Stagnation Region Heat Transfer for Circular Jets Impinging on a Flat Plate

Abstract

The heat transfer characteristics in a stagnation region were investigated experimentally for five circular free jets impinging into a heated flat plate. The local temperature distributions are estimated from the thermal images obtained from an infrared camera. To get a precise heat transfer data over the plate, fully developed straight pipe jets were used in this study. Mean jet Reynolds number varied from 1,000 to 45,000, jet-to-plate vertical non-dimensional distance H/D varied from 2 to 6, and the spacing distance jet-to-jet S/D varied from 2 to 8. A geometrical arrangement of one jet surrounded by four jets an in-line array was tested. The results show that the stagnation point Nusselt number is correlated to a jet Reynolds number as Nu_st∝Re^0.61. The average Nusselt number is higher at a separation distance of 2D for three cases of spacing distances, S/D = 2, 4, and 6.

Keywords::

• stagnation point
• multiple jets
• heat transfer
• turbulent intensity

Acknowledgments

These experimental results would not have been possible without the support of the staff of ISUT, Magdeburg, Germany.

Notes

Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/ueht