Supersonic Underexpanded Jet Features Extracted from Modal Analyses of High-Speed Optical Diagnostics

Price, Theron J.; Gragston, Mark; Kreth, Phillip A.

doi:10.2514/1.j059963

Cited by 9 publications

(2 citation statements)

References 70 publications

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“…The experimental techniques in the aeroacoustic field have evolved alongside improvements in the specifications of measurement devices and the development of superior analytic algorithms. For example, schlieren, particle image velocimetry (PIV), and pressure-sensitive paint (PSP) methods can visualize density gradient fields [21][22][23][24], velocity fields [25][26][27][28][29], and surface pressure fields [30], respectively. These experimental techniques are productive and enable us to easily conduct parametric studies.…”

Section: Introductionmentioning

confidence: 99%

Data Assimilation of Ideally Expanded Supersonic Jet Using RANS Simulation for High-Resolution PIV Data

Ozawa,

Nonomura

2024

Aerospace

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Data assimilation using particle image velocimetry (PIV) and Reynolds-averaged Navier–Stokes (RANS) simulation was performed for an ideally expanded supersonic jet flying at a Mach number of 2.0. The present study aims to efficiently reconstruct all the physical quantities in the aeroacoustic fields that match well with a realistic, experimentally obtained flow field. The two-dimensional, two-component PIV measurement was applied to the jet axis plane, and the time-averaged velocity field was obtained using single-pixel ensemble correlation. Two-dimensional axisymmetric RANS simulation using the Menter shear stress transport (SST) model was also performed, and the parameters of the SST model were optimized via data assimilation using the ensemble Kalman filter. The standard deviation of the observation noise σ, which is a parameter of the ensemble Kalman filter, is estimated by the previously proposed method (Nakamura et al., Low-Grid-Resolution-RANS-Based Data Assimilation of Time-Averaged Separated Flow Obtained by LES. Int. J. Comp. Fluid. Dyn., 2022), and its effectiveness was investigated for the first time. This method effectively estimated the magnitude of σ at each generation without tuning the hyperparameters. The assimilated flow fields exhibited similar flow structures observed in PIV such as the potential core length or shear layer. Therefore, the present framework can be used to estimate time-averaged full flow fields that match well with experimentally observed flow fields, and has the potential to construct a database for the Navier-Stokes-based stability analysis that requires a full flow field.

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Section: Introductionmentioning

confidence: 99%

Data Assimilation of Ideally Expanded Supersonic Jet Using RANS Simulation for High-Resolution PIV Data

Ozawa,

Nonomura

2024

Aerospace

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“…Therefore, the improvement of spatial resolution for the instantaneous fields is not straightforward and is left for future work. Additionally, time-resolved PIV for a high-speed flow requires an expensive high-repetition burst laser system (Price et al, 2021;Beresh et al, 2015). Owing to the insufficient camera performance or the expensive burst laser system described above, the spatiotemporal superresolution measurement, which is a reconstruction of the time-resolved data from the non-time-resolved data acquired with the existing experimental devices, can be a powerful experimental technique for analyzing high-speed flow phenomena.…”

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confidence: 99%

Spatiotemporal Superresolution Measurement based on POD and Sparse Regression applied to a Supersonic Jet measured by PIV and Near-field Microphone

Ozawa,

Nagata,

Nonomura

2022

Preprint

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The present study proposed the framework of the spatiotemporal superresolution measurement based on the and sparse regression with dimensionality reduction using the proper orthogonal decomposition (POD). The non-time-resolved particle image velocimetry (PIV) and the time-resolved near-field acoustic measurements using microphones were simultaneously performed for a Mach 1.35 supersonic jet. POD is applied to PIV and microphone data matrices and the sparse linear regression model of the reduced-order data is calculated using the least absolute shrinkage and selection operator regression. The effects of the hyperparameters of the superresolution measurement were quantitatively evaluated through randomized cross-validation. The superresolved velocity field indicated the smooth convection of the velocity fluctuations associated with the screech tone, while the convection of the large-scale structures at the downstream side was not observed. The proposed framework can reconstruct the unsteady fluctuation with multiple frequency phenomena, although the reconstruction is limited to the phenomena that is associated with the microphone output.

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Detection method for shock-waves in viscous flows

et al. 2021

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Supersonic Underexpanded Jet Features Extracted from Modal Analyses of High-Speed Optical Diagnostics

Cited by 9 publications

References 70 publications

Data Assimilation of Ideally Expanded Supersonic Jet Using RANS Simulation for High-Resolution PIV Data

Data Assimilation of Ideally Expanded Supersonic Jet Using RANS Simulation for High-Resolution PIV Data

Spatiotemporal Superresolution Measurement based on POD and Sparse Regression applied to a Supersonic Jet measured by PIV and Near-field Microphone

Detection method for shock-waves in viscous flows

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