Experimental study of the effects of confinement on self-sustained oscillations and noise radiation in three-dimensional open cavities
-
摘要: 实验研究了侧壁约束效应对三维方腔流动结构和噪声辐射特性的影响，固定方腔长深比为2∶1，使用麦克风阵列测量了方腔宽长比从0.1变化至0.5过程中流致噪声在不同指向性下的强度变化规律，并使用脉动压力传感器测量了不同宽长比方腔内部壁面压力分布，同时采用TR-PIV（Time-Resolved Particle Image Velocimetry）测量了方腔内流动结构的发展。实验结果表明：对于宽长比为0.5的方腔，当来流马赫数大于0.03时，方腔流动开始出现振荡并向上游辐射噪声；当来流马赫数增大至0.20时，方腔流动发展为对应Rossiter三阶模态的自持振荡，并辐射出尖频噪声。减小方腔宽度，当宽长比小于0.3时，方腔流动的自持振荡和尖频噪声被大幅度抑制甚至消除，来流马赫数为0.20和0.25时，方腔上游总声压级能够降低3 dB以上。通过对比壁面压力分布和PIV流场测量结果，发现减小方腔宽长比时，方腔内主回流涡向上游移动，涡强度降低，使得方腔的流动反馈不足以形成自持振荡，从而降低了辐射噪声。Abstract: Flow past an open cavity has been studied extensively, while less attention has been paid to the effects of confinement due to side walls, which produces rich flow dynamics and noise characteristics. In this study, the effects of confinement on flow structures and noise radiation in three-dimensional rectangular cavities are investigated experimentally. The length and depth are fixed, and five ratios of width/length （W/L=0.1–0.5） are considered. The measurements are performed in an acoustic wind tunnel. The pressure oscillations are onset after the wind speed is greater than Ma 0.03. Once the wind speed is greater than or equal to Ma 0.20, the flow and noise radiation are dominated by the self-sustained oscillations corresponding to the third Rossiter’s mode. Furthermore, the present experiments show that the local pressure oscillations and noise radiation of this frequency can be weakened or even eliminated when W/L is equal to or less than 0.3 for the wind speeds of Ma 0.20 and Ma 0.25. The upstream OASPLs in the far field can be reduced by more than 3 dB when W/L decreases from 0.4 to 0.3 at Ma 0.20. By analyzing the surface pressure and TR-PIV（Time-Resolved Particle Image Velocimetry） results, it is found that the suppression of the tonal noise is closely related with the changes of the primary recirculation and some secondary vortical structures by decreasing W/L. In particular, the intensity of the primary recirculation is greatly weakened with strong confinement effects, and the feedback process is not strong enough to produce self-sustained oscillations.
-
Key words:
- cavity flow /
- confinement effect /
- aeroacoustic feedback /
- oscillation suppression /
- vortex motion
-
图 3 水平面和垂直平面的麦克风阵列布置示意图
Figure 3. The arrangement of microphone arrays in horizontal and vertical directions
图 4 方腔内壁面脉动压力传感器布置示意图
Figure 4. The arrangement of high frequency dynamic pressure sensors on the cavity walls
图 6 不同风速下的方腔远场噪声频谱特性（W/L=0.5）
Figure 6. PSD distributions for different wind speeds at W/L=0.5
图 8 宽长比0.3与0.4的方腔噪声总声压级对比（Ma=0.20）
Figure 8. OASPL comparison between cases with W/L=0.3 and W/L=0.4 at a wind speed of Ma 0.20
图 9 方腔内壁面脉动压力频谱与远场噪声频谱的对比（Ma=0.20，W/L=0.5）
Figure 9. PSD distributions based on surface pressure fluctuations at local pressure sensors 1 and 2 and at far-field microphone 12 with a wind speed of Ma 0.20 and W/L=0.5
图 10 宽长比0.1与0.5的方腔壁面时均压力系数对比（Ma=0.20）
Figure 10. Comparison of mean pressure coefficients between the cases with W/L=0.5 and W/L=0.1 at Ma 0.20
图 11 一个振荡周期内方腔瞬时流场变化（Ma=0.20，W/L=0.5）
Figure 11. Six snapshots of flow pattern in a period T0 in the central plane at a wind speed of Ma 0.20 and W/L=0.5. The streamlines are shown, while the background denotes the field of spanwise vorticity
图 12 方腔中心平面和近壁面时均流场分布对比（Ma=0.20，W/L=0.5）
Figure 12. Mean flow pattern comparison between central plane and near wall plane at the wind speed of Ma 0.20 (W/L=0.5)
图 13 不同宽长比方腔中心平面时均流场对比（Ma=0.20）
Figure 13. The comparison of mean flow patterns in the central plane for different W/L at the wind speed of Ma 0.20
-
