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首页> 外文会议>AHS 59th Annual Forum Proceedings Vol.1 May 6-8, 2003 Phoenix, Arizona >Helicopter Acoustic Characterization by Simulation: Comparison with Flight Test Results and Predicted Impact of New Design Solutions
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Helicopter Acoustic Characterization by Simulation: Comparison with Flight Test Results and Predicted Impact of New Design Solutions

机译：通过仿真对直升机进行声学表征：与飞行测试结果进行比较以及新设计解决方案的预期影响

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The proposed paper describes the application of the "AGUSTA Operational Aeroacoustic Simulator" to a real flying helicopter. Differently from the development phase, in which wind tunnel data were mainly exploited for validation activity, the simulation tool has been tested here through direct comparisons with flight test results coming from an acoustic campaign of a light turbine engined helicopter. The aircraft was flown over a ground mounted linear microphone array and covered a wide range of flight operations; acoustic measurements on the ground were synchronized to accurate flight trajectory data recorded by means of a DGPS system. Selected test results are presented and compared to numerical simulations in terms of noise footprints emitted in stabilized flight conditions. From the simulation technique point of view, particular emphasis has been given to the aerodynamic calculation accuracy: a tool has been exploited that is supposed to offer a realistic simulation of rotor-wake interaction, by coupling a vortex lattice code for wake system prediction with an Euler code for flow field calculation around blades. Acoustic behaviour of both rotors has been evaluated through a Linear Fofwcs Williams-Hawkings formulation and also fuselage scattering effects have been included in the calculations. Good correlation has been achieved with experimental results, especially considering the complications induced by the heavy directivity characteristics of radiated noise as well as the repeatability problems mainly due to the high variability of meteorological parameters, together with the difficulty in maintaining perfectly stabilized flight conditions during the tests. These are on the other hand the main reasons that make the flying helicopter acoustic characterization through mere prediction an extremely challenging task: most of the available computational techniques are indeed limited at interpolating experimentally acquired database for determination of the far field sound radiation coming from the main and tail rotors throughout the flight regime, rather than directly simulating noise emission at sound sources. The final part of the paper deals with a further practical application of the prediction methodology, aimed at assessing the acoustic impact of a new experimental tail rotor which has been developed as the result of a research activity, having the acoustic performance improvement as one of the main design constraints. The experimental tests to be conducted on the new configuration tail rotor are expected to provide a useful database for validation activity of blind calculations.
机译：拟议论文描述了“ AGUSTA航空声学模拟器”在实际飞行直升机中的应用。与开发阶段不同，在开发阶段主要利用风洞数据进行验证活动，此处已通过与来自轻型涡轮发动机直升机的声学战役的飞行测试结果进行直接比较，对模拟工具进行了测试。飞机在地面安装的线性麦克风阵列上空飞行，涵盖了广泛的飞行操作；地面上的声学测量结果与DGPS系统记录的准确的飞行轨迹数据同步。呈现选定的测试结果并将其与数值模拟进行比较，以证明在稳定飞行条件下发出的噪声足迹。从仿真技术的角度来看，已经特别强调了空气动力学计算的准确性：已经开发了一种工具，该工具通过将用于尾流系统预测的涡流晶格代码与一个尾流耦合，可以提供对转子-尾流相互作用的真实模拟。欧拉代码，用于叶片周围的流场计算。通过线性Fofwcs Williams-Hawkings公式评估了两个转子的声学特性，并且在计算中还包括了机身散射效应。与实验结果已经取得了良好的相关性，特别是考虑到辐射噪声的重指向性特性引起的复杂性以及主要由于气象参数的高可变性以及在飞行过程中难以保持完美稳定的飞行条件而引起的重复性问题。测试。另一方面，这是使通过简单的预测对飞行直升机的声学特性进行表征成为一项极具挑战性的任务的主要原因：实际上，大多数可用的计算技术实际上仅限于内插通过实验获得的数据库来确定来自主辐射源的远场声辐射。和整个飞行过程中的尾旋翼，而不是直接模拟声源的噪声发射。本文的最后一部分讨论了预测方法的进一步实际应用，旨在评估作为研究活动的结果而开发的新型实验性尾桨的声学影响，该声学尾声是其中一项改进。主要设计约束。预期将在新配置的尾桨上进行的实验测试将为盲目计算的验证活动提供有用的数据库。

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