A kilohertz frame rate cinemagraphic PIV system for laboratory-scale turbulent and unsteady flows |
| |
Authors: | A Upatnieks K Laberteaux SL |
| |
Institution: | (1) Department of Aerospace Engineering University of Michigan Ann Arbor MI 48109-2140, USA, US;(2) Department of Mechanical Engineering University of Michigan Ann Arbor MI 48109-2125, USA, US |
| |
Abstract: | A kilohertz frame rate cinemagraphic particle image velocimetry (PIV) system has been developed for acquiring time-resolved
image sequences of laboratory-scale gas and liquid-phase turbulent flows. Up to 8000 instantaneous PIV images per second are
obtained, with sequence lengths exceeding 4000 images. The two-frame cross-correlation method employed precludes directional
ambiguity and has a higher signal-to-noise ratio than single-frame autocorrelation or cross-correlation methods, facilitating
acquisition of long uninterrupted sequences of valid PIV images. Low and high velocities can be measured simultaneously with
similar accuracy by adaptively cross-correlating images with the appropriate time delay. Seed particle illumination is provided
by two frequency-doubled Nd:YAG lasers producing Q-switched pulses at the camera frame rate. PIV images are acquired using
a 16 mm high-speed rotating prism camera. Frame-to-frame registration is accomplished by imaging two pairs of crossed lines
onto each frame and aligning the digitized image sequence to these markers using image processing algorithms. No flow disturbance
is created by the markers because only their image is projected to the PIV imaging plane, with the physical projection device
residing outside the flow field. The frame-to-frame alignment uncertainty contributes 2% to the overall velocity measurement
uncertainty, which is otherwise comparable to similar film-based PIV methods.
Received: 11 July 2000 / Accepted: 21 June 2001 Published online: 29 November 2001 |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|