Integration of non-time-resolved PIV and time-resolved velocity point sensors for dynamic estimation of time-resolved velocity fields

Tu, Jonathan H.; Rowley, Clarence W.; Griffin, John; Cattafesta, Louis N.; Hart, Adam; Ukeiley, Lawrence

doi:10.2514/6.2012-33

Cited by 23 publications

(32 citation statements)

References 32 publications

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“…25,26 This should permit the calculation of DMD modes to identify fixed-frequency flow structures. Then, unsteady pressure acquired simultaneously with PIV will estimate the time-resolved velocity field in a low-order manner.…”

Section: Discussionmentioning

confidence: 99%

Control of a canonical separated flow

Griffin

Oyarzun

Cattafesta³

et al. 2013

43rd Fluid Dynamics Conference

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A stalled airfoil can exhibit up to three natural frequencies associated with the separated flow: that of the shear layer, the separation bubble, and the wake. This work investigates these flow phenomena using a simplified canonical setup and targets their frequencies with zero-net mass-flux (ZNMF) actuation in order to effectively and efficiently reduce the extent of the separation. First, boundary layer separation is created on a flat plate model, devoid of curvature that would otherwise include effects particular to the type of aerodynamic body, by imposing an adverse pressure gradient via a ZNMF suction/blowing boundary condition on the tunnel ceiling. At a chord Reynolds number of 10 5 , the nominal two-dimensional characteristics of the flow are verified. The uncontrolled flow is characterized, including identification of the key flow frequency content, prior to strategically targeting this content with unsteady actuation. The identified natural frequencies of the shear layer and wake are then targeted via open-loop ZNMF sinusoidal and burst-modulated (BM) forcing. The results clearly indicate the ability to reattach the separated flow using significantly reduced Cµ values via BM forcing compared to sinusoidal forcing at the actuator resonance frequency.

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Section: Discussionmentioning

confidence: 99%

Control of a canonical separated flow

Griffin

Oyarzun

Cattafesta³

et al. 2013

43rd Fluid Dynamics Conference

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“…The method may also yield the estimation of the pressure, but requires the use of a higher-order SE model than for the velocity estimation (see Naguib, Wark & Juckenhöfel (2001); Murray & Ukeiley (2003); Hudy, Naguib & Humphreys (2007)), for which the linear SE (LSE) gives satisfactory results. Other more advanced methods, relying on similar techniques, have been introduced for instance by Tu et al (2013). They elaborated a three-step estimation approach for the unsteady field that uses down-sampled TR-PIV snapshots and point sensors.…”

mentioning

confidence: 99%

Unsteady flow dynamics reconstruction from mean flow and point sensors: an experimental study

et al. 2017

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This article presents a reconstruction of the unsteady behaviour of a round jet at a Reynolds number equal to 3300, from the sole knowledge of the time-averaged flow field and one pointwise unsteady measurement. The reconstruction approach is an application of the work of Beneddine et al. (J. Fluid Mech., vol. 798, 2016, pp. 485-504) and relies on the computation of the dominant resolvent modes of the flow, using a parabolised stability equations analysis. To validate the procedure, the unsteady velocity field of the jet has been characterised by time-resolved particle image velocimetry (TR-PIV), yielding an experimental reference. We first show that the dominant resolvent modes are proportional to the experimental Fourier modes, as predicted by Beneddine et al. (J. Fluid Mech., vol. 798, 2016, pp. 485-504). From these results, it is then possible to fully reconstruct the unsteady velocity and pressure fluctuation fields, yielding a flow field that displays good agreement with the experimental reference. Finally, it is found that the robustness of the reconstruction mainly depends on the location of the pointwise unsteady measurement, which should be within energetic regions of the flow, and this robustness as well as the quality of the reconstruction can be greatly improved by considering a few pointwise measurements instead of a single one. The effects of other experimental parameters on the reconstruction, such as the size of the interrogation window used for the TR-PIV processing and the accuracy of the positioning of the sensors, are also investigated in this paper.

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“…This combined usage of multi-time delay linear stochastic estimation of POD expansion coefficients is known as mtd LSE-POD. 16,17 When applied to a spatially-resolved fluctuating velocity field, POD provides a set of ortho-normal modes that are weighted based on the turbulent kinetic energy of the field. POD thus allows for the construction of a reduced order model of a high-dimensional velocity field, through a truncation of the modes.…”

Section: Physical Setupmentioning

confidence: 99%

“…As with traditional PIV, however, the flow field measurements are conducted at a low sampling rate compared to the relative time scales of the flow field. To circumvent this, a stochastic estimation technique 16,17 is implemented in which time-resolved surface pressure fluctuations that are synchronized with the lowfrequency sampled PIV data are used to generate an estimate of the time-resolved flow field. This flow-field estimate is then used to compute a low-order representation of components of the unsteady Lamb vector.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Characterization of Noise Generation on a Canonical Nose Landing Gear Sub-system

Zawodny

Dussault

Ukeiley

et al. 2013

19th AIAA/CEAS Aeroacoustics Conference

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A series of aeroacoustic experimental and computational measurements were conducted for the case of flow around a complex, three-dimensional landing gear sub-system. The model under study is a canonical representation of a nose landing gear torque link apparatus that is present on numerous commercial aircraft. Experimental measurements consisted of model steady and unsteady surface pressures, far-field acoustic measurements, and three-dimensional flow field velocities using stereoscopic particle image velocimetry. The experiments were also accompanied by computational fluid dynamics simulations using PowerFLOW software, a lattice-Boltzmann solver. The computational aeroacoustic capabilities of this software were also utilized to predict the far-field acoustic radiation via a built-in Ffowcs-Williams and Hawkings solver. Excellent agreement between the simulation and experiments have been obtained for surface pressure measurements, mean flow field behaviors, and far-field acoustics. A modified linear stochastic estimation procedure was implemented on the SPIV data to develop a low-order time-resolved estimate of the acoustic source terms of the vortex sound analogy.

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Integration of non-time-resolved PIV and time-resolved velocity point sensors for dynamic estimation of time-resolved velocity fields

Cited by 23 publications

References 32 publications

Control of a canonical separated flow

Control of a canonical separated flow

Unsteady flow dynamics reconstruction from mean flow and point sensors: an experimental study

Characterization of Noise Generation on a Canonical Nose Landing Gear Sub-system

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