Suppression of Total Pressure Loss in Vanes for Supersonic Swirl Flow Generation

为了提高盘式磁流体发电机的性能，建议在发电机通道入口处安装进口旋流叶片，在超音速惰性工作气流中引入方位速度分量。针对目前使用的对称喷嘴旋流叶片存在的喷嘴设计不完善导致流场周向不均匀性增大的问题，本研究首先分析了旋流叶片周围的流场和流体动力损失机理，然后提出了一种新的非对称喷嘴设计方案，旨在获得周向均匀的旋流速度场和较低的压力损失。通过风洞试验验证了这些采用非对称喷嘴的新型旋流导叶的性能，并通过二维湍流数值模拟从流场均匀性的角度评价了这些设计方法的技术有效性。最后讨论了用于盘式磁流体发电机的喷嘴的优化设计。

To improve the performance of disk MHD generators, it is suggested to install inlet swirl vanes to introduce azimuthal velocity component in the supersonic inert working gas flow at the inlet of the generator channel. But, currently used swirl vanes employing symmetric nozzles has a problem that flow field non-uniformity in azimuthal direction grows due to incompleteness of the nozzle design.This research first analyses the flow field around the swirl vanes and the mechanism of the fluid dynamical loss, then proposes a new asymmetric supersonic nozzle design for swirl vanes aiming at achieving the azimuthal uniformity swirling velocity field with low pressure loss. The performance of these newly designed swirl vanes using asymmetric nozzles is confirmed by wind-tunnel experiments.Technical validity of these design methods from the viewpoint of flow field uniformity is evaluated by numerical simulation of two-dimensional turbulent flow. Finally, design optimization of the nozzles is discussed for introduction to disk MHD generators.