International Journal of Engineering Applied Sciences and Technology, 2021 Vol. 6, Issue 3, ISSN No. 2455-2143, Pages 6-19 Published Online July 2021 in IJEAST (http://www.ijeast.com) 6 A BRIEF REVIEW ON VARIOUS NOISE REDUCTION TECHNIQUES EMANATING FROM WINGS OF AN AIRCRAFT Oyeniran Noah D. Division of Mechanical and Aerospace Engineering Hokkaido University, Sapporo, Hokkaido, Japan Abstract— One of the challenges and a point of need in the aviation industry is the problem of high level of noise emanation. There are various sources of noise emanating from aircraft which are the noises from engine and airframe including the wings. Noise from the wing is an important phenomenon to be put into consideration as it contributes significantly to the noise emanating from aircraft especially during take-off and landing. Airfoil noise emission emanate on the wing section of an aircraft due to the interaction of the airfoil turbulent boundary layer with the sharp leading edge. Noise reduction then becomes a thing of concern for many engineers and researchers who took it upon their shoulder the responsibility of coming up with design that can help reduce noise emanating from aircrafts to mitigate the noise. Due to this, many researchers have focused on reducing the noise emanating from the aircraft through various means and approaches which include theoretical, computational, and experimental analysis. In a means of compiling and making available a brief review of such work, for easy and quick access necessitate the need of this work. This paper focused on giving a summary and review of different work done by past and current researchers in the field. The review was based on selected current papers on the cutting-edge technology towards enhancing aerodynamic performance of the wing of aircraft and reduction of noise emanating from it. Although fruitful results have been achieved in the aerodynamic noise control, but only little work has been done to summarize the main findings and progresses in this area. This work focused on review of work carried out by many researchers in this area which involves various techniques and attempts ranging from leading edge serration, trailing edge serration, active flow actuation, flexible wing using theoretical, computational, and experimental approach etc. Additionally, some suggestions were made towards further study and improvement in this field of study. Keywords— Trailing Edge Serration, Leading Edge Serration, Leading Edge High Lift Devices, Aerodynamic Performance I. INTRODUCTION The aviation transport industry keeps growing and likewise the population of people around the world keeps growing and of such buildings have keep growing even around major airports. Most airports around the world now are being surrounded by many households who live around the airports. Airport transportation management were left with no choice but to make policy that will make airport environment and surrounding conducive for living. This necessitates a policy that was geared towards reducing the noise coming from the airport activities. Noise reduction then becomes a thing of concern for many engineers and researchers who took it upon their shoulder the responsibility of coming up with design that can help reduce noise emanating from aircrafts so as to mitigate the noise. This paper is based on many research and findings of various researchers towards solving the noise coming out from aircraft wings and also towards improvement of aerodynamics performance. Noises from aircrafts come from two major sources which are the engine and the airframe [1, 2]. This review is limited to various work geared towards reduction of noise generated in the aircraft wing which is a part of airframe of an aircraft. Airfoil noise emission emanates from the wing section of an aircraft due to the interaction of the airfoil turbulent boundary layer with the sharp leading edge [3] and vortex action on trailing edge. Various techniques have been developed towards the mitigation of noise coming from this source through various approaches such as carrying out some theoretical evaluation, computational and experimental method. Some of the techniques include the introduction of serrations on the leading edge and trailing edge, use of active flow control, flexible wing structure etc. Many of the techniques are bio inspired by studying the silence flight of an owl bird [15, 18]. Many researchers tried to mimic and make a mechanism that can function like the feathers or wings of owl bird. Basically, in the past, two major techniques were employed which can be categorized into two which were the active and passive techniques [10-13]. The active techniques involve the addition of devices such as actuator which by using some energy as input manipulate the flow around them. The passive technique involves changing or altering the