不同马赫数下长深比对空腔声学特性的影响  

INVESTIGATIONS ON AEROACOUSTIC CHARACTERISTICS INSIDE CAVITIES INFLUENCED BY LENGTH-DEPTH RATIOS AT DIFFERENT MACH NUMBERS

作　　者：杨党国[1] 李建强[1] 蒋卫民[1] 罗新福[1] 吴继飞[1] 

机构地区：[1]中国空气动力研究与发展中心,四川绵阳621000

出　　处：《工程力学》2011年第12期221-225,237,共6页Engineering Mechanics

基　　金：国家"973"计划课题项目(2009CB723802);"863"计划项目(2007AA04Z129)

摘　　要：通过对比亚声速(Ma=0.6)和超声速(Ma=1.5)时不同长深比空腔内的声压级分布和声压频谱特性,探讨了长深比(L/D)对空腔声学特性的影响。结果表明:空腔长深比从7、8增大至9、再到12、15时,空腔从开式流动逐渐转变为过渡式或闭式流动;腔内声压级分布和声压频谱特性发生改变。当L/D较小时(如7和8),空腔内的声波反馈回路受空腔上方剪切层或膨胀波与激波等的影响较小,腔内存在较多的声压峰值激振频率,说明腔内流动自激振荡较剧烈;当L/D增大至12或15时,剪切层或激波等阻碍了腔内声波反馈回路,腔内流动自激振荡较弱或消失,腔内几乎未出现声压峰值激振频率。可见,L/D增大,腔内声压峰值激振频率个数减少,流动自激振荡较弱,且相同激振频率对应的声压峰值较小。Effects of cavity length-depth ratios（L/D） on aeroacoustic characteristics of cavities were discussed at Mach numbers of 0.6 and 1.5 by analyzing sound pressure level（SPL） distributions and sound pressure frequency spectrum（SPFS） inside the cavities.The results indicate that there is a transformation that the cavity flow type changes from open to transitional and closed cavity flow when L/D is increased from 7,8 to 9,12 and 15,which also leads to changes in SPL distributions and SPFS characteristics inside the cavities.When L/D is 7 and 8,some flow oscillation frequencies exist because the shear-layer,expansion or shock waves have insignificant influences on sound feedback mechanism,which indicate self-sustained oscillations appear inside the cavities.However,there are few oscillation frequencies and flow self-sustained oscillations inside the cavities with length-depth ratios of 12 and 15 because the shear-layer,expansion or shock waves weaken the self-sustained oscillation energy and disturb the sound feedback mechanism.Generally,increase in L/D leads to reduction in flow oscillation frequencies and decrease in SPL in the oscillation frequencies.

关 键 词：气动声学 空腔 长深比 声学特性 声压级 声压频谱特性 

分 类 号：O424[理学—声学]