Aeroacoustic Investigation of Deployed Spoiler During Steep Approach Landing

Abstract

A steep approach landing procedure utilizes a steeper glide slope, greater than the conventional 3-deg glide angle, in order to alleviate noise on the ground. Spoilers are deployed to slow down the aircraft near to the airport perimeter. Steep approach procedure reduces the noise on the ground by allowing aircraft to fly higher and descend with lower engine ratings than conventional landing approach. In this paper for the first time a computational aeroacoustic investigation is carried out on a two-dimensional high lift system in a steep approach landing configuration in order to identify the noise impact of a deployed spoiler. The high lift model is at an angle of attack of 5-deg with the slat and the ap deployed at 30-deg and 38-deg respectively. The spoiler is deployed at an angle of 20-deg. The freestream Mach number is M1 = 0:235, corresponding to a Reynolds number Re = 5:47 106. Hybrid methodology involving Computational Fluid Dynamics and Ffowcs-Williams and Hawking integral method is used to predict far field noise. The results so far show that a deployed spoiler drastically changes the flow field around the high lift devices. The slat cove vortex grows in size and the flow separates early from the ap surface forming a much wider wake. Contours of fluctuating pressure show noise radiation from the slat cove region and the spoiler trailing edge.