The Use of a Coanda Nozzle with Parallel Secondary Injection for the Thrust Vectoring of a Two-Dimensional Compressible Fluid

摘要

An experimental investigation was performed to determine the effect of parallel injection of a secondary fluid on a two-dimensional coanda-effect nozzle used as a thrust vectoring (jet-switching) device. The effect of leakage in the vortex area of a conventional coanda-effect nozzle utilizing perpendicular secondary injection was also determined. The injection of secondary fluid parallel to the centerline of the nozzle caused the primary jet to deflect toward the secondary jet and to attach to the nozzle sidewall nearest the secondary jet. A 1 to 10 decibel drop in the overall noise level resulted when the parallel secondary fluid was injected into the nozzle. Attachment of the primary jet to the nozzle was stable and was sustained by 'coanda-effect' flow in the separation region formed between the primary jet and the wall after secondary injection was discontinued. The wall attachment point was insensitive to increases in pressure ratio; however, the attachment point moved downstream along the nozzle wall as setback ratio increased from 4 to 7.