Performance of the piezo-poppet valve. Part 2

Abstract

In a companion paper the piezo-poppet (PZP) valve was examined for its operational flexibility principally in the steady outflow (flow-to-open) and to a lesser extent inflow (flow-to-close) conical head 90° seat configurations. Outflow form experimental results were used partially to verify a computational fluid dynamics (CFD) analysis of the situation and to substantiate a basis for a simple sizing technique. The present paper goes on from that juncture by using CFD to investigate the tolerancing problems on the low-lift PZP valve in respect of deviations of the centre-line of the poppet from that of its inlet port and of the modification of the seat itself - by chamfering. Finally, the unsteady performance of the arrangement is computed, for standardized conditions, to give an assessment of control performance when the poppet is (a) theoretically adjusted quickly at the same pressure drop or (b) hypothetically experiences a pressure surge. In (a) the CFD is verified by experiment. From these tasks arise the prospect of innovative non-isothermal, unsteady flow modelling of hydraulic devices employing moving orthogonal boundaries, and three-dimensional CFD analysis. All of these tasks were performed on the outflow valve.