Gallagher, Matthew2022-11-142022-11-142022-08https://hdl.handle.net/11299/243046University of Minnesota M.S. thesis. August 2022. Major: Mechanical Engineering. Advisor: Thomas Chase. 1 computer file (PDF); vii, 103 pages.This thesis presents new modeling and design techniques for small displacement proportional pneumatic valves. There are two main contributions of this thesis work. The first is the design and testing of a novel piezoelectric stack-style valve design that increases mass flow capacity compared to prior art. The valve comprises a piezoelectric stack-actuated metallic seat that is capable of metering air at rates greater than 1 g/s while having a leak rate of less than 0.01% of full-scale flow. The second contribution is the development and validation of a piecewise analytical mass flow model for hard planar valve seats and seals. The model provides an accurate continuous solution that transitions from subsonic, rarified, viscous flow at small displacements to sonic, choked, compressible flow at high displacements. The analytical flow models are validated by both numerical computational fluid dynamics and experimental testing.enactuatormicrovalvepiezopiezoelectricpneumaticvalveThesis or Dissertation