard the fins from cavitation erosion and structural damage [5]

Experimental and numerical techniques

The results

Findings

Conclusions