Accurate stage-by-stage modelling of axial turbines using an appropriate nozzle analogy with minimal geometric data

作者：Fuls W F^*

来源：Applied Thermal Engineering, 2017, 116: 134-146.

DOI：10.1016/j.applthermaleng.2017.01.048

• Steam turbine modelling
• Nozzle flow
• Flownex
• Impulse
• Reaction
• Governing stage

This paper presents a methodology to model a turbine on a stage-by-stage basis using nozzle flow analogy, requiring minimal detail information of the geometry of the individual blade passages. The classical nozzle theory is slightly expanded such that a turbine stage can be represented as a series of two nozzles with appropriate inlet conditions and loss factors. Conservation equations and component characteristics are presented which can be programtned into a simultaneous solver.
The thermo-hydraulic network solver Flownex was used to model the nozzles in such a manner. This enabled the definition of a custom turbine stage component, which was then used to model a 4-stage air turbine, as well as two steam turbines of an arbitrary power plant. The model predicted the turbines' off design (low load) conditions very well, considering the limited information used to set up the models.
The approach can be used for accurate prediction of a turbine's off-design and abnormal operation, provided the physical geometry of the turbine remains unchanged. Plant operators can use this method to obtain better information regarding the inter -stage process conditions of a turbine, without requiring detail design information or complex CFD software.

• 出版日期2017-4