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

为了实现具有高等熵效率的超音速闭式(非平衡)盘式磁流体发电机，需要提高产生通道和扩散器的效率。考虑到这一事实，我们开展了以下研究。首先，我们开发了一个考虑边界层影响的超音速闭式盘式磁流体发电机的二维设计计算程序。由于干流和边界层的电场强度通常几乎相同，因此采用恒定电场强度作为补充条件，在不将流分成干流和边界层的情况下，在包含边界层的平面上进行设计计算，并将该条件应用于整个发电机。它可以确定实际的发电机配置和包括边界层在内的详细的二维质量分布。接下来，我们来治疗一个大规模的高性能…采用能量为100 mW的铯种子氦等离子体，研究了扩散器背压对发电机性能的影响，并对产生通道和扩散器两个区域进行了详细的二维时变数值分析。在模拟程序中，气体动量分布采用Chakravarthy和Osher提出的TVD格式计算。研究表明，通过合理选择扩散器背压，可以实现包括扩散器区域在内的高性能运行和高等熵效率。发生器的性能受背压的影响，其最高性能运行按设计要求进行，通过选择扩散器可以获得包括扩散器区域在内的高等熵效率，但在背压较低和高于适当值的两种情况下都不能获得最高的可能性能。较少

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