Avaliação numérica da influência do afastamento entre discos de difusores radiais modificados nos parâmetros globais do escoamento

Abstract

With their high applicability in residential and industrial refrigeration systems, reed-type auto- matic valves play a decisive role in the energy efficiency of reciprocating compressors. Due to the complexity of fluid-structure interaction and experimental difficulties imposed by small dimensions, numerical modeling of these components is often performed using the geometric simplification of radial diffusers. This work presents a detailed numerical analysis of the global flow parameters in a modified radial diffuser, characterized by the introduction of a 23° chamfer at the feeding orifice, aiming to evaluate the impact of this geometry on fluid dynamic behavior. Simulations were conducted for different disc spacings (s/d ranging from 0.2 to 1.0) under a fixed Reynolds number (Re = 3000). For the flow field solution, OpenFOAM® software based on the Finite Volume Method (FVM) was used, employing the RNG - turbulence model to close the Reynolds-Averaged Navier-Stokes (RANS) equations. The results demonstrate that the geometric modification smooths the transition from axial to radial flow, significantly altering the pressure profiles on the valve surface. It was observed that, compared to the standard geometry, the chamfered diffuser presents a reduction in the effective force area due to lower pressurization in the central region, alongside an increase in the discharge coefficient, indicating a reduction in pressure losses due to separation at the gap inlet.