Kent L Gee, Matthew A. Christian, Hunter J. Pratt, Michèle L. Eggleston
{"title":"Recent findings regarding noise from tactical jet engines","authors":"Kent L Gee, Matthew A. Christian, Hunter J. Pratt, Michèle L. Eggleston","doi":"10.1121/10.0023676","DOIUrl":null,"url":null,"abstract":"This paper reviews the outcomes of several recent investigations into full-scale supersonic jet noise. First, concordance has been shown between a T-7A-installed GE F404 engine’s sound power and classical jet noise theory in both the subsonic and supersonic regimes [M. A. Christian et al., JASA Express Lett. 3, 073601 (2023)]. The results indicate approximate agreement between the “eighth-power” law for subsonic engine conditions and the “third-power” law for supersonic engine conditions, with a radiation efficiency of ∼0.5–0.6% at afterburner. However, a sudden jump in radiation efficiency in the jet’s transonic region is not presently explained. Second, normalized far field-derived sound power spectra for the F404 do not agree well with a curve found in NASA SP-8072 (Eldred, 1971), likely indicating differences between the importance of different Strouhal number regimes in military jet and rocket noise and, possibly, different radiation phenomena. Third, the maximum directivity angle for overall level appears to be primarily driven by the convective Mach number associated with Kelvin–Helmholtz instability waves (M. A. Christian et al., AIAA Paper 2023-3351). Together, these recent findings represent improved understanding of full-scale tactical jet noise phenomena. [Work supported by ONR.]","PeriodicalId":256727,"journal":{"name":"The Journal of the Acoustical Society of America","volume":"10 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"The Journal of the Acoustical Society of America","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1121/10.0023676","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
This paper reviews the outcomes of several recent investigations into full-scale supersonic jet noise. First, concordance has been shown between a T-7A-installed GE F404 engine’s sound power and classical jet noise theory in both the subsonic and supersonic regimes [M. A. Christian et al., JASA Express Lett. 3, 073601 (2023)]. The results indicate approximate agreement between the “eighth-power” law for subsonic engine conditions and the “third-power” law for supersonic engine conditions, with a radiation efficiency of ∼0.5–0.6% at afterburner. However, a sudden jump in radiation efficiency in the jet’s transonic region is not presently explained. Second, normalized far field-derived sound power spectra for the F404 do not agree well with a curve found in NASA SP-8072 (Eldred, 1971), likely indicating differences between the importance of different Strouhal number regimes in military jet and rocket noise and, possibly, different radiation phenomena. Third, the maximum directivity angle for overall level appears to be primarily driven by the convective Mach number associated with Kelvin–Helmholtz instability waves (M. A. Christian et al., AIAA Paper 2023-3351). Together, these recent findings represent improved understanding of full-scale tactical jet noise phenomena. [Work supported by ONR.]
本文回顾了最近对全尺寸超音速喷气机噪声的几项研究成果。首先,T-7A 安装的通用电气 F404 发动机在亚音速和超音速状态下的声功率与经典喷气噪声理论之间的一致性已经得到证明[M. A. Christian 等人,JASA Express Lett.3,073601 (2023)]。结果表明,亚音速发动机条件下的 "八级功率 "定律与超音速发动机条件下的 "三级功率 "定律近似一致,后燃时的辐射效率为 0.5-0.6%。然而,喷气机跨音速区域辐射效率的突然跃升目前还无法解释。其次,F404 的归一化远场声功率谱与 NASA SP-8072 中的曲线(Eldred,1971 年)不太一致,这可能表明军用喷气机和火箭噪声中不同斯特劳哈尔数机制的重要性不同,也可能表明辐射现象不同。第三,总体水平的最大指向角似乎主要由与开尔文-赫尔姆霍兹不稳定波相关的对流马赫数驱动(M. A. Christian 等人,AIAA Paper 2023-3351)。总之,这些最新发现表明人们对全尺寸战术喷气机噪声现象的理解有了提高。[工作得到国家航空研究局的支持]。