Jet impingement heat transfer on dimpled target surfaces

Detailed heat transfer distributions are presented over a jet impingement target surface with dimples. Jet impingement by itself is an extremely effective heat transfer enhancement technique. This study investigates the effect of jet impingement on a target surface with a dimple pattern. The effect of dimple location, underneath the jets or between the jets, is investigated. The effect of dimple depth is also investigated. The average jet Reynolds number is varied from 4800 to 14 800. The heat transfer measurements are obtained using the transient liquid crystal technique. Results for dimpled target surfaces are normalized with data for plane target surfaces to determine whether the presence of dimples enhances heat transfer. Results show that the presence of dimples on the target surface, in-line or staggered with respect to jet location, produce lower heat transfer coefficients than the non-dimpled target surface. The bursting phenomena associated with flow over dimples produces disturbances of the impingement jet structures resulting in lower levels of heat transfer coefficients on the target surface.