Leakage Measurement for Hydro Turbine Guide Vane

Abstract

The objective of this thesis was to develop a calculation tool for the commissioner to estimate guide vane leakages of vertical axis Kaplan and Francis hydro turbines. The calculation was intended to be based on guide vane clearance measurements. The background of the work was challenges related to the determination of guide vane leakages, as the current method does not always guarantee reliable results. The work was commissioned by Fortum Power and Heat Oy and it was carried out as a Fortum Research & Development project. There was utilized articles and expert discussions at the work to gain insight into the function of the guide vanes and their inspections. In addition, other methods by which guide vane leakages could be determined were investigated. The calculation of guide vane leakage was viewed from the perspective of Bernoulli equation. The basics of the calculation were simplified, and certain deviations were made. The obtained calculation method was considered to be sufficiently accurate and reliable to use. The result of the work was a workable Excel-based calculation tool, which the client intends to use in its inspections. The tool was used to calculate guide vane leakages from turbines for which measurement data were available. The results were compared with another method in use and compared to this, the leakages obtained were slightly higher with the calculation tool. The results obtained by the calculation tool were evaluated on the basis of the economic losses caused by them, the results of which can be used for possible improvement purposes.