An Experimental Investigation on Impinging Jets Using Visualisation Methods

Impinging jets are used in many applications for cooling or heating systems, for example cooling gas turbine blades. The jet impact on a surface and the interaction between the jet and the flow determine a complex flow field which leads to a high heat transfer coefficient. The study of this flow field is thus very important. An experimental flow visualisation study has been conducted using several techniques (smoke technique, oil and pigment and the thermotropic liquid crystal technique) to determine the flow pattern for a row and a system of jets impinging on a flat plate with subsonic velocity. Some secondary vortexes are shown, thus allowing the heat transfer coefficient distribution to be understood. © 1999 Editions scientifiques et m~dicales Elsevier SAS