Application of pulsed high-power LEDs for high speed visualization and measurement of flows

Abstract

The rapid progress in the light emitting diode (LED) manufacturing technology nowadays enables the application of high-power LEDs as light sources for both high-speed videography and flow velocimetry. These devices have a number of attractive advantages in comparison to lasers and xenon illumination. Aside from the dramatically reduced cost of procurement, relatively simple operation and considerably longer life time, LEDs are very stable in terms of intensity and their spatial distributions providing incoherent illumination free of speckle artefacts. The presentation describes the use of pulsed hight power LEDs for high-speed Schlieren videography, high speed particle image velocimetry (PIV) as well as tomographic PIV. Pulsed LED illumination is also well suited for surface deformation measurement techniques such as image pattern correlation technique (IPCT) or projected pattern correlation technique (PROPAC). Future developments will result in LED devices with even higher light emission opening a wider range of application in imaging flow diagnostics.