Thermal management for the future generations of electronics faces challenges including total heat dissipations exceeding 100 W and local hotspots resulting from non-uniform heating. This work develops microchannel heat sinks with cross-linked channels to achieve a better chip temperature uniformity under non-uniform heating conditions. Stream-wise microchannels with a hydraulic diameter of 420 μm are subjected to pressure driven water flow. Channel cross-links with a hydraulic diameter of 150 μm, under non-uniform heating conditions, allow fluid lateral transport between the stream-wise channels in the region receiving the largest heat flux and those on the rest of the chip. As a result, a better chip temperature uniformity is achieved by utilizing the local pressure difference and capillary effect. Experimental results with a localized heating condition demonstrate an improvement of approximately 10% in the ratio of temperature of the heater to that of the rest of the chip. Analysis suggests that greater improvement can be achieved through optimization of the dimensions of the cross-links with respect to those of the stream-wise channels and through tailoring more cross-links within the hotspot region.
In the present study, self-sustained shear layer oscillations over shallow, open cavities beneath a low speed, subsonic, laminar boundary layer were studied experimentally in a wind tunnel. The cavities were rectangular in cross-section. The research concentrated upon determining the effects upon cavity resonance of rotating the leading edge of the cavity away from normal to the flow direction. Cavity resonance was identified through spectra of flow fluctuations sensed with hot wire anemometer probes. The resonance frequency was found to decrease gradually as the cavity leading edge was rotated up to 30 degrees from normal to the flow. Nomenclature D cavitydepth(m) L cavity length (m) L' U W effective stream wise cavity length, L/Cos a (m) .-./ St s t r o u~ number (W or ~L'/u) mean free stream velocity in direction x (ds) spanwise width of the cavity (m) f frequencyW) n x streamwise coordinate (m) y transverse ooordinate (m) a 0 h disturbance wave length (m) w angular frequency (radiands) mode of oscillation, n = 1,2, 3 . .angle of cavity rotation from normal (degrees) boundary layer momentum thickness at the cavity leading edge (m)
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