Unsteady Elbow Pipe Flow to Develop a Flow-Induced Vibration Evaluation Methodology for Japan Sodium-Cooled Fast Reactor

Abstract

This paper describes the current status of flow-induced vibration evaluation methodology development for primary cooling pipes in the Japan sodium-cooled fast reactor (JSFR), with particular emphasis on recent research and development activities that investigate unsteady elbow pipe flow. Experimental efforts have been made using 1/3-scale and 1/10-scale single-elbow test sections for the hot-leg pipe. The 1/10-scale experiment simulating the hot-leg pipe indicated no effect of pipe scale in comparison with the 1/3-scale experiment under inlet-rectified-flow conditions. The next experiment using the 1/3-scale test section was performed to investigate the effect of swirl flow at the inlet. Although the flow separation region was deflected at the downstream from the elbow, the experiment clarified a less significant effect of swirl flow on pressure fluctuation onto the pipe wall. An additional experiment was intended to study the effect of elbow curvature. The experiments with water revealed no clear flow separation in a larger curvature elbow case than that of the JSFR. Since the interference of multiple elbows should be investigated to understand turbulent flow in the cold-leg pipe geometry, 1/15-scale experiments with double elbows were carried out to clarify that flow in the first elbow influenced a flow separation behavior in the second elbow. Simulation activities include Unsteady Reynolds Averaged Navier Stokes equation (U-RANS) approach with a Reynolds stress model using a commercial computational fluid dynamics (CFD) code and Large Eddy Simulation (LES) approach using an in-house code. A hybrid approach that combined with RANS and LES was also applied using a CFD code. Several numerical results appear in this paper, focusing on its applicability to the hot-leg pipe experiments. These simulations reasonably agreed with the experimental data using the 1/3-scale test section.

Investigation of the effects of pipe diameter of internal multiphase flow on pipe elbow vibration and resonance

“…Most of the reported literature on FIV in pipe bends in large pipes are for nuclear power plant applications. 12 Yamano et al 13 results prove that both pipe size and configuration have effects on MFIV characteristics. The cost and hazard of comprehensive life scale experiments of oil and gas and nuclear power plant pipework could be prohibitive.…”

“…5 Their findings on the relationship between the nondimensional force fluctuation and Weber number compared fairly to the model by Riverin et al 11 and data from Liu et al 3 Most of the reported literature on FIV in pipe bends in large pipes are for nuclear power plant applications. 12 Yamano et al 13 results prove that both pipe size and configuration have effects on MFIV characteristics. The cost and hazard of comprehensive life scale experiments of oil and gas and nuclear power plant pipework could be prohibitive.…”

“…Studies have applied U-RANS approach to capture the mechanism of FIV in large pipe bends due to pressure fluctuations, dominant in single-phase flows. 12,13,17 In general, the risk of FIV increases in multiphase flows. 18…”

Random Forest Regression-Based Machine Learning Model for Accurate Estimation of Fluid Flow in Curved Pipes

“…When compared to straight pipes, the main feature of curved pipes is the presence of a secondary motion consisting of a pair of symmetric, counter-rotating vortices. This Prandtl first kind secondary motion increases heat transfer and mixing, for example, effects that are used in many industrial applications, such as nuclear reactor cooling systems, and food processing [1][2][3].…”

Numerical Study about the Change in Flow Separation and Velocity Distribution in a 90o Pipe Bend with/without Guide Vane Conditions

“…Pipe bends can be used as a part of several mechanical systems, e.g. heat exchangers (Chang, 2003) reciprocating engines (Hellström, 2010) and nuclear reactors (Yamano et al, 2011). Pipe bends are also used in the oil industry, water supply systems, for fluid and material transportation and to change the direction of flow.…”