Color-coded smoke PIV for wind tunnel experiments improved by eliminating optical and digital color contamination

A single-camera color particle image velocimetry (PIV) system that can acquire the PIV data of three separated layers has been redesigned to make it more suitable for wind tunnel applications. We target smoke images that have particle-per-pixel values higher than unity. The system consists of a high-power color-coding illuminator and a digital color high-speed video camera. RGB values in the recorded image include severe color contaminations due to five optical and digital sequences. To quantify this, a snapshot calibration method is proposed to describe the contamination matrix equation. Taking the inverse matrix allows the in-plane PIV in each color layer to be accurately implemented. We also derive the mathematical limits in the operation of colored smoke PIV, which are explained by the matrix properties. The feasibility of the proposed method was demonstrated by application to a turbulent wake behind a delta wing at a quasi-stall angle of attack.

Automated summary

A single-camera color PIV system has been redesigned for wind tunnel applications to capture PIV data of three layers with smoke images of particle-per-pixel values above unity. A snapshot calibration method was proposed to quantify color contaminations in RGB values, allowing accurate in-plane PIV in each color layer. The feasibility was demonstrated in a turbulent wake behind a delta wing at a quasi-stall angle of attack.