An Investigation of Noise Reduction for the 3BB Nozzle with a Pylon Using External Flaps

Flaps (or half wedges) attached to the sides of a pylon are shown to result in a small but clear noise benefit. Noise radiated towards the ground is reduced apparently through a deflection and thickening of the fan stream underneath. Based on results from the current as well as concurrent investigations at the University of California at Irvine, it is recommended that further tests in a larger facility simulating realistic engine conditions be considered.