THE EFFECT OF SWIRL ON THE ANNULAR-FLOW PAST AN AXISYMMETRICAL POPPETVALVE

This paper describes an experimental investigation of the swirling Bow through an axisymmetric port and poppet valve assembly under steady f low conditions. This work is an extension of the preceding paper, whic h is a study of the non-swirling flow in the same flow configuration [ 1]. Three different swirl rates were investigated with the aim to stud y the effects of swirl on the mean Bow and turbulence characteristics of the flow field. The flow structure was studied by means of laser sh eet Bow visualization and the three velocity components and the associ ated Reynolds stresses were measured by ensemble-averaged laser Dopple r anemometry techniques. The results are compared with those obtained with the non-swirling flow. The addition of the swirl was found to alt er the flow structure, particularly below the valve where a new counte r-rotating vortex is formed. A toroidal recirculation zone is also for med in the valve passage. The growth and entrainment of the jet emanat ing 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.