Study of temperature effect on flow and acoustic behavior of supersonic jets emanating from a faceted nozzle

Abstract

An experimental and numerical investigation is conducted on a supersonic jet issuing from a converging diverging faceted nozzle for various jet temperatures. This investigation aims to shed light on the associated flow field and acoustic signatures of the aforementioned jet. The work presented here is part of a continuous effort to better understand the noise generation mechanisms associated with tactical aircraft jet nozzles. For this reason, two faceted nozzles design to match the specifications of a F400 series nozzle were fabricated and tested. Flat surfaces and sharp corners in the interior geometry of faceted nozzles introduce the generation of shock waves and associated Mach disks that characterize the jets emanating from this type of nozzles. In this study, two scaled nozzles with equivalent exit diameters of 1.45” and 3.17” were used to investigate the temperature effects on flow and acoustics of the supersonic jet at overexpanded conditions. The experimental methods employed were Particle Image Velocimetry (PIV) and farfield acoustic measurements. In addition, LES simulations provided by the Naval Research Laboratory (NRL) show good agreement with experimental results for both flow and acoustic measurements.