End effect of liquid metal magnetohydrodynamic generator in wave energy direct conversion system

The influence of end effect on electromotive force, induced magnetic field and flow loss of the reciprocating liquid metal magnetohydrodynamic (LMMHD) generator was investigated. The 3D numerical simulation was done firstly, then the electromagnetic and flow performances predicted from quasi-2D and 3D analyses were compared and three end influence coefficients quantifying end effect were defined. Factors influencing end effect were analyzed and new method to suppress the end effect was proposed in the end. The study shows that the end gradient of the external magnetic field and end leakage current are main causes of the end effect in the LMMHD generator. The velocity in MHD channel and end gradient of the applied magnetic field are two key factors affecting the end effect greatly. The integration of insulating vane and low end gradient of the applied magnetic field can effectively suppress the end current and decrease energy losses.