Transient Simulation of Speed-No Load Conditions With An Open-Source Based C++ Code

Modern reversible pump-turbines can start in turbine operation very quickly, i.e. within few minutes. Unfortunately no clear design rules for runners with a stable start-up are available, so that certain machines can present unstable characteristics which lead to oscillations in the hydraulic system...

Full description

Saved in:
Bibliographic Details
Published in:IOP conference series. Earth and environmental science 2014, Vol.22 (3), p.32029-32038
Main Authors: Mangani, L, Romanelli, G, Staubli, T, Casartelli, E
Format: Article
Language:English
Subjects:
Casing (process)
Computation
Computer applications
Computer simulation
Draft tubes
Finite element method
Flow distribution
Hydraulic equipment
Local flow
Oscillations
Simulation
Slopes
Source code
Spirals
Synchronism
Synchronization
Turbines
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Modern reversible pump-turbines can start in turbine operation very quickly, i.e. within few minutes. Unfortunately no clear design rules for runners with a stable start-up are available, so that certain machines can present unstable characteristics which lead to oscillations in the hydraulic system during synchronization. The so-called S-shape, i.e. the unstable characteristic in turbine brake operation, is defined by the change of sign of the slope of the head curve. In order to assess and understand this kind of instabilities with CFD, fast and reliable methods are needed. Using a 360 degrees model including the complete machine from spiral casing to draft tube the capabilities of a newly developed in-house tool are presented. An ad-hoc simulation is performed from no-load conditions into the S-shape in transient mode and using moving-mesh capabilities, thus being able to capture the opening process of the wicket gates, for example like during start-up. Beside the presentation of the computational methodology, various phenomena encounterd are analyzed and discussed, comparing them with measured and previously computed data, in order to show the capabilities of the developed procedure. Insight in detected phenomena is also given for global data like frequencies of vortical structures and local flow patterns.
ISSN:1755-1307
1755-1315
DOI:10.1088/1755-1315/22/3/032029