Turbine Nozzle Blade and Steam Turbine Equipment Using Same

Abstract

Disclosed is a highly efficient turbine nozzle blade that reduces the number of blades in an axial-flow turbine while reducing secondary-flow loss. In the nozzle blade, when a differential pressure between a pressure side and a suction side of each blade, at the same axial chord position of the blade, is defined as a load of the blade, and a ratio between axial chord length “Cx” of the blade and an axial distance “xp” from a leading edge of the blade at a maximum load position that maximizes the blade load is defined as a maximum load relative position, Cx is greater at a hub and tip than at an intermediate vertical portion, and simultaneously a maximum load relative position at the hub and tip is set to be nearer to a trailing edge thereof than a maximum load relative position of the intermediate vertical portion of the blade.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a turbine nozzle blade used for axial-flow turbines, especially gas turbines, steam turbines, and the like, at electric power plants.[0003]2. Description of the Related Art[0004]In recent years, it is strongly requested to further enhance turbine performance for the purpose of an improvement in electric-power generating efficiency at power plants. Turbine performance is involved in the stage loss, exhaust loss, and mechanical loss of the turbine, and it is considered to be most effective to reduce the stage loss, in particular, for turbine performance improvement. There are various types of stage loss. Such stage loss can be roughly categorized, namely, (a) profile loss due to the blade shape itself, (b) secondary-flow loss due to a working fluid flow not along a main flow of the working fluid, and (c) leakage loss caused by leakage of the working fluid from the main flow. The secondary-...

AI Technical Summary

Benefits of technology

[0007]The present invention is intended to provide a turbine nozzle blade minimized in contact area between a blade and a flow of fluid by reducing the number of blades to a minimum requirement for a desired direction change of a fluid flow in order to reduce blade profile loss. And at the same time, the turbine nozzle blade is further improved in stage efficiency of the turbine by optimizing a load distribution and axial chord length near an endwall in order to reduce secondary-flow loss due to interference between the blade and a boundary layer on the endwall. The reduction in the number of blades also contributes to reduction in manufacturing costs of the turbine and to supply of a turbine high in efficiency and low in manufacturing costs.

[0009]The above configuration enables supply of a turbine nozzle blade in which reducing the number of blades is effective for reducing secondary-flow loss in addition to profile loss, and hence for improving turbine stage efficiency.

[0010]The reduction in the number of blades further contributes to reduction in manufacturing costs of the turbine and to supply of a turbine high in efficiency and low in manufacturing costs.

Problems solved by technology

JP-2008-202420-A, however, does not describe on a stagger angle of the blades and on a load distribution in an axial chord direction, and a reduction effect against secondary-flow loss has been unlikely to be fully brought about with the conventional technique involved.

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