Acoustic and flow characteristics of cold high speed coaxial jets

The potential of using the coaxial supersonic interacting jets as a jet noise suppression technique was investigated. Extensive experimental investigations of far field noise from model supersonic coaxial cold jets were conducted. These experiments were performed for two and three nozzle arrangements and single convergent underexpanded round and annular jets at a wide range of operating pressure ratios (from pressure ratio 2.63 to 5.12). All nozzles have equal exit area, coplanar exits and finite but thin nozzle lips. Comparison schemes are presented for the overall acoustic power levels produced by coaxial multiple nozzles operated at minimum noise mode of operation.