Research On Optimization of Two-Dimensional Supersonic Jet Noise Reduction.

二维超音速射流降噪优化研究。

• 批准号: 05555259
• 负责人: KAJI Shojiro
• 金额: $ 6.59万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Developmental Scientific Research (B)
• 财政年份: 1993
• 资助国家: 日本
• 起止时间: 1993 至 1995
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-05555259/
• 关键词: supersonic jet noise; jet screech; porous plug nozzle; mixer nozzle; ejector nozzle; 超音速ジェット; ジェットノイズ; スクリーチ; ショックセル; パルスシュリーレン法; 音響タブ; ジェットノズル

For the purpose of reducing supersonic jet noise, application of porous plug nozzle as well as ejector nozzle was investigated. In the case where an airfoil shaped porous plug was inserted into two dimensional rectangular nozzle, its effect on screech and shock associate noise was studied. When the porous plug was placed a little far downstream from the jet nozzle, sound of the edge-tone type mechanism appeared. When the leading edge of the porous plug approached the jet nozzle exit, edge tone disappeared but screech appeared. Further, when the leading edge of the porous plug was inserted into the jet nozzle, screech also vanished. Such tendency was considered to be ascribable to the highly turbulent flow around the porous plug though holes which was observed by flow visualization.The method to reduce noise by rapidly reducing the velocity of high speed jet by use of mixer-ejector nozzle was studied. Measurement of fluctuating pressures on ejector wall showed that in the upstream part of the mixer-ejector nozzle the lower frequency component was dominant while the higher frequency component became dominant in the downstream part, and further, the level of both components increased as we went downstream.The flow field showing the mixing process in the mixer-ejector nozzle was simulated by the computational fluid dynamics. It was revealed that in the mixing process of core and secondary flows, the supersonic core flow repeats compression and expansion several times, then the rolling up of a large scale streamwise vortex starts which is strengthened as the flow proceeds downstream.

为了降低超音速射流噪声，研究了多孔塞式喷嘴和喷射器喷嘴的应用。在二维矩形喷管中插入翼型多孔塞，研究了其对尖叫噪声和激波噪声的影响。当多孔塞放置在离喷嘴较远的下游位置时，出现了边缘音型机构的声音。当多孔塞的前缘靠近喷嘴出口时，边缘音消失，但出现尖啸。此外，当多孔塞的前缘插入喷嘴时，尖锐声也消失了。这种趋势被认为是由流动显示观察到的多孔塞孔周围的高湍流引起的。研究了利用混合喷射器快速降低高速射流速度以降低噪声的方法。对喷射器壁面脉动压力的测量表明，在混合式喷射器的上游以低频分量为主，下游以高频分量为主，并且随着下游的移动，两种分量的水平都在增加。采用计算流体力学方法对混合喷射器内的混合过程进行了流场模拟。结果表明，在芯流与二次流的混合过程中，超声速芯流多次重复压缩和膨胀，然后开始大规模的向流涡旋卷起，并随着流动的下游而加强。