Measurement of Turbulent Flow Phenomena for the Lower Plenum of a Prismatic Gas-Cooled Reactor
Mean velocity field and turbulence data are presented for flow phenomena in a lower plenum of a typical prismatic gas-cooled reactor (GCR), such as in a Very High Temperature Reactor (VHTR) concept. In preparation for design, safety analyses and licensing, research has begun on readying the computational tools that will be needed to predict the thermal-hydraulics behavior of the reactor design. Fluid dynamics experiments have been designed and built to develop benchmark databases for the assessment of computational fluid dynamics (CFD) codes and their turbulence models for a typical VHTR plenum geometry in the limiting case of negligible buoyancy and constant fluid properties. This experiment has been proposed as a “Standard Problem” for assessing advanced reactor (CFD) analysis tools. Present results concentrate on the region of the plenum near its far reflector wall (away from the outlet duct). The flow in the lower plenum can locally be considered as multiple jets into a confined cross flow - with obstructions. A model of the lower plenum has been fabricated and scaled to the geometric dimensions of the Next Generation Nuclear Plant (NGNP) Point Design. The model consists of a row of full circular posts along its centerline with half-posts on the two parallel walls to induce flow features somewhat comparable to those expected from the staggered parallel rows of posts in the reactor design. Posts, side walls and end walls are fabricated from clear, fused quartz to match the refractive-index of the working fluid so that optical techniques may be employed for the measurements. The experiments were conducted in the Matched-Index-of-Refraction (MIR) Facility at the Idaho National Laboratory (INL). The benefit of the MIR technique is that it permits optical measurements to determine complex flow characteristics in passages and around objects to be obtained without locating a disturbing transducer in the flow field and without distortion of the optical paths. The innovative advantage of the INL system is its large size, leading to improved spatial and temporal resolution compared to others. Light mineral oil is used as the working fluid. For the data reported a 3-D Particle Image Velocimetry (PIV) system is used. The measurements reveal complicated flow patterns that include several large recirculation areas, reverse flow near the simulated reflector wall, recirculation areas in the upper portion of the plenum and complex flow patterns around the support posts. Data that will be presented include three-dimensional PIV images of flow planes, data displays along the three coordinate planes (slices) and presentations that describe the component flows at specific regions in the model.
- Research Organization:
- Idaho National Lab. (INL), Idaho Falls, ID (United States)
- Sponsoring Organization:
- DOE - NE
- DOE Contract Number:
- DE-AC07-99ID-13727
- OSTI ID:
- 919553
- Report Number(s):
- INL/CON-07-12067; TRN: US0806431
- Resource Relation:
- Conference: Nuclear Reactor Thermal Hydraulics Conference 12 (NURETH-12),Pittsburgh, PA,09/30/2007,10/04/2007
- Country of Publication:
- United States
- Language:
- English
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