多级刷式密封级间压降分配影响因素数值与实验研究

多级刷式密封级间压降分配直接影响刷式密封的封严特性和使用寿命，现有多级刷式密封结构存在各级压降不均衡导致密封提前失效的问题。本文建立多级刷式密封三维实体流固耦合求解模型，设计搭建多级刷式密封实验装置，在数值计算与实验测试结果相互验证的基础上，研究了工况参数与结构参数对多级刷式密封级间压降分配的影响规律，揭示了多级刷式密封级间压降不均衡性的产生机理。研究结果表明：在本文研究工况下，相同结构的两级刷式密封各级压降占比分别为32%~35%和65%~68%，三级刷式密封各级压降占比分别为21%~27%、27%~32%、41%~52%，多级刷式密封各级承担压降逐级增大，进出口压比对级间压降分配影响不大；增大刷丝束与转子表面间径向间隙、刷丝之间间隙以及后挡板高度均可改善各级压降分配，同时也会增加泄漏量；影响多级刷式密封级间压降均衡性的主要原因是逐级不均匀增大的体积流量，各级压降随体积流量逐级不均匀的增加而增大；增大下游级流道截面积可有效降低体积流量，平衡多级刷式密封各级压降。本文研究结果为多级刷式密封结构设计提供了理论依据。

Numerical and experimental research on interstage pressure drop distribution affecting factors of multi-stage brush seals

The pressure drop distribution between the multi-stage brush seals directly affects the seal characteristics and the service life of the brush seals. The existing multi-stage brush seals structure have the problem that the pressure drop is unbalanced at different stages, leading to premature seal failure. In this paper, a three-dimensional fluid-solid interaction multi-stage brush seals model is established, and a multi-stage brush seals experimental device is designed. Based on the mutual verification of numerical calculation and experimental test results, the influence law of working condition parameters and structural parameters on the interstage pressure drop distribution of multi-stage brush seals is investigated. The mechanism of interstage pressure drop imbalance of multi-stage brush seals is revealed. The results show that under the research conditions in this paper, the pressure drop ratio of the two-stage brush seals of the same structure are 32%-35% and 65%-68%, and the pressure drop ratio of the three-stage brush seals are different:21%-27%, 27%-32%, 41%-52%. The pressure drop of the multi-stage brush seals is gradually increased, and the pressure ratio of the inlet and outlet has little effect on the distribution of interstage pressure drop. By increasing the radial gap between the bristle tow and the rotor surface, the gap between the bristles and the height of the backplate can improve the pressure drop distribution of each level, and the amount of leakage will also increase. The main reason that affects the pressure drop balance of the multi-stage brush seals is the uneven increase of volume flow rate step by step, and the pressure drop of each stage increases with the increase of the volume flow unevenness step by step. Increasing the cross-sectional area of the downstream level can effectively reduce the volume flow rate and balance the pressure drop between multi-stage brush seals. The research results in this paper provide a theoretical basis for the design of multi-stage brush seals structure.