Performance of the piezo-poppet valve. Part 1

Abstract

The thermofluid mechanics of inflow (flow-to-close) and outflow (flow-to-open) conical poppet head valves is investigated for the range of small and controllable openings made available from the employment of a practical piezo-electric stack driver. A computational fluid dynamics (CFD) package suite is applied to the above task, the results from which are verified experimentally for several outflow slave valve (a valve with a non-electrical stand-in for the piezo stack) poppet lifts, cone angles, and pressure drops for the steady, non-isothermal flow of a test liquid (Tellus R37). Finally, the inflow valve performance is examined and a simple sizing technique consolidated. The results are compared, as far as is possible (quantitatively), with the findings of previous workers. This is done in order further to justify the use of CFD for the design of valves of small but potentially greater displacement than available from the contemporary piezo drivers and to underpin design exercises that are intended to optimize low lift valves for real operating conditions. In a companion paper unsteady/moving boundary and transient flow is tackled using a fast and precise piezo stack to actuate the same poppet head variations (as in the steady state case) as are the effects of manufacturing tolerances on poppet eccentricity, angular misalignment, and seat chamfering for small displacements.