The Heat Transfer Performance of Diamond Pins with Coanda Effect on a Heat Sink

A multiple-intersecting flow network, pattern with diamond pins, is common in biological and industrial systems such as the human vascular system, the internal coolant passage of turbine blade inside gas turbine engine, the liquid cooling channel inside electronic modules. An infrared thermovision system is used to map the detail local convective heat transfer coefficients for the multiple-intersection flow network consisting of a 30deg intersection angle. In addition, a digital particle image velocimetry (DPIV) system had been developed to measure instantaneous and ensemble-averaged flow fields in the multiple-intersection flow networks. The flow at each intersection is characterizes by a collision of two flow streams, resulting in vortices on the two sides of the diamond-shaped pin in the post-intersecting region of the network. It is noticed that the vortex at one side increases, at the same time the vortex at the other side decreases with the flip-flop flow at the exit end of the flow network. The study also found the vortex ring places on interlacing surface of the downstream-half of the diamond- shaped pin between the two longitudinal rows. The complex flow patterns are found to play an important part in the local heat transfer performance. The main effort of the present study is attempt to interpret the DPIV measurement results to understand the detailed flow patterns inside the multiple- intersection flow networks and the heat transfer data using an infrared thermovision system.