Measurement methods fusion and application for fluid-structure coupling analysis using TSP and deformation detection techniques; Fusion von Messmethoden und deren Anwendung für die Analyse der Fluid-Struktur-Kopplung mittels TSP undVerformungserkennungstechniken

Abstract

Flow-structure coupling analysis is the study of fluid flow causing deformation of a surface or structure. Several optical measurement techniques exist to extract position and deformation information of the surface. A combination of deformation measurement and Particle Image Velocimetry (PIV) has been applied with success in recent years. In this work the combination of surface measurement with spatial TSP and the simultaneous measurement of the position/deformation using Image Pattern Correlation Technique (IPCT) is evaluated. Given constraints such as limited space in the wind tunnel and the need for cost-efficient setups, there is a keen interest in minimizing the number of high-speed (HS) cameras used. Consequently, two distinct measurement systems are proposed for integrating TSP and IPCT: The first system examines event-based (EV) cameras, a novel, cost-efficient, compact and lightweight technology as an alternative to frame-based HS cameras for the deformation detection with IPCT. EV cameras are human retina inspired sensors, that can only register brightness changes. The EV cameras are used in combination with a green LED that operates in pulsed mode, projecting a random dot pattern onto the blade. Deformation calculation is performed through preceding triangulation of the model. For comparison purposes a HS camera imaging system for deformation detection is incorporated, and the resulting error of the EV and HS measurement system is investigated. For simultaneous TSP measurement a blade coated with TSP, an UV LED and one HS camera is used. The timing and synchronization of the IPCT system and TSP system is optimized. The second system proposes to use a state-of-the-art IPCT setup, consisting of two stereoscopic HS cameras and a fixed dot pattern on the blade, for simultaneous IPCT deformation detection and TSP measurement. Combinations of the mentioned measurement techniques are upcoming challenges and are more and more interesting to understand the flow physics and correlation to the deformations/positions. The investigated measurement techniques are applied on a wind tunnel model, which is investigated in a low-speed wind tunnel facility (1MG low speed wind tunnel Göttingen).