Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
AN EXTENDED AXIAL MOMENTUM ANALYSIS FOR STEAM TURBINES
Submission Author:
Davi Oliveira , PA , Brazil
Co-Authors:
Davi Oliveira, Jerson Vaz, Mauro Veloso
Presenter: Davi Oliveira
doi://10.26678/ABCM.COBEM2021.COB2021-0605
Abstract
Classically steam turbines are analyzed using cascade methods, which can be applied to impulse or reaction rotors. On both kind of turbines, the stator is indeed necessary as it may change pressure and velocity on the rotor blades, making the turbine efficiency about 70%. However, the stator turns the steam turbine more complex to design, even for one stage. In this work, an extended axial momentum analysis applied to steam turbine is developed. The approach takes into account a combination of the kinect energy transported by the steam flow and the effect of enthalpy drop throughout the rotor, affecting the turbine efficiency. Methods based on axial momentum theory are important because they open the possibility of designing steam turbine blades without the need of stator. As a result, the proposed approach can exceed the turbine efficiency beyond Betz limit (59.3%), reaching about 90% or more depending on the impact of the enthalpy variation through the steam rotor. Also, the coupling of the extended axial momentum analysis with the blade element theory can result in a new expression to optimize steam turbine blades.
Keywords
Steam turbines, Axial momentum theory, Turbine efficiency
