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Communication Dans Un Congrès Année : 2022

Simultaneous control rod 3D displacement and 3D flow measurements via time resolved 3D3C PTV with one camera only

Résumé

In the framework of Flow-Induced Vibration (FIV), the measuring capability of a time-resolved 3D-3C Particle Tracking Velocimetry (PTV) with one camera only is addressed in this paper. The study deals with a representative turbulent flow (Re = 3.10 4) around guide plates and simulated control rods as parts of a nuclear CRGA (Control Rod Guide Assembly). Based on image defocus, this 3D3C PTV transforms the scattered light of laser-illuminated seeding particles into circular patterns on the defocused images. A patented annular pupil device is used in this scope. These particle patterns are detected and tracked over time by PTV in order to provide instantaneous 3D velocity fields. 3D3C PTV velocities are validated by comparison with LDV data for both spatial (mean and standard deviation of velocity) and spectral (PSD) domains to confirm the accurate capture of the flow dynamics. The measures are found to be consistent in both shape and amplitude. The 3D3C PTV measurements are even more refined than LDV near the rods for the main axial flow. An easy, non-intrusive in-situ calibration based on a laser sheet sweep along the camera's in-depth direction completes the technique. The time required to post-process 20 000 images (time points) is less than 24 h on an HP Z820 workstation with 24 cores, and more than 1000 particles can be tracked per image over time to create trajectories. Simultaneously, the 3D displacement of moving rods is recorded on these images (one camera only). Tracer particles are indeed fixed on the moving rods to track the rod FIV. Two moving rods are scrutinized in the upstream vicinity of a guide plate: one "free rod" is submitted to flexion with pinnedpinned boundary conditions, and another is held by strings in the highest cross-flow velocity region. With the same set of defocused images, the technique describes then both the excitation (flow) and the rod response (displacement) at the same time, leading to the whole Fluid-Structure Interaction (FSI) or the structure transfer function (response/excitation) with one camera only. The missing step that remains will be to reconstruct instantaneous pressure fields from 3D3C particle trajectories to reach the fluid loads applied to the structure (here rods). Previous works were already undertaken at Technical Center Framatome in 2014 to meet this objective.
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Dates et versions

hal-03820406 , version 1 (20-11-2022)

Identifiants

  • HAL Id : hal-03820406 , version 1

Citer

Vincent Fichet, Mouad Daoudi, Laurent Zimmer. Simultaneous control rod 3D displacement and 3D flow measurements via time resolved 3D3C PTV with one camera only. 12th International Conference on Flow-Induced Vibration, Jul 2022, Saclay, France. ⟨hal-03820406⟩
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