Investigation on performance of ejectors with adjustable nozzles.

In this study, the performance characteristics of adjustable nozzles were experimentally investigated. In these nozzles, a spindle is used to control the cross-sectional area of the ejector nozzle throat, and magnetic force is used to control the position of the spindle. The change in the throat area and the controller input for the spindle were found to have a nearly linear relationship. In the experiment, the generating pressure was set to 1.9 MPa, and the back pressure was set to 0.83 MPa. A de Laval nozzle and a converging nozzle with the same throat dimensions were used in the experiment. In the results, both ejectors showed peak performances as the throat area was changed. The de Laval nozzle performed better at its peak condition, but its performance quickly dropped under off-design conditions. In contrast, the converging nozzle showed only slight changes to the performance as it was adjusted with a lower peak performance. The converging nozzle is recommended for realizing a more stable change in performance by an adjustable ejector.

本研究针对可调式喷嘴的性能特性开展了实验研究。该类喷嘴通过调节轴控制引射喷嘴喉部的横截面积，并利用磁力调控调节轴的位置。研究发现，喉部面积的变化量与调节轴的控制器输入量之间近乎呈线性关系。实验中，设置工作压力为1.9 MPa，背压为0.83 MPa。本实验选用了喉部尺寸一致的拉瓦尔喷嘴（de Laval nozzle）与收敛喷嘴。实验结果显示，随着喉部面积的调整，两种引射器均出现了性能峰值。拉瓦尔喷嘴在峰值工况下性能更优，但在非设计工况下其性能会快速衰减。与之相比，收敛喷嘴的峰值性能更低，且调节过程中其性能仅发生小幅变化。综上，若采用可调式引射器实现性能的稳定调节，推荐选用收敛喷嘴。