EFFECT OF VALVE PORT GAS INERTIA ON VALVE DYNAMICS - PART I: SIMULATION OF A POPPET VALVE

摘要

A theoretical model was developed of the nonlinear dynamic response of a reciprocating air compressor discharge valve system considering unsteady flow. It constitutes an extension of previous modeling procedures where the flow was considered in a quasi steady manner. The most simplified valve system was used which consists of a mechanical spring loaded circular disc valve centered over a single circular orifice. Coupled unsteady nonlinear flow and disc valve motion equations were developed by treating the flow by a sequence of finite control volumes. Unsteady continuity and momentum equations were written for each control volume. The flow in the orifice, valve passage and piston cylinder was modeled as compressible. Contraction coefficients were incorporated to account for streamline effects. The Kirchoff contraction coefficient was assumed in the orifice area, while the entrance and exit discharge coefficients in the disc valve passage are assumed from experimental flow-force data. Viscosity was included between the disc valve and seat.