Large eddy simulation of a flow inside a helical coil steam generator test section for a small modular reactor
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abstract
2016 Association for Computing Machinery Inc. All Rights Reserved. For the purpose of increasing the thermal efficiency with a relatively low thermal expansion, helical coil steam generators (HCSGs) have been employed on various types of engineering applications. In particular, due to their compactness, a recent design of the small modular reactor (SMR) has adopted the HCSG as its heat exchanger placed in between a reactor core and surrounding coolant. In order to ensure the safe and reliable operation of a nuclear reactor, the investigation of the characteristics of flow fields around the helical coil bundle is essential. To understand how the flow field of the coil bundle region affect the pressure distribution on the helical coil surface is crucial for determining the reactor operating condition. To examine the flow phenomena around a bundle of the HCSG, the experimental facility has been designed and installed. The test section inside the facility had a single-layer flow channel of the helical coil bundle. The half-coil shaped ribs were placed on both concavely and convexly curved channel walls. In this study, computational fluid dynamics (CFD) simulations were conducted on the test section geometry. The working fluid properties employed in the simulation were matched with the room temperature as in the experiment. Based on the fluid properties, the channel height inside the test section and the mean streamwise velocity, the Reynolds numbers were estimated between 28,500 and 163,000. The CFD simulations performed were solving the unsteady three-dimensional incompressible Navier-Stokes equations using the LES model. Both transient and statistically averaged variables, such as velocity and pressure, were monitored on the same measurement positions as in the experiment. The averaged pressure drop induced by the helical coil bundle shaped channel was obtained between the inlet and the outlet of the test section. The flow patterns around the helical coil were investigated by analyzing the velocity field distribution inside the flow channel. The flow visualization methods were also employed to understand the effect of vortical structures which affected the pressure distribution on the surface of the helical coil bundle.
published proceedings
17th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2017
