Numerical research on strengthening secondary flow of tokamak in-vessel coils' water-cooling pipe joints

The tokamak in-vessel coil water-cooling pipe joints of different deflector curvature radius ratios are studied based on the computational fluid dynamics (CFD). The impact on the average Reynolds number distribution from the coils water-cooling pipe of different ratio of the coil pipe joint deflector curvature radius and related inlet velocity has been analyzed, using turbulence numerical simulation method. The results indicate that the average Reynolds number distribution curves of different deflector curvature radius ratio are similar, and the numbers increase with the increase of inlet velocity, while the outlet Reynolds numbers of the pipe joint decrease with the increase of the deflector curvature radius ratio. The deflector of the small curvature radius ratio is more suitable for the secondary flow enhancement of the coil water-cooling curved pipe. In addition, the relationship between the outlet Reynolds numbers of the coil joint and its inlet velocity is fitted for the pipe joint with deflector curvature radius ratio of 0.2, which provides a theoretical basis for further study of the secondary flow enhancement of the similar curved pipe joint with tokamak in-vessel coil pipe. (authors)