Experimental investigations on liquid metal MHD turbulent flows through a circular pipe with a conductive wall

摘要

Highlights•Experimental investigation on a turbulent MHD conductive pipe flow under a transversal uniform magnetic field at high Hartmann and Reynolds numbers is conducted.•The results of the mean and the transient velocity distribution, turbulent Reynolds stress and a laminar-turbulent transition map are presented.•High velocity jets are not observed from the experiment. The velocity distribution agrees with former numerical results.•A type of instability is observed from experiment and the laminar-turbulent transition condition is Rec/Ha>20.AbstractExperimental results on a liquid metal magnetohydrodynamic (MHD) turbulent flow through a circular conductive pipe subject to a uniform transversal magnetic field are summarized in this paper. The results of the MHD turbulent velocity distributions inside the conductive pipe are obtained. The velocity profiles along the center line of the middle cross section of the pipe are given. There are no big velocity jets in the Robert layers. The velocity distribution agrees well with the numerical simulation result. The transient turbulent velocity of one point in above mentioned line changing with times are measured in the experiment, it is found that the transient velocity varies dramatically compared to the average velocity at high Reynolds number (Re). The strong magnetic field suppresses the turbulent velocity fluctuation. The velocity profiles varying with the different Reynolds numbers at the same Hartmann number (Ha) are also presented in this paper. It is shown that the velocity in the center fluid area decreases with the Reynolds numbers increasing. The Reynolds stresses at different Reynolds numbers and Hartmann numbers are also derived from experimental data. The Reynolds stresses decrease with the increasing of Hartmann numbers. The map of laminar-turbulent transition for MHD circular conductive pipe flows at high Reynolds and Hartmann numbers are also presented. A different fluid instability from the theoretical prediction in Refs. Lielausis (1975) and Moresco et al. (2004) is observed and the transition condition is Re/Ha>20.