刷式密封刷丝变形与振动特性实验

刷式密封刷丝运动变形引起的泄漏损失、刷丝断裂等问题较为突出。本文分析刷式密封刷丝运动变形理论模型，设计搭建刷式密封刷丝变形与振动特性观测实验装置，设计加工了3种周向倾角的低滞后型刷式密封实验件，实验观测并研究刷式密封刷丝轴向变形特性，刷丝吹下效应、刷丝分层和刷丝振动特性，揭示刷式密封刷丝运动状态。研究结果表明，在进出口压比1.5~4工况下，刷式密封刷丝自由端轴向变形量随着压比的增大而近似线性增加，周向倾角对刷丝轴向变形影响不大。刷式密封前排刷丝吹下效应明显强于后排刷丝，随着周向倾角的增大，刷式密封刷丝吹下效应逐渐减弱，在本文研究工况下，周向倾角为50°、55°和60°的刷式密封刷丝最大吹下量分别为0.60、0.45和0.34 mm。刷式密封刷丝产生分层现象的主要原因是在气流力的作用下，刷丝束轴向产生变形，刷丝束自由端在不相等的转子表面轴向摩擦力作用下，刷丝束进一步产生不同步的变形量，导致刷丝束出现间隙进而形成刷丝分层现象。刷丝振动主要发生在刷丝密度相对松散的区域，且随着压比的增大而增强，刷丝自由端位移随时间呈振荡变化，其在轴向的振幅大于周向的振幅。

Experiment on bristle deflection and oscillation characteristics of brush seals

The problem of the leakage and bristle fracture produced by the bristle deflection and oscillation of brush seals is very prominent. In this paper, the theoretical model of the bristle deflection and oscillation of brush seals is analyzed, the device of observation experiment for the bristle deflection and oscillation characteristics of brush seals is designed. Experimental pieces of brush seals for low hysteresis at three circumferential inclination angles are designed and processed. Moreover, the bristle axial deflection characteristics, bristle blow down effect, bristle stratification, and bristle oscillation characteristics are experimentally observed and studied, revealing the bristle movement of brush seals. The results show that the axial deflection of the bristle tips increases linearly with the increase of the pressure ratio when the inlet-to-outlet pressure ratios are between 1.5 to 4, and the circumferential inclination angles have little effect on the bristle axial deflection. The blow down effect of the front row is significantly stronger than that of the rear row. Under the research conditions of this paper, the maximum amount of bristle blow down of brush seals with circumferential inclinations angles of 50°, 55° and 60° is 0.60, 0.45 and 0.34 mm respectively. With the increase of the circumferential inclination angle, the blow down effect is gradually weakened. Under the influence of the air force, brush seals bristle produces axial deflection, and the bristle tips are subject to the unequal axial frictional force of the rotor surface. Brush seals bristle produces unequal axial deflection, resulting in large gaps inside the bristle pack, and forming bristle stratification. The bristle oscillation mainly occurs in the region where the bristle density is relatively loose, and with the increase of the pressure ratio, the displacement of the bristle tip is oscillating. Its amplitude in the axial direction is greater than that in the circumferential direction.