On the hydrodynamic characterization of a passive Shape Memory Alloy valve

Abstract An attractive approach to the thermal management of next generation photonics devices (heat fluxes > 10 2  W/cm 2 ) is micro-channel cooling, and micro-valves will be required for refined flow control in the supporting micro-fluidic systems. In this paper, a NiTi Shape Memory Alloy (SMA) micro-valve design for passive flow control and thermal management was prototyped at the macro scale and hydrodynamically characterized. The dynamic behavior of the valve was observed and the loss coefficient ( ζ v ) derived from pressure-flow measurements. The hydrodynamic characterization study is important because ζ v is sensitive to Re and geometry in the flow regime of the micro-fluidic system. Static replicas of the SMA valve geometry were tested for low Re (110–220) and a range of opening ratios ( β ) in a o1 mm miniature channel. The loss coefficients were found to be sensitive to flow rate and decreased rapidly with an increase in Re . A correlation was developed to interpolate ζ v from a given Re and β . The valve loss coefficients obtained in this work are important parameters in the modeling and design of future micro-fluidic cooling systems.

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