Characterization and Evaluation of PIV Illumination System Using High Power Light Emitting Diodes for WaterTank Applications

摘要

We report on the implementation of the low cost multiple high power light-emitting diodes (HPLEDs) as illumination source for particle image velocimetry measurements in a water tank. The illumination system consists of a custom-built circuit developed using off-the-shelf components for driving the HPLEDs beyond its recommended rating. Two 20 W green LEDs were employed as the pulse illumination light source. The incoherent light generated by the LEDs is channeled into a fiber optic bundle linked to a cylindrical lens for light sheet generation. The light produced by the LEDs was first characterized in term of its wavelength and illuminance properties with respect to input power and pulsing frequency. The complete system was then evaluated by studying the flow around NACA 0018 airfoil in the water tank filled with the seeding particles. The developed system was able to capture the flow field generated by the airfoil when moving at various attack angles. Images acquired using both laser-based and HPLEDs based illumination systems are compared. The results obtained demonstrate the feasibility of the developed low cost HPLED illumination system.