An improved method for enhancing the resolution of conventional double-exposure single-frame particle image velocimetry

• Published in: Experiments in fluids Vol. 26; no. 6; pp. 497 - 504
• Main Authors: REHM, J. E, CLEMENS, N. T
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01.05.1999; Berlin
• Subjects: Applied sciences; Chemically reactive flows; Combustion of gaseous fuels; Combustion. Flame; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fluid dynamics; Fundamental areas of phenomenology (including applications); Instrumentation for fluid dynamics; Physics; Reactive, radiative, or nonequilibrium flows; Theoretical studies. Data and constants. Metering; Cross correlations; Turbulent flame; Particle tracking velocimetry; Measurement errors; Algorithms; Double exposure method; Reacting flow; Particle image velocimetry; Velocity measurement
• ISSN: 0723-4864; 1432-1114
• DOI: 10.1007/s003480050316

An improved hybrid particle image velocimetry (PIV)/particle tracking velocimetry technique is presented. The method uses a conventional autocorrelation for a predictor step followed by local cross-correlations of individual particles to obtain individual particle pair displacements within a double-exposed single-frame image. Simulated particle fields are used to demonstrate the improved tracking success (better than 90 percent, even in very dense particle fields) and accuracy of the technique as compared to an existing single-frame hybrid method. In addition, the number of erroneous measured pairs is reduced. The improved success is attributed to the ability of the algorithm to differentiate between overlapped particles and the criteria for correctly identifying overlapped particles are presented. As a check on the effect on derived quantities, computed values before and after resolution enhancement from a real image with constant vorticity and dilatation are presented. The application of this method to a turbulent nonpremixed flame shows about a factor of six increase in the resolution over conventional PIV. (Author)