A PIV dynamic velocity range enhancement approach using ROI option of imaging sensors

The ability to interact with the readout mechanism of contemporary image sensors offers new possibilities that can be utilized to improve the performance of digital particle image velocimetry (DPIV) systems. For instance, an intelligent selective region-of-interest (ROI) option can increase the frame rate of a camera, which would allow flow assessment of higher speeds thus ameliorate the dynamic velocity range (DVR) of a DPIV system. However, ROI increases the frame rate by narrowing down the field-of-view (FOV) of the PIV system, which prevents embracing the complete field of flow. To overcome this constraint and maintain the full FOV, we propose a technique, where a fixed height ROI strip is slid over a sensor array and partial flow fields corresponding to each ROI position are obtained. Then, the overall flow field is reconstructed by stitching these partial flow fields. We demonstrate an application of the proposed method by a series of experiments with laminar flows inside a rectangular microchannel. Specifically, we show that by applying the proposed technique the maximum assessable flow velocity by an ordinary DPIV system can be increased at least 4 times without any extra hardware investment.

► We present a method to increase the dynamic velocity range of a DPIV system.
► The method applies only flexible manipulating of a CCD readout mechanism.
► It utilizes the smart selective region-of-interest (ROI) option of modern sensors.
► The method maintains the full field of view by sliding the ROI across the CCD array.
► We validated the proposed technique by measuring laminar flows in microchannels.