Landing Gear Noise Reduction by Double Jet Air Curtain Configuration

The complicated shape of aircraft landing gears results in strong turbulent noise and has been the recent focus towards airframe noise reduction. An air curtain can be applied to add a blowing jet to deflect the incoming upstream flow speed around the landing gear to reduce its aerodynamic noise. However, the impact between the incoming airflow and the air curtain can be a new source of noise. Therefore, a double-jet air curtain was proposed. In this study, two rods were chosen to be the bluff body noise source, so as to experimentally study the feasibility of noise reduction by a double-jet configuration curtain application. Specifically, a secondary air curtain with lower velocity was set upstream to the primary one. Flow visualizations were chosen to define the noise source setup. Noise spectra of single-jet configuration firmly validated that air curtain can notably reduce the test body noise. However, the air curtain generates noise at some frequencies. For the double-jet configuration, the spectral analysis proved that the secondary air curtain contributes to reduce the noise due to the impact of the primary air curtain and the upstream flow. But it causes some noise in frequency range of over 10 kHz. However, this noise is much lower than the single-jet configuration. This verified the superiority of double-jet configuration to reduce the landing gear noise. In addition, some further study was proposed.