Research on the Turbine Blade Vibration Base on the Immersed Boundary Method

Abstract

This paper is concerned with the study of a kind of discrete forcing immersed boundary method (IBM) by which the loosely aero-elasticity coupled method is developed to analyze turbine blade vibration. In order to reduce the spurious oscillations at steep gradients in the compressible viscous flowing field, a five orders weighted essentially nonoscillatory scheme (WENO) is introduced into the flow solver based on large eddy simulation (LES). The three-dimensional (3D) full-annulus domain of the last two stages of an industrial steam axial turbine is adopted to validate the developed method. By the method, the process of grid generation becomes very simple and the unsteady data transferring between stator and rotor is realized without the process of being averaged or weighted. Based on the analysis of some important aerodynamic parameters, it is believed that hypothesis of azimuthal periodicity is not reasonable in this case and full-annulus passages model is more feasible and suitable to the research of turbine blade vibration. Meanwhile, the blade vibration data are also discussed. It is at about 65% of rotor blade height of the last stage that an inflection point is observed and the midspan region of the blade is the vulnerable part damaged potentially by the blade vibration.

Numerical investigation on flow instabilities in low-pressure steam turbine last stage under different low-load conditions

“…In the worst case, it may coincide the natural frequency of the blade, thus intensifying the forced vibration. 7 Therefore, it is equally important to predict the intensity and propagation characteristics of perturbations and to explore their mechanisms. Traditional tests can give accurate feedback but are too costly and rigid to integrate into an early design.…”

Research on the Ghost Cell Immersed Boundary Method for Compressible Flow

“…Zhang [17] adopted an improved ghost cell scheme to simulate the interaction between the reflected shock and the boundary layer and then study the shock propagation in a wavy-walled tube. Liu [18] introduced a discrete cell method into the in-house flow solver to develop a loosely coupled aero-elasticity scheme, through which turbine blade vibration induced by the unsteady flowing was researched with the full-annulus passages model. However, many researchers have found that an unphysical velocity field near the immersed boundary could be unwillingly introduced sometimes.…”

The study of vertical-axis wind turbine based on immersed boundary method

“…Barba and Stoesser (2017) applied the IBM to 3D incompressible flowing simulation to study a real hydrokinetic turbine. Liu et al (2018) adopted a kind of ghost-cell IBM to develop a coupled aero-elasticity scheme, by which the blade vibration of a stream turbine triggered by the unsteady aerodynamic force was analyzed based on a full-annulus passages model. Gaikwad et al (2021) described on how to adopt a ghost-point IBM in a finite-difference large-eddy code to simulate flow in atmospheric boundary layer over hills or cliffs.…”