IMPROVEMENT ON ISENTROPIC EFFICIENCY OF PLASMA MHD GENERATOR BY HELIUM

本研究的目的是提高等离子体MHD发生器的等熵效率，期望提供非常高的热效率。在2000财政年度，在超音速喷嘴中的等离子体形成的实验研究。实验结果表明，等离子体的形成是困难的，在低种子分数和依赖于喷嘴负载电阻。此外，有人建议，冲击波出现，因此，流速显着降低，在高种子分数，虽然等离子体的形成变得容易。结果，焓提取仍然很小，仅为9%。在2001财政年度，优化了喷嘴负载阻力，焓提取从9%增加到14%。同时，功率输出增加到650 kW，并证实了氦气中高流速的优势。等熵效率也得到了显着提高，测得的电压-电流曲线显示更高的电压相比，氩气。在财政年度2002年，操作条件进一步优化，并引入了一个入口涡流。因此，焓提取增加到30.3%，等熵效率显著提高（= 63%）。还获得了1200 kW的大功率输出。这些结果是世界上所有实验数据中最高的。这些结果鼓励我们进行下一步。下一步，我们计划利用超音速闭环实验装置研究等离子体磁流体发电机在长时间运行下的性能。

The objective of present study is to improve the isentropic efficiency of the plasma MHD generator which is expected to provide very high thermal efficiency.In the fiscal year 2000, the plasma formation in the supersonic nozzle was investigated experimentally. The experimental results indicated that the plasma formation is difficult at low seed fractions and depends on nozzle load resistance. Furthermore, it is suggested that the shock wave appears and as a result, the flow velocity is reduced significantly at high seed fractions, although the plasma formation becomes easy. As a result, the enthalpy extraction remained small and it was only 9 %.The nozzle load resistance was optimized in the fiscal year 2001 and the enthalpy extraction increased from 9 % to 14 %. At the same time, the power output increased up to 650 kW and the advantage of high flow velocity in helium was confirmed. The isentropic efficiency was also improved significantly and the measured voltage-current curve showed higher voltage compared with that for argon.In the fiscal year 2002, the operating condition was optimized further and an introduction of an inlet swirl was adopted. Therefore, the enthalpy extraction increased up to 30.3 % and the isentropic efficiency was remarkably improved (=63 %). The large power output of 1200 kW was also obtained. These results are the highest among all experimental data in the world.These results have encouraged us to proceed to the next step. In the next step, we have a plan to investigate performances of plasma MHD generator under long operation time using the supersonic closed loop experimental facility.