[1] HUBBARD H H. Aeroacoustics of flight vehicles: theory and practice[R]. NASA-RP-1258, 1991. [2] DOBRZYNSKI W. Almost 40 years of airframe noise research: what did we achieve?[J]. Journal of Aircraft,2010,47(2):353-367. doi: 10.2514/1.44457 [3] HELLER H H,DOBRZYNSKI W M. Sound radiation from aircraft wheel-well/landing-gear configurations[J]. Journal of Aircraft,1977,14(8):768-774. doi: 10.2514/3.58851 [4] ZIADA S,NG H,BLAKE C E. Flow excited resonance of a confined shallow cavity in low Mach number flow and its control[J]. Journal of Fluids and Structures,2003,18(1):79-92. doi: 10.1016/S0889-9746(03)00083-5 [5] ROSHKO A. Some measurements of flow in a rectangular cutout[R]. NACA-TN-3488, 1955. [6] TRACY M B, PLENTOVICH E B. Cavity unsteady-pressure measurements at subsonic and transonic speeds[R]. NASA-97-tp3669, 1997. [7] BASLEY J,PASTUR L R,DELPRAT N,et al. Space-time aspects of a three-dimensional multi-modulated open cavity flow[J]. Physics of Fluids,2013,25(6):064105. doi: 10.1063/1.4811692 [8] TAM C K W,PASTOUCHENKO N N,JONES M G,et al. Experimental validation of numerical simulations for an acoustic liner in grazing flow: Self-noise and added drag[J]. Journal of Sound and Vibration,2014,333(13):2831-2854. doi: 10.1016/j.jsv.2014.02.019 [9] ROSSITER J E. Wind tunnel experiments on the flow over rectangular cavities at subsonic and transonic speeds[EB/OL]. （1964）[2021-05-20]. https://reports.aerade.cranfield.ac.uk/handle/1826.2/4020. [10] GHARIB M,ROSHKO A. The effect of flow oscillations on cavity drag[J]. Journal of Fluid Mechanics,1987,177:501-530. doi: 10.1017/s002211208700106x [11] COLONIUS T, BASU A J, ROWLEY C W. Numerical investigation of the flow past a cavity[C]//Proc of the 5th AIAA/CEAS Aeroacoustics Conference and Exhibit. 1999. doi: 10.2514/6.1999-1912 [12] SHIEH C M, MORRIS P J. Comparison of two- and three-dimensional turbulent cavity flows[C]//Proc of the 39th Aerospace Sciences Meeting and Exhibit. 2001. doi: 10.2514/6.2001-511 [13] MARTIN R,SORIA M,LEHMKUHL O,et al. Noise radiated by an open cavity at low Mach number: Effect of the cavity oscillation mode[J]. International Journal of Aeroacoustics,2019,18(6-7):647-668. doi: 10.1177/1475472x19871534 [14] ZHANG C,WAN Z H,SUN D J. Mode transition and oscillation suppression in supersonic cavity flow[J]. Applied Mathematics and Mechanics,2016,37(7):941-956. doi: 10.1007/s10483-016-2095-9 [15] BLOCK P J W. Noise response of cavities of varying dimensions at subsonic speeds[R]. NASA-TN-D-8351, 1976. [16] AHUJA K K, MENDOZA J. Effects of cavity dimensions, boundary layer, and temperature on cavity noise with emphasis on benchmark data to validate computational aeroacoustic codes[R]. NASA-CR-4653, 1995. [17] PICELLA F,LOISEAU J-C,LUSSEYRAN F,et al. Successive bifurcations in a fully three-dimensional open cavity flow[J]. Journal of Fluid Mechanics,2018,844:855-877. doi: 10.1017/jfm.2018.169 [18] SUN Y Y,LIU Q,CATTAFESTA L N Ⅲ,et al. Effects of sidewalls and leading-edge blowing on flows over long rectangular cavities[J]. AIAA Journal,2018,57(1):106-119. doi: 10.2514/1.J057413 [19] WELCH P. The use of fast Fourier transform for the estimation of power spectra: a method based on time averag-ing over short, modified periodograms[J]. IEEE Transactions on Audio and Electroacoustics,1967,15(2):70-73. doi: 10.1109/TAU.1967.1161901 [20] HARRIS F J. On the use of windows for harmonic analysis with the discrete Fourier transform[J]. Proceedings of the IEEE,1978,66(1):51-83. doi: 10.1109/PROC.1978.10837 [21] ROCKWELL D,NAUDASCHER E. Review—Self-sustaining oscillations of flow past cavities[J]. Journal of Fluids Engineering,1978,100(2):152-165. doi: 10.1115/1.3448624 [22] UNALMIS O H,CLEMENS N T,DOLLING D S. Cavity oscillation mechanisms in high-speed flows[J]. AIAA Journal,2004,42(10):2035-2041. doi: 10.2514/1.1000 [23] CROOK S D,LAU T C W,KELSO R M. Three-dimensional flow within shallow, narrow cavities[J]. Jour-nal of Fluid Mechanics,2013,735:587-612. doi: 10.1017/jfm.2013.519 -
下载:
点击查看大图
计量
- 文章访问数: 612
- HTML全文浏览量: 236
- PDF下载量: 61
- 被引次数: 0
