方案摘要
方案下载应用领域 | 其他 |
检测样本 | 其他 |
检测项目 | |
参考标准 | 暂无 |
One of the major environmental problems facing the aviation industry is that of aircraft noise. The work presented in this paper, done as part of the EU’s OPENAIR Project, looks at reducing spoiler noise whilst maintaining aerodynamic performance, through means of large-scale fractal porosity. It is hypothesised that the highly turbulent flow generated by fractal grids from the way the multiple-length-scales are organised in space, would reduce the impact of the re-circulation region and with it, the low frequency noise it generates. In its place, a higher frequency noise is introduced which is more susceptible to atmospheric attenuation and is less offensive to the human ear. A total of nine laboratory scaled spoilers were looked at, seven of which had a fractal design, one with a regular grid design and one solid for reference. The spoilers were inclined at an angle of 30. Force, acoustic and flow visualisation experiments on a flat plate were carried out and it was found that the present fractal spoilers reduce the low frequency noise by 2.5dB. Results show that it is possible to improve the acoustic performance by modifying a number of parameters defining the fractal spoiler, some of them very sensitively. From these experiments, two fractal spoilers were chosen for a detailed aero-acoustic study on a three-element wing system, where it was found that the fractal spoilers had a reduction of up to 4dB in the sound pressure level while maintaining similar aerodynamic performances as conventional solid spoilers on the measured wing system.
在一个双稳湍流涡旋火焰中,对间歇性动态的时间-频率定位
Particle-laden Taylor-Couette流:高阶转变和径向局部波浪涡旋的证据
7根杆束的流体-结构相互作用:用实验数据对比数值模拟
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