Experimental investigation of turbulent flow field associated with round and chevron nozzles

Abstract

The turbulent jet is one the main sources of noise in aircrafts. In spite of decades of research, this problem remains a challenging topic in aeroacoustics while the mechanisms of sound generation are not yet fully understood. Modelling of the generation and propagation of sound in a jet generally requires knowledge of turbulence statistics that are not trivially measured, in addition to the mean-velocity field. This paper presents hot-wire measurements of the flow field of a cold, subsonic jet. A comparison is made between the flows generated by two nozzle geometries: a circular and a chevron nozzle. Several jet properties are assessed, such as potential core length, turbulence profiles and one-point two-time velocity correlations. The purpose of these measurements is to study the modifications in the flow field brought about by the chevron nozzle which could be related to modifications in the acoustic field and the noise spectrum.