Enhancing the Effective Temporal Resolution of Schlieren Imaging for Unsteady Compressible Flows
Year: 2025
Type: conference-paper
Abstract: The unsteady flow mechanisms that can be extracted from high-speed shadowgraph and schlieren methods in compressible flows are often limited by the maximum frequencies recorded, which are defined by the frame rate of the system camera. This paper proposes a data processing method to enhance the effective temporal resolution of flow visualisation data by taking advantage of camera capabilities to record a sub-region of the domain at frame rates higher than the nominal value. By using proper orthogonal decomposition to integrate some higher-frequency information into the original data set, a time series of schlieren images is reconstructed with increased effective frame rate. The approach is applied to shadowgraph data of a Mach 1.3 underexpanded jet flow recorded at 20,000 frames per second over the entire field of view, with a smaller subdomain recorded at 40,000 frames per second. The reconstruction produces a series of full-domain shadowgraph images at 40,000 frames per second. The cross-correlation coefficient compared to known true values is 0.949, which corresponds to 13% enhancement from typical inter-frame correlations towards perfect reconstruction.
Authors: Langfield, J., Webb, J., Quinn, M. K., Sabnis , K.
Language: English
Subfield: Aerospace Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7112052013
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