EPTT 2020

12th Spring School on Transition and Turbulence

COMPENSATION OF IMAGE DISTORTION ON PIV MEASUREMENTS OF A STIRRED TANK

Submission Author: Jenniffer Solange Ayala , SP
Co-Authors: Aliandra Barbutti, Aline Gallo De Mitri, Jenniffer Solange Ayala , Rodrigo de Lima Amaral, Helder Moura, José Roberto Nunhez, Guilherme Castilho
Presenter: Aliandra Barbutti

doi://10.26678/ABCM.EPTT2020.EPT20-0101

 

Abstract

Particle image velocimetry (PIV) measurements are increasingly common in the investigation of turbulent flow parameters for the optimization of stirred tanks. Generally, PIV applications are performed using the camera’s position perpendicular to the light plane. In some cases, the use of tilted images is the most suitable when optical access is limited. In addition, the curvature of the tank also changes the relationship between the physical space and the image plane, causing distortions. These can be compensated in the physical space using a wedge around the tank, for example, but it is often expensive or unfeasible in the experimental arrangement. In the image plane, a third-order polynomial function can be used to correct the distortion effect from a calibration procedure. However, this global function could fail in regions with high distortions. This work aims to investigate the performance of the image distortion compensation on PIV measurements of a stirred tank without a wedge around it. Two cameras with different positions were used to simultaneously record a calibration target, in order to obtain a polynomial function from a calibration procedure in one and two steps (multicalibration). This approach has shown promising for the camera positioned with the smallest angular displacement in relation to the object plane. The best configuration was then applied to evaluate turbulent kinetic energy (TKE) distribution. However, the calibration and the multicalibration did not present significant differences, and both were considered adequate in the analysis of stirred tanks.

Keywords

Image Distortion Compensation, TANK, PIV, Turbulent kinetic energy

 

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