2019 Volume 62 Issue 3 Pages 117-124
Experiments and numerical analyses were conducted to investigate the reflection and shielding effects of jet noise by a horizontal tail and an aft-mounted engine. An acoustic test using a cold jet at a Mach number of 0.98 was carried out with a 28.8-mm-diameter exhaust nozzle and a T-tail model. The effects of the position and angle of the horizontal tail were investigated using the boundary element method and a fitted jet noise source model. The experimental results showed that the sound pressure level increased by 1.5 dB in the downward direction of the aircraft at a Strouhal number of 0.94. The numerical analysis results showed that the reflection effect was highly dependent on the relative position and size of the horizontal tail, the location of the source, and the angle of the horizontal tail. In addition, the effect of the reflected direction was ascertained to find an appropriate horizontal tail and engine arrangement that reduces noise. It was found that the greatest influence in terms of the effective perceived noise level occurred when the reflected direction was 60° from the jet axis.