The effect of swirl on the annular flow past an axisymmetric poppet valve

Abstract This paper describes an experimental investigation of the swirling flow through an axisymmetric port and poppet valve assembly under steady flow conditions. This work is an extension of the preceding paper, which is a study of the non-swirling flow in the same flow configuration [1]. Three different swirl rates were investigated with the aim to study the effects of swirl on the mean flow and turbulence characteristics of the flow field. The flow structure was studied by means of laser sheet flow visualization and the three velocity components and the associated Reynolds stresses were measured by ensemble-averaged laser Doppler anemometry techniques. The results are compared with those obtained with the non-swirling flow. The addition of the swirl was found to alter the flow structure, particularly below the valve where a new counter-rotating vortex is formed. A toroidal recirculation zone is also formed in the valve passage. The growth and entrainment of the jet emanating from the valve gap increase and its trajectory angle changes. The flow visualization studies showed evidence of precession of the swirl centre and jet flapping. Swirl increases the Reynolds stresses and the turbulence production rate in most regions of the flow.