Study on improvement of isentropic efficiently of closed cycle disk MHD generator

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To realize supersonic closed-cycle (nonequibrium) disk MHD generators with high isentropic efficiency, improvement of the efficiency in both the generation channel and the diffuser is necessary. Considering this fact, we carry out the following studies. At first, we newly developing a two-dimensional design calculation code of supersonic closed-cycle disk MHD generators which takes the effects of the boundary layer into consideration. Since the electric field strength usually takes almost the same vale in both the main flow and the boundary layer, constant electric field strength is adopted as a supplementary condition and the design calculation on the plane including the boundary layer without dividing the flow into the main flow and the boundary layer is realized by applying this condition all over the generator. It can determine the actual generator configuration and detailed two-dimensional quality distributions including the boundary layer. Next, we treat a large-scale high-perfor … More mance supersonic closed-cycle disk MHD generator using cesium-seeded helium plasma with 100MW thermal input, and investigate the effect of the diffuser back pressure on generator performance through detailed two-dimensional time-dependent numerical analyses for the region which includes the generation channel and the diffuser. In the simulation code, the gas dynamical quantity distributions are calculated by the TVD scheme proposed by Chakravarthy and Osher. It is made clear that high performance operation as designed and high isentropic efficiency including the diffuser region can be achieved by choosing the diffuser back pressure appropriately. The generator performance is influenced by the back pressure and its highest possible performance operation as designed and high isentropic efficiency including the diffuser region can be achieved by choosing the diffuser its highest possible performance can not be achieved in both the cases the back pressure is lower and higher than appropriate value. Less