Methodology to image the panel surface pressure power spectra in weakly coupled fluid/structure interactions

Varigonda, Santosh Vaibhav; Narayanaswamy, Venkateswaran

doi:10.1007/s00348-021-03314-4

Cited by 8 publications

(1 citation statement)

References 38 publications

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“…The normalized images are then calibrated using the procedures described in the following sections. Finally, the calibrated pressure fields are binned pixels following Varigonda & Narayanaswamy (2021) to provide the best signal-to-noise ratio of the pressure fields without impacting the dynamic content of the pressure field. The resulting spatial resolution of the pressure fields is 0.78 mm per binned pixel.…”

Section: Experimental Set-upmentioning

confidence: 99%

Investigations of shock–boundary layer interaction dynamics using high-bandwidth pressure field imaging

2023

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The large-scale pulsations of shock-induced separation with length scale that significantly exceeds the incoming boundary layer thickness are investigated. The shock–boundary layer interaction (SBLI) unit is generated by an inward-turning axisymmetric compression ramp at an inflow Mach number of 2.5. A substantial region surrounding the centre azimuth exhibited mean and dynamic flow features that are consistent with two-dimensional separation. Two-dimensional highly resolved maps of surface pressure field are obtained using fast-response pressure-sensitive paint fluorescence imaging at 40 kHz repetition rate. The measurement domain covered significant regions of the incoming boundary layer through the relaxing boundary layer downstream of the reattachment as well as over 25 boundary layer thicknesses in the azimuthal direction. These measurements provide new insights into the spanwise coupling of the SBLI unit in addition to its inherent dynamics. The power spectral density (PSD) of the centreline pressure exhibits very good agreement with theoretical models and complementary measurements using fast-response pressure transducers, which served to validate the pressure field measurements. Detailed examination of the PSD reveals strong agreement with the literature, which includes the peak Strouhal number of the separation and reattachment shock motions as well as the downward frequency shift along the separation bubble. Furthermore, the pressure fluctuation maps reveal streamwise-elongated structures just downstream of the ramp leading edge that persist well downstream of the reattachment. A time sequence of conditional average pressure fluctuation maps is constructed surrounding isolated pressure excursions in the intermittent region. This sequence, along with two-point cross correlation analysis, provides critical information about the flow processes that drive the separation bubble pulsations in the SBLI units with large separation scales. Overall, the imbalance in the mass within the separation bubble appears to be the critical mechanism that drives the separation bubble pulsations. Furthermore, the pressure perturbations originating at azimuthally offset locations are also observed to influence the separation bubble dynamics.

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Section: Experimental Set-upmentioning

confidence: 99%

Investigations of shock–boundary layer interaction dynamics using high-bandwidth pressure field imaging

2023

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Time-series image denoising of pressure-sensitive paint data by projected multivariate singular spectrum analysis

2022

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Time-series data, such as unsteady pressure-sensitive paint (PSP) measurement data, may contain a significant amount of random noise. Thus, in this study, we investigated a noise-reduction method that combines multivariate singular spectrum analysis (MSSA) with low-dimensional data representation. MSSA is a state-space reconstruction technique that utilizes time-delay embedding, and the low-dimensional representation is achieved by projecting data onto the singular value decomposition (SVD) basis. The noise-reduction performance of the proposed method for unsteady PSP data, i.e., the projected MSSA, is compared with that of the truncated SVD method, one of the most employed noise-reduction methods. The result shows that the projected MSSA exhibits better performance in reducing random noise than the truncated SVD method. Additionally, in contrast to that of the truncated SVD method, the performance of the projected MSSA is less sensitive to the truncation rank. The projected MSSA achieves denoising effectively by extracting smooth trajectories in a state space from noisy input data. Expectedly, the projected MSSA will be effective for reducing random noise in not only PSP measurement data, but also various high-dimensional time-series data. Graphic abstract

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Fluid–structure interaction with the spectral method: application to a cylindrical tube subjected to transverse flow

Drissi

Mansouri

Mesmoudi

2022

Int. J. Dynam. Control

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Methodology to image the panel surface pressure power spectra in weakly coupled fluid/structure interactions

Cited by 8 publications

References 38 publications

Investigations of shock–boundary layer interaction dynamics using high-bandwidth pressure field imaging

Investigations of shock–boundary layer interaction dynamics using high-bandwidth pressure field imaging

Time-series image denoising of pressure-sensitive paint data by projected multivariate singular spectrum analysis

Fluid–structure interaction with the spectral method: application to a cylindrical tube subjected to transverse flow

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