MHD pressure drop of Nak flow in a coaxial double circular duct and a plane-insulated duct under transverse magnetic fields

In order to gain basic information on the MHD pressure drop for applying to fusion power reactors, two types of experiments were conducted in use of NaK. In a coaxial double circular duct experiment (U=0.05-1.0m/s and B=0-1.5T), the pressure drop of core NaK forced flow was measured in the presence of NaK in the annular channel. The inner and outer ducts are 25.4mm O.D. and 0.5mm thick and 38.1mm O.D and 1.0mm thick 304-SS tubes, respectively. The measured pressure drop was 3.6 times larger than the predicted value in the absence of annular NaK but 3.9 times smaller than the predicted value for annular solid NaK. In a plane-insulated circular duct experiment (U=0.1-1.4m/s and B=0-1.4T), an insulator of 1.0mm thick and 21.2mm wide FRP sheet was inserted into a 25.4mm O.D. and 2.1mm thick 304-SS tube. The MHD pressure drop was reduced nearly to a half of the predicted value for the case without the insulator