刷式密封临界承压能力流固耦合数值研究

Numerical study on fluid-structure interaction of critical pressure capacity of brush seal

采用以泄漏因子与有效间隙作为刷式密封临界承压能力的评价指标,基于ALE(arbitrary Lagrange-Euler)流固耦合方法建立刷式密封三维瞬态求解模型,分析三种不同结构的刷式密封模型在不同压差下的刷丝变形,研究临界承压能力对刷丝变形的影响。研究结果表明:随着上下游压差的增加,泄漏因子与有效间隙的值趋于稳定时的压差范围即为刷式密封的临界承压能力。所研究的基本型刷式密封临界承压能力为0.25~0.30 MPa,后挡板保护高度降低0.5 mm的刷式密封和轴向增加5排刷丝的刷式密封临界承压能力相对于基本型增加了16.7%~20.0%,降低后挡板保护高度和增加刷丝轴向排数可以提高刷式密封临界承压能力。随着上下游压差的增加,刷丝轴向最大变形量先增加,在上下游压差达到刷式密封临界承压能力时,刷丝之间间隙被压缩至接近最小,刷丝轴向最大变形量达到稳定。该研究成果为刷式密封的结构设计提供理论依据。

Leakage factor and effective clearance were used as the evaluation indexes of the critical pressure capacity of brush seals. A three-dimensional transient solution model of brush seals was established based on the ALE(arbitrary Lagrange-Euler) method. Three brush seal models with different structures were studied, and the brush wire deformation under different pressure differences was analyzed.The influence of critical pressure capacity on wire deformation was obtained. The results showed that with the increase of the pressure difference between the upstream and downstream, the maximum pressure difference between the leakage factor and the effective clearance was prone to be the critical pressure capacity. The critical pressure capacity of the basic brush seal was about 0.25—0.30 MPa. Compared with the basic brush seal, the critical pressure capacity of the brush seal with the rear damper protection height reduced by 0.5 mm, and that of the brush seal with the axial increase of 5 rows of brush wire increased by16.7% to 20.0%. The critical pressure capacity of the brush seal can be improved by decreasing the rear damper protection height and increasing the number of axial rows of the brush wire. With the increase of the pressure difference between the upstream and downstream, the maximum axial deformation of the brush increased first. When the pressure difference between the upstream and downstream reached the critical pressure capacity of the brush seal, the gap between the brushes was compressed to the minimum,and the maximum axial deformation of the brush reached the maximum. The research results provide a theoretical basis for the structural design of brush seal.