Studying the effect of flap angle on the noise of interaction of a high-bypass jet with a swept wing in a co-flow

Jet-flap interaction noise for a small-scale swept wing model of a trendsetter plane has been studied experimentally, with a double-stream nozzle installed nearby. The effect of the flap angle on the noise of jet-wing interaction has been analyzed. It has been discovered that the flap angle considerably affects the interaction noise in a wide frequency range in such a way that the noise intensity in each frequency band grows exponentially as the flap edge approaches the shear-layer boundary (on a logarithmic scale, this corresponds to linear scaling of the spectrum depending on the flap angle). The exponential noise reduction as the flap angle decreases agrees with the known theoretical simplified-configuration models that are based on the effect of interaction of the near field of instability wave with the edge. Not only does this agreement show that noise increase/reduction mechanism may be associated with similar processes, it also provides an effective tool for controlling the interaction noise.