High-Precision Digital Image Correlation for Investigation of Fluid-Structure Interactions in a Shock Tube
- PDF / 4,472,531 Bytes
- 15 Pages / 595.276 x 790.866 pts Page_size
- 32 Downloads / 201 Views
RESEARCH PAPER
High-Precision Digital Image Correlation for Investigation of Fluid-Structure Interactions in a Shock Tube K.P. Lynch 1
&
E.M.C. Jones 1 & J.L. Wagner 1
Received: 30 September 2019 / Accepted: 18 May 2020 # Sandia National Laboratories 2020
Abstract Background: Structural response measurements are challenging in aerodynamic testing environments due to high-speed requirements, facility vibrations, and the desire for non-intrusive measurements. Objective: This study uses stereo digital image correlation (DIC) to investigate the response of a jointed beam under aerodynamic loading in a shock tube. Methods: The incident shock subjects the beam to an impulsive frontal load followed by periodic transverse loading from vortex shedding. Several considerations necessary to realize high-precision are addressed: first, a hybrid stereo camera calibration accounted for tangential distortions when imaging through thick windows. Second, a measurement bias from Xenon flash-lamp light sources was identified and removed using laser illumination. Third, facility motion was mitigated by vibration isolation and appropriate signal filtering. Finally, aerooptical distortions from turbulence were removed using a low-order reconstruction. Results: The resulting displacement data has a noise floor of approximately ± 1 μm at 20 kHz sampling rate. The reduction of primary noise sources allows a transient structural response on the order of 10–40 μm to be quantified. The highest vibrations occurred when the vortex shedding frequency matched the beam’s natural frequency. Conclusion: the noise reduction techniques described allow for structural measurements requiring high-precision, non-intrusive displacement data to be performed in aerodynamic environments. Keywords Digital image correlation . Shock tube . Fluid structure interaction
Introduction Understanding fluid-structure interactions (FSI) is critical for numerous engineering applications, such as aircraft design, skyscrapers, and bridges, where structures can experience significant vibrations and deformation caused by complex, timedependent fluid environments. A fair amount of FSI work has been conducted in low-speed flows, e.g., [1]; however, data in high-speed, compressible flows (i.e., velocities exceeding approximately 100 m/s) remains scarce. A few examples include the structural response of a store in an aircraft bay [2], panel response under loading imposed by turbulent and transitional boundary layers [3–5], panel response to shock waveElectronic supplementary material The online version of this article (https://doi.org/10.1007/s11340-020-00610-8) contains supplementary material, which is available to authorized users. * K. P. Lynch [email protected] 1
Sandia National Laboratories, Albuquerque, NM, USA
boundary layer interactions [6–8], and panel response to supersonic jets [9, 10]. In the latter cases, attention is often given to large panel displacements, where the structural dynamics become nonlinear [7–11]. An additional challenge of the FSI problem invo
Data Loading...
