PSI - Issue 17

Pedro J. Sousa et al. / Procedia Structural Integrity 17 (2019) 812–821 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

813

2

1. Introduction

In fields such as transportation and energy generation, rotating structures are central for the operation of several widespread devices. In several of these cases, for example wind turbines and aeronautics, the employed rotating structures are long and slender, and exhibit large deformations in operation [1 – 3]. In recent years, the analysis of rotating structures has been approached using both numeric and experimental approaches, especially concerning wind power and aeronautics [3 – 9]. It is well-known that the shape of the blades influences the airflow, which in turn affects the loads applied to the blades and, consequently, their displacement. As such, it is important to predict and measure the displacements suffered by such blades, in order to improve their efficiency and reduce noise generation. The main objective of this work is to compare experimental measurements obtained using digital image correlation applied to rotating objects as described in [8 – 10] with numerical results obtained using Fluid-Structure Interaction in a Computer Fluid Dynamics – Finite Element Analysis coupled model. First, a short overview of the experimental approach and the experimental results are provided in section 2. Then, the computational model is detailed, including the methods used for the acquisition of the necessary material properties and the obtained results. Finally, a discussion regarding their differences is provided where the most significant ones are analyzed.

Nomenclature CFD

Computer Fluid Dynamics Digital Image Correlation Finite Element Method Fluid-Structure Interaction

DIC FEM

FSI

2. Experimental Approach

The experimental results were obtained using the methodology described in [8, 9]. It uses a trigger controller that synchronizes the rotational motion with a pair of high-speed cameras with fast shutters (approximately one microsecond) to obtain stereo images of the measurement target. Afterwards, the images are processed using Digital Image Correlation, for which it is necessary to paint a speckle pattern on the target. The data obtained from DIC is then processed using a custom algorithm [8] to remove rigid rotations and align the measurement axes with the geometry. The setup is schematized in Fig. 1, where the different parts and their relationships are shown. The measurement directions X and Z are also shown, while the Y direction follows a right-handed coordinate system.