PIV Measurements of Air Flow Velocity Profile in Microchannels

The knowledge of the flow field in the microchannels of the ionic wind pump and other microscale heat removal devices for electronic components is important. The understanding of the flow field will lead to more effective and improved designs. Non-intrusive particle image velocimetry (PIV) utilizing microscopic objective lens is utilized to obtain the velocity field in microchannels of scales similar to those encountered in such devices. Microchannels with dimensions ranging from 0.8 mm to 2 mm are used, along with an open-channel design. The flow rate of air is held constant for the duration of each experiment and olive oil droplets (0.5 to 1.0 micrometer diameter) are used as the seed particles. Computational fluid dynamics (CFD) models are used to replicate each test. ANSYS Fluent code is used for the computational investigations. The CFD flow fields are compared with the PIV results for validation purposes. Velocity profile information is obtained at three locations along each channel: 20%, 50%, and 80% of the channel length. Experiments are conducted on three 2 mm long channels. The cross-sections (depth and width) are 1 mm × 2 mm, 1 mm × 1 mm and 0.8 mm × 2 mm. The CFD flow fields are compared with the PIV results for validation purposes, with relative errors between CFD and PIV typically between 2% and 10%. The agreement between the PIV data and computational results validate this method.