Numerical Analysis of Transient Induced Flow Through Open Ended Tall Vertical Concentric Annulus

In this work, thermally induced water flow behavior in an open, tall, vertical annulus is carefully characterized using numerical analysis. The annuli in this study had aspect ratios of 1.184 and 352 (length to annular gap) (outer radius to inner radius). When constructing the machinery for nuclear reactor systems, the circular test sections with such a high aspect ratio are essential. The proprietary code employs a tried-and-true semi-implicit finite difference method as the numerical approach, which is based on the SMAC technique. The induced flow is brought on by a step change in the inner wall heat flux even while the exterior wall is assumed to be adiabatic. The Raleigh number (Ra) ranges from 1.1 × 104 to 6.6 × 105, although the Prandtl number (Pr) is 6.43. The research examines the impact of heating on the mass flow rate, pressure drop, and heat transfer coefficient among other design parameters. Along with the outcomes, a time- and location-based temperature and velocity profile is given. Additionally taken into account are the temporal fluctuations in induced flow and pressure distribution along the annulus.