Phase-locking particle image velocimetry measurement of unsteady flow behaviors: Online dynamic mode decomposition using field-programmable gate array

2019 ◽  
Vol 31 (2) ◽  
pp. 025109 ◽  
Keyword(s):  
Particle Image Velocimetry ◽  
Unsteady Flow ◽  
Field Programmable Gate Array ◽  
Particle Image ◽  
Phase Locking ◽  
Dynamic Mode Decomposition ◽  
Dynamic Mode ◽  
Mode Decomposition ◽  
Image Velocimetry ◽  
Field Programmable

scholarly journals Tomographic Particle Image Velocimetry and Dynamic Mode Decomposition (DMD) in a Rectangular Impinging Jet: Vortex Dynamics and Acoustic Generation

Fluids ◽  
2021 ◽  
Vol 6 (12) ◽  
pp. 429
Author(s):  
Hassan H. Assoum ◽  
Jana Hamdi ◽  
Marwan Alkheir ◽  
Kamel Abed Meraim ◽  
Anas Sakout ◽  
...  
Keyword(s):  
Particle Image Velocimetry ◽  
Acoustic Field ◽  
Coherent Structures ◽  
Particle Image ◽  
Flow Dynamics ◽  
Dynamic Mode Decomposition ◽  
Dynamic Mode ◽  
Tomographic Particle Image Velocimetry ◽  
Mode Decomposition ◽  
Image Velocimetry

Impinging jets are encountered in ventilation systems and many other industrial applications. Their flows are three-dimensional, time-dependent, and turbulent. These jets can generate a high level of noise and often present a source of discomfort in closed areas. In order to reduce and control such mechanisms, one should investigate the flow dynamics that generate the acoustic field. The purpose of this study is to investigate the flow dynamics and, more specifically, the coherent structures involved in the acoustic generation of these jets. Model reduction techniques are commonly used to study the underlying mechanisms by decomposing the flow into coherent structures. The dynamic mode decomposition (DMD) is an equation-free method that relies only on the system’s data taken either through experiments or through numerical simulations. In this paper, the DMD technique is applied, and the spatial modes and their frequencies are presented. The temporal content of the DMD’s modes is then correlated with the acoustic signal. The flow is generated by a rectangular jet impinging on a slotted plate (for a Reynolds number Re = 4458) and its kinematic field is obtained via the tomographic particle image velocimetry technique (TPIV). The findings of this research highlight the coherent structures signature in the DMD’s spectral content and show the cross correlations between the DMD’s modes and the acoustic field.

scholarly journals Dynamic mode decomposition of inertial particle caustics in Taylor–Green flow

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Omstavan Samant ◽  
Jaya Kumar Alageshan ◽  
Sarveshwar Sharma ◽  
Animesh Kuley
Keyword(s):  
Turbulent Flows ◽  
Particle Image ◽  
Experimental System ◽  
Stokes Number ◽  
Dynamic Mode Decomposition ◽  
Dynamic Mode ◽  
Complex Structures ◽  
Inertial Particles ◽  
Mode Decomposition ◽  
Image Velocimetry

AbstractInertial particles advected by a background flow can show complex structures. We consider inertial particles in a 2D Taylor–Green (TG) flow and characterize particle dynamics as a function of the particle’s Stokes number using dynamic mode decomposition (DMD) method from particle image velocimetry (PIV) like-data. We observe the formation of caustic structures and analyze them using DMD to (a) determine the Stokes number of the particles, and (b) estimate the particle Stokes number composition. Our analysis in this idealized flow will provide useful insight to analyze inertial particles in more complex or turbulent flows. We propose that the DMD technique can be used to perform similar analysis on an experimental system.

Analysis of dynamic stall flow field of high bypass fan rotor based on airworthiness certification

2020 ◽  
Vol 234 (11) ◽  
pp. 1757-1769
Author(s):  
Kai Zhang ◽  
AJ Wang
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Field Data ◽  
Decomposition Methods ◽  
Modal Identification ◽  
Dynamic Mode Decomposition ◽  
Dynamic Mode ◽  
Complex Flow ◽  
Mode Decomposition ◽  
Proper Orthogonal

In order to ensure flight safety, the stall test is one of the most important steps in the airworthiness certification phase of civil aircraft. The twisted-swept fan is one of the most important components of the high bypass ratio engine. The unsteady flow field of the fan rotor stall condition is obtained by numerical simulation. At the same time, the time series flow field data of the stall condition flow field is acquired. The modal analysis of the unsteady flow field at stall condition was performed using the dynamic mode decomposition and proper orthogonal decomposition methods. Through modal identification of a large number of unsteady flow field data, the eigenvalues and corresponding modal information about the unsteady flow field change process are obtained. Finally, the evolution process of the unsteady flow field of the fan rotor under stall condition is visually demonstrated, and the coherent structures of different scales in the complex flow field under stall condition are revealed.

scholarly journals Simultaneous Measurement of Free Surface Elevation and Three-Component Velocity Field Around a Translating Surface-Piercing Foil

2018 ◽  
Vol 140 (3) ◽  
Author(s):  
James Schock ◽  
Jason Dahl
Keyword(s):  
Particle Image Velocimetry ◽  
Free Surface ◽  
Velocity Field ◽  
Numerical Methods ◽  
Flow Field ◽  
Particle Image ◽  
Laser Sheet ◽  
Three Dimensional ◽  
Dynamic Mode ◽  
Image Velocimetry

Two methods are investigated to simultaneously obtain both three-dimensional (3D) velocity field and free surface elevations (FSEs) measurements near a surface piercing foil, while limiting the equipment. The combined velocity field and FSE measurements are obtained specifically for the validation of numerical methods requiring simultaneous field data and free surface measurements for a slender body shape. Both methods use stereo particle image velocimetry (SPIV) to measure three component velocities in the flow field and both methods use an off the shelf digital camera with a laser intersection line to measure FSEs. The first method is performed using a vertical laser sheet oriented parallel to the foil chord line. Through repetition of experiments with repositioning of the laser, a statistical representation of the three-dimensional flow field and surface elevations is obtained. The second method orients the vertical laser sheet such that the foil chord line is orthogonal to the laser sheet. A single experiment is performed with this method to measure the three-dimensional three component (3D3C) flow field and free surface, assuming steady flow conditions, such that the time dimension is used to expand the flow field in 3D space. The two methods are compared using dynamic mode decomposition and found to be comparable in the primary mode. Utilizing these methods produces results that are acceptable for use in numerical methods verification, at a fraction of the capital and computing cost associated with two plane or tomographic particle image velocimetry (PIV).

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