Calculation Method of Cavitation Coefficient of Vertical Shaft Francis Turbine Power Plant

Abstract

The invention relates to hydropower station water turbines and discloses a vertical shaft mixed-flow water turbine power station cavitation coefficient calculation method for calculating vertical shaft, mixed-flow water turbine power station cavitation coefficient. The method includes: determining specific rotating speed ns of a mixed-flow water turbine; determining maximum application water head Hmax of the mixed-flow water turbine, and judging a range of the Hmax; calculating power station cavitation coefficient sigma p according to a power station cavitation coefficient calculation formula of the range corresponding to the Hmax, wherein the power station cavitation coefficient calculation formula of the range includes when Hmax is smaller than or equal to 100m, sigma p=2x10<-5>ns<1.6662>, when Hmax is greater than 100m and smaller than or equal to 200m, sigma p=2x10<-5>ns<1.6816>, when Hmax is greater than 200m and smaller than or equal to 300m, sigma p=5x10<-6>ns<1.9665> and when Hmax is greater than 300m, sigma p=7x10<-5>ns<1.4383>. The method is suitable for calculating the vertical shaft mixed-flow water turbine power station cavitation coefficient and can better meet new hydropower engineering requirements.

Description

technical field [0001] The invention relates to a water turbine in a hydropower station, in particular to a calculation method for the cavitation coefficient of a vertical shaft mixed-flow turbine power station. Background technique [0002] In hydropower stations with vertical-shaft Francis turbines, the turbine suction height H s It is the elevation difference from the center line of the guide vane (that is, the installation elevation of the turbine) to the tail water level of the power station. Raising the suction height and installation elevation of the turbine can reduce the underwater engineering volume and investment of the main powerhouse; while reducing the suction height and installation elevation of the turbine can improve the cavitation performance of the turbine, which is conducive to the stable operation of the unit and prolongs the service life of the unit. Therefore, how to reasonably determine the suction height of the turbine is an important content of hyd...

AI Technical Summary

Problems solved by technology

Since this method estimates the cavitation coefficient σ of the power station according to the statistical formula p , there are many statistical formulas of this kind at present, because the water turbine parameter sample data on which each statistical formula is based is before the 1970s and 1980s or a certain water head section or a certain specific speed n s range, there are certain limitations, the results estimated by different statistical formulas for the same hydropower project are different, and some even have large differences, so it is impossible to correctly select

Therefore, both methods 1 and 2 cannot meet the requirements of hydropower engineering for the continuous development of new technologies, new materials, new processes, and new structures. The estimated cavitation coefficient σ p Generally, it is also difficult to meet the new hydropower engineering requirements

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