Turbulent Heat Transfer in a Forced and Unforced Two Dimensional Air Jet Impinging on an Isoflux Surface

Abstract

Mean heat transfer and flow characteristics of a two-dimensional air jet impinging on a uniform heat flux surface were investigated. Measurements were made in a steady unforced jet, and in a jet with externally introduced forcing. The jet issued from a 24:1 aspect ratio rectangular nozzle. The heat transfer characteristics are parameterized by jet Reynolds number based on the hydraulic diameter and on the nozzle-to-plate spacing. Flow conditions (mean, turbulent fluctuations and power spectra) exiting the jet were measured and used to interpret their influences on the stagnation point heat transfer. A comparison of an unforced impinging jet to a forced impinging jet showed enhancements in the heat transfer rate of up to 57% with forcing.