Ni-based microvalves for flow modulation: Toward active combustion control

We report on the development of nickel-based micro diaphragms for fuel flow modulation during jet engine combustion. The micro diaphragms were fabricated and assembled, after which they were tested in a prototype mesoscale fuel injector. A combination of deep reactive etching, silicon loss molding, electroplating, and conventional machining techniques were utilized to implement the mesoscale fuel injector and the nickel diaphragms. Modulation of fluid flow through the fuel injector was demonstrated with the nickel diaphragm functioning as a valve. The diaphragms were characterized and the measured results were compared with results from finite element analysis. The fuel injector was characterized for flow rate versus applied fluid pressure and these results were compared with computational fluid dynamics results. The primary goal of this work is to demonstrate the concept of flow modulation using a nickel-based diaphragm, with future generations planned to be implemented in silicon carbide. Future application of this technology will be in active combustion control to mitigate combustion instabilities in jet engines when they occur.