【摘要】 通过分析不同来流边界层厚度与空腔深度比(δ/D)下腔内中心线上的脉动声压级的分布和不同测点的声压频谱特性,讨论了超声速来流边界层厚度对浅腔(长深比分别为12和15)声学特性的影响.试验来流马赫数为1.5,基于每米的雷诺数为2.26×107.结果表明,δ/D减小导致浅腔内的噪声更加强烈,腔前后部的声压级分布更不均匀;除了个别离散频率外,腔内不同测点其余离散频率对应的声压级都有不同程度的增大.δ/D减小引起空腔前部和后部区域几乎整个离散频率范围内的噪声声压级有明显升高;因超声速浅腔流动,腔中部产生的激波的干扰因素的影响,边界层流动特性对浅腔中部区域的声学特性影响较小.更多还原

【Abstract】 An experimental investigation had been constructed to perform effects of boundary-layer thickness on shallow cavity noise characteristics,and sound pressure level(SPL) distributions and sound pressure frequency spectrum(SPFS) characteristics inside shallow cavities with length to depth ratios of 12 and 15 at supersonic speeds were analyzed.The data presented herein was obtained over a Mach number of 1.5 at a Reynolds number of 2.26×107 per meter.The results show that decrease in ratios of the boundary-layer thickness to the cavity depth(δ/D) causes flow oscillation amplification,noise enhancement inside the shallow cavities.Decrease in δ/D leads to obvious increases in SPL in the most frequencies at different positions measurement in the forward and rearward of the shallow cavities.Shock waves in the middle of the shallow cavities which induced by supersonic free-stream flow disturb the flow structure,which makes boundary-layer flow characteristics has few influences on the aeroacoustic characteristics in the middle of the shallow cavities.Generally,decrease in boundary-layer thickness has significant influences on flow oscillations and noise characteristics of shallow cavity at supersonic speeds.更多还原