Oscillatory Thermal Structures in a Reattaching Jet Flow

Article type: Research Article

Authors: Narayanan, V.

Affiliations: School of Mechanical, Industrial and Manufacturing Engineering, Oregon State University, 204 Rogers Hall, Corvallis, Oregon 97331-6001, USA. E-mail: vinod.narayanan@oregonstate.edu

Abstract: Spatially varying surface temperature oscillations in a nominally steady reattaching slot jet at a Reynolds number (Re) of 5000 are analyzed using Proper Orthogonal Decomposition (POD) for two nozzle-to-surface spacings, and three exit openings of the nozzle. The surface temperature data in these experiments were recorded using infrared thermography at a frequency of 20 Hz along two selected lines on the impingement surface corresponding to geometrically similar and dissimilar regions within the reattachment curtain. The magnitude of temperature oscillations were found to increase with an increase in exit opening for the larger nozzle spacing. The POD analysis results indicate that a majority of the temperature flucutations are well captured by 15 dominant modes. In many cases, the three dominant modes accounted for approximately 60 percent of the variance in surface temperature fluctuation.

Keywords: Infrared (IR) Thermography, thermal structures, reattachment, jet, temperature fluctuations, Proper Orthogonal Decomposition (POD)

Journal: Journal of Visualization, vol. 10, no. 4, pp. 389-396, 2007