The presence of a cavity changes the mean and fluctuating pressure distributions. Similarities are observed between a cylindrical cavity and a rectangular cavity for a compressible flow.The type of cavity flow field d...The presence of a cavity changes the mean and fluctuating pressure distributions. Similarities are observed between a cylindrical cavity and a rectangular cavity for a compressible flow.The type of cavity flow field depends on the diameter-to-depth ratio and the length-to-depth ratio.The feedback loop is responsible for the generation of discrete acoustic tones. In this study, the selfsustained oscillation for a compressible cylindrical cavity flow was investigated experimentally. For open-type cavities, the power spectra show that the strength of resonance depends on the diameterto-depth ratio（4.43–43.0） and the incoming boundary layer thickness-to-depth ratio（0.72–7.0）. The effective streamwise length is used as the characteristic length to estimate the Strouhal number. At higher modes, there is a large deviation from Rossiter＇s formula for rectangular cavities. The gradient-based searching method was used to evaluate the values of the empirical parameters. Less phase lag and a lower convection velocity are observed.展开更多
Presence of a cavity changes the mean and fluctuating pressure distributions inside and near the cavity.For cylindrical cavity flow,the diameter-to-depth ratio is the dominant factor.In this study,flow is naturally de...Presence of a cavity changes the mean and fluctuating pressure distributions inside and near the cavity.For cylindrical cavity flow,the diameter-to-depth ratio is the dominant factor.In this study,flow is naturally developed along a flat plate with two different lengths,resulting in different incoming boundary layer thicknesses ahead of the cavity.The effect of Reynolds number based on incoming boundary layer thickness on characteristics of mean and fluctuating pressure distributions is addressed.Pressure sensitive paint was also used to visualize the mean surface pressure patterns.The effect of Reynolds number on the classification of compressible cylindrical cavity flow and self-sustained oscillating frequency is not significant.An increase in Reynolds number results in a reduction in the value of differential pressure or momentum flux near the rear edge.展开更多
基金support of the Ministry of Science and Technology (No. MOST 103-2923-E-006MY3)
文摘The presence of a cavity changes the mean and fluctuating pressure distributions. Similarities are observed between a cylindrical cavity and a rectangular cavity for a compressible flow.The type of cavity flow field depends on the diameter-to-depth ratio and the length-to-depth ratio.The feedback loop is responsible for the generation of discrete acoustic tones. In this study, the selfsustained oscillation for a compressible cylindrical cavity flow was investigated experimentally. For open-type cavities, the power spectra show that the strength of resonance depends on the diameterto-depth ratio（4.43–43.0） and the incoming boundary layer thickness-to-depth ratio（0.72–7.0）. The effective streamwise length is used as the characteristic length to estimate the Strouhal number. At higher modes, there is a large deviation from Rossiter＇s formula for rectangular cavities. The gradient-based searching method was used to evaluate the values of the empirical parameters. Less phase lag and a lower convection velocity are observed.
基金financial support from the Ministry of Science and Technology,Taiwan,China(MOST 1032923-E-006-006-MY3).
文摘Presence of a cavity changes the mean and fluctuating pressure distributions inside and near the cavity.For cylindrical cavity flow,the diameter-to-depth ratio is the dominant factor.In this study,flow is naturally developed along a flat plate with two different lengths,resulting in different incoming boundary layer thicknesses ahead of the cavity.The effect of Reynolds number based on incoming boundary layer thickness on characteristics of mean and fluctuating pressure distributions is addressed.Pressure sensitive paint was also used to visualize the mean surface pressure patterns.The effect of Reynolds number on the classification of compressible cylindrical cavity flow and self-sustained oscillating frequency is not significant.An increase in Reynolds number results in a reduction in the value of differential pressure or momentum flux near the rear edge.
