Experimental Validation of Empirical Methods for Dynamic Stress Prediction in Turbomachinery Blades

Abstract

Turbomachinery blade fatigue life estimation requires reliable knowledge of actual static and dynamic stresses occurring within the blades. A common method for predicting dynamic stresses is to construct a finite element model of the blade and simulate the dynamic response to aerodynamic loads. Although this method is powerful and very useful, modeling errors (geometry, boundary conditions, stress concentrations, damping, etc.) may result in inaccurate stress predictions. Furthermore, unavoidable variability in manufacturing results in blade mistuning, which significantly affects stress amplification at resonance. This paper presents two empirical methods for predicting dynamic stresses in turbomachinery blades that include the actual effects of structural damping and mistuning. Both methods use strain gauge measurements from a blade modal test to obtain load to strain transfer functions, which are applied to predict the blade strain or stress response to a simulated load. The advantages and disadvantages of each method are discussed. The predictions of each method are compared with dynamic blade strain data acquired during a rotating test of a centrifugal compressor impeller.

Dynamic stress of impeller blade of shaft extension tubular pump device based on bidirectional fluid-structure interaction

“…In view of fluid-structure interaction effect, Langthjem et al [4] studied the flow-induced noise of a centrifugal pump. Nevertheless, few researches have focused on fluid-structure interaction [1][2][3][4][5][6][7] studying dynamic stress of tubular pump impeller structure. Furthermore, most research [5][6][7] selects the overall structure of the impeller as a finite element analysis model, which cannot accurately describe the actual pump impeller.…”

“…Nevertheless, few researches have focused on fluid-structure interaction [1][2][3][4][5][6][7] studying dynamic stress of tubular pump impeller structure. Furthermore, most research [5][6][7] selects the overall structure of the impeller as a finite element analysis model, which cannot accurately describe the actual pump impeller. By virtue of CFD software CFX and Ansys Workbench platform, we calculated bidirectional fluidstructure interaction on the impeller blade of a shaft extension tubular pump device, and obtained the numerical distribution of dynamic stress of the impeller blade under different lift conditions.…”

Study into the Improvement of Dynamic Stress Characteristics and Prototype Test of an Impeller Blade of an Axial-Flow Pump Based on Bidirectional Fluid–Structure Interaction

“…Additionally, multiple scholars have studied FSI problems by introducing the immersed boundary method (IBM), which could avoid the numerical instability induced by grid deformation due to FSI [7][8][9][10][11]. Among the current studies on FSI [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17], few are related to the structural dynamic stress of axial-flow pump impellers, and the structural response to the transient fluid-structure interaction (FSI) of axial-flow pump impellers has not been studied in depth. Meanwhile, the overall structure of an impeller has been selected as the research object for finite element analysis in the majority of studies [13][14][15][16][17], which could not show the performance of a real pump impeller accurately.…”