AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
New Detection Method of Filter Leak using the Schlieren Shadow-graph Technique
SHIGERU KIMOTO, Lin Li, Joseph Peterson, David Pui, University of Minnesota
Abstract Number: 770 Working Group: Instrumentation and Methods
Abstract There are several detection methods for filter leak (e.g., scanning, fluorescence, particle image velocimetry, thermal imaging, etc). For aerosol related methods, particles passing through the leakage at the filter can be detected by a scanning probe connected to a particle counter to locate the leakage, or by Particle image velocimetry (PIV), obtaining the flow speed and direction using the scattered light from particles. In the fluorescence detection, a UV light source is used to examine the filter bags for leaks, and wherever there is a leak, the tracer powder will glow brightly under the detector lamp. However, the aerosol methods are usually time consuming and particles are loaded on the filter, which is avoided in some applications and test environment. The imaging methods, e.g. thermal imaging using infrared radiation to form an image and Schlieren shadow-graph technique, have the advantage of visibility, quick response, simplicity and prevention of particle loading.
In this study, we use the Schlieren shadow-graph technique for filter leak detection. Schlieren technique uses light from a single collimated source shining on or from behind a target object (the space downstream of the filter). Variations in refractive index caused by density gradients in the fluid distort the collimated light beam, creating a spatial variation of light intensity, which can be visualized directly. Filters with different pinhole sizes are evaluated and the detail results will be presented in the conference.