Experimental aeroelastic characterization based on integrated optical measurements

Abstract

This thesis presents a novel measurement approach for aeroelastic wind tunnel testing. The key novelty of this approach is the integrated measurement of aerodynamic and structural quantities using an optical technique. The considered approach consists of combined measurements of flow tracer particles and structural markers using a Lagrangian particle tracking system. Based on these measurements, the quantities of interest for the characterization of an aeroelastic interaction, which are the three forces in Collar’s triangle (aerodynamic, elastic, and inertial), are determined. Currently, measurements in aeroelastic wind tunnel tests are typically performed with individual sensors for each quantity of interest (pressure transducers, strain gauges, or accelerometers) that are installed inside the experimental model and/or with a force balance that measures the total loads acting on the model. The integrated optical measurement approach is an advancement over this existing measurement technology because it provides field measurements of the aeroelastic structural response and the unsteady flow field around the experimental model, based on which the aerodynamic and structural load distributions can be determined, without requiring an instrumentation of the model with sensors. This measurement approach is therefore an effective way to produce experimental reference data to support the development of novel aeroelastic prediction methods with a potential to accelerate the technological development process for innovations in aeronautics in the future. The development and applications of the integrated optical measurement in this thesis are based on the measurements that were performed in three experimental campaigns in the wind tunnel. Each of the three experiments corresponds to one of the three main chapters of this thesis. All three experiments are performed on a largemodel scale, with dimensions on the order of 1m, which is a scale of high practical relevance for aeroelastic wind tunnel testing. The complexity of the three experiments, in terms of the aeroelastic phenomena that are observed, is increased incrementally, from a rigid-body motion, over a linear aeroelastic test case, to a nonlinear aeroelastic test case. Based on the observations and findings of the previous experiments, the data analysis methods for the subsequent experiments are selected and applied. The first measurements with the integrated approach...