Understanding the fluctuating flow around two-wheel landing gear systems and innovative solutions for noise mitigation

自商业航空诞生以来，噪音污染一直是飞机的负面副产品。几 调查显示，长期接触飞机噪音与各种健康状况之间存在直接联系。 问题由于公众对这个问题的强烈反应，噪音政策变得越来越周期性。 严格的多年来，由于这种转变，今天，噪音最大的飞机从过去（那些设计之前， 1978年，不再经营商业航线。飞机的逐步淘汰， 日益严格的噪声政策意味着飞机的保留价值可能会大大减少， 如果在逐步停止运行之前没有太多的使用余地，则在其使用寿命的某个时间点。在 此外，根据飞机的噪音排放，飞机每次着陆往往要收费， 对于航空公司运营商来说，具有大量航班的运营可能是一个很大的成本。由于这些原因，航空公司 更倾向于购买更安静的飞机。这使得所有的大型飞机制造商都陷入了 设计最安静的飞机。到目前为止，飞机制造商在降噪方面取得了成功， 主要是通过发动机技术的改进，今天达到的状态是这样的， 在飞机接近着陆时，起落架产生的噪音几乎等于发动机产生的噪音。 起落架噪声主要来源于起落架周围产生的非定常流场结构， 它们与飞机部件之间复杂的相互作用。在这一点上，起落架的基本机构 噪声的产生仍然没有得到很好的理解，因此很难制定有效的策略， 减轻他们的负担。拟议的研究计划将确定噪音的可能原因和来源 通过发展对波动、相干流的全面了解， 起落架的各种几何细节。通过知识的进步， 在这一领域，人们期望能够开发出新的技术或方法来实现起落架的减少 与现有设计相比，该项目是与庞巴迪合作提出的。

Since the dawn of commercial aviation, noise pollution has been a negative by-product of aircraft. Several surveys have shown direct associations between extended exposure to aircraft noise and various health problems. As a result of strong public response to this issue, noise policies became periodically more and more stringent over the years, and owing to this shift, today, the noisiest aircraft from past (those designed before 1978) can no longer operate on commercial routes. The phasing out of aircraft as a consequence of the increasingly stringent noise policies implies that the retained value of an aircraft may dramatically reduce at a certain point in its life if it does not have much margin for use before being phased out of operation. In addition, based on their noise emission, aircraft are often charged fees per landing, which over a typical year of operation with numerous flights can be a significant cost to airline operators. For these reasons, airlines are more inclined towards purchasing quieter aircraft. This puts all the large aircraft manufacturers into a competition to design the quietest aircraft. So far, the success of aircraft manufacturers in noise reduction has been mostly through the improvements in engine technology and the state achieved today is such that, during approach to landing, the noise generated by landing gears is almost equal to that generated by the engines. Landing gear noise mainly results from the unsteady flow structures that are generated around landing gear and their complex interactions with the aircraft components. At this point, the basic mechanisms of landing gear noise generation are still not well understood and it is therefore difficult to develop efficient strategies to mitigate against them. The proposed research program will identify the possible causes and sources of noise generation for landing gears by developing a comprehensive understanding of the fluctuating, coherent flow structures attributable to various geometric details of landing gear. Through the advancement of knowledge in this area, it is expected that new techniques or methods will be developed to realize reductions in landing-gear noise compared to the present designs. This project is proposed in collaboration with Bombardier.