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In this paper, we present a method of quantitatively measuring in real-time the dynamic temperature field change and visualization of volumetric temperature fields generated by a 2D axial-symmetric heated fluid from a pulsatile jet in a water tank through off-axis digital holographic interferometry. A Mach-Zehnder interferometer on portable platform was built for the experimental investigation. The pulsatile jet was submerged in a water tank and fed with water with higher temperature. Tomographic approach was used to reconstruct the temperature fields through the Abel Transform and the filtered back-projection. Averaged results, tomographic view, standard deviation and errors are presented. The presented results reveal digital holographic interferometry as a powerful technique to visualize temperature fields in flowing liquids and gases.

This paper presents a very effective interference technique for the sensing and researching of compressible fluid flow in a wind tunnel facility. The developed technique is very sensitive and accurate, yet easy to use under conditions typical for aerodynamic labs, and will be used for the nonintrusive investigation of flutter in blade cascades. The interferometer employs a high-speed camera, fiber optics, and available “of-the-shelf” optics and optomechanics. The construction of the interferometer together with the fiber optics ensures the high compactness and portability of the system. Moreover, single-shot quantitative data processing based on introducing a spatial carrier frequency and Fourier analysis allows for almost real-time quantitative processing. As a validation case, the interferometric system was successfully applied in the research of supersonic compressible fluid discharge from a narrow channel in a wind tunnel. Density distributions were quantitatively analyzed with the spatial resolution of about 50 μm. The results of the measurement revealed important features of the flow pattern. Moreover, the measurement results were compared with Computational Fluid Dynamics (CFD) simulations with a good agreement.