Numerical study on leakage flow characteristics of novel two-stage pressure equalizing brush seal
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摘要:
多级刷式密封存在各级级间压降分配不均衡导致提前失效的问题,提出下游级后挡板开孔的两级均压刷式密封结构,建立三维实体两级均压刷式密封数值计算模型,在验证数值模型准确性基础上,数值分析两级均压刷式密封的泄漏流动特性,研究均压孔结构参数对改进型结构泄漏特性和级间压降均衡性的影响规律。研究结果表明:设有均压孔的两级均压刷式密封较传统结构提高了压降均衡性,且降低了刷式密封摩擦热效应;传统两级刷式密封的压降均衡性系数明显大于两级均压刷式密封,改进型结构的压降均衡性系数较传统结构改善了45.6%~67.9%;均压孔直径从0.2 mm增大至0.8 mm、均压孔高度从3.55 mm增大至8.35 mm与均压孔排数设置为3排时压降均衡性系数分别减小38.5%、7.7%和25.1%;改进型结构泄漏量相比于传统结构略有增大,且泄漏量随均压孔直径的增大而增加,随均压孔高度的提高无明显变化,随均压孔排数的增加而增大。
Abstract:The multi-stage brush seal has the problem of premature failure due to the uneven distribution of pressure drop between different stages. A new two-stage pressure equalizing brush seal structure with the opening of the downstream backsplash was proposed, and a three-dimensional entity numerical calculation model of the new two-stage pressure equalizing brush seal was established. On the basis of verifying the accuracy of the numerical model, the leakage flow characteristics of the new two-stage pressure equalizing brush seal were analyzed numerically. The influence of pore parameters on the leakage characteristics of the new structure and the balance of pressure drop between stages was studied. The results showed that the new two-stage pressure equalizing brush seal with pressure equalizing hole improved the pressure drop equalization and reduced the friction heat effect of the brush seal compared with the traditional structure. The pressure drop equilibrium coefficient of the traditional two-stage brush seal was obviously greater than that of the new two-stage brush seal, and the pressure drop equilibrium coefficient of the new structure was improved by 45.6%—67.9% compared with the traditional structure. When the diameter of pressure equalizing hole increased from 0.2 mm to 0.8 mm, the height of pressure equalizing hole increased from 3.55 mm to 8.35 mm, and when the number of pressure equalizing hole rows was set to 3, the pressure drop equilibrium coefficients decreased by 38.5%, 7.7% and 25.1%, respectively. The leakage amount of the new structure was slightly larger than that of the traditional structure, and the leakage amount increased with the increase of the diameter of the pressure equalizing hole, but had no obvious change with the increase of the height of the pressure equalizing hole, and increased with the increase of the number of pressure equalizing hole rows.
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表 1 两级均压刷式密封结构参数
Table 1. Structural parameters of two-stage pressure equalizing brush seal
mm 结构参数 数值 前挡板保护高度Hf 8.4 后挡板保护高度Hb 1.5 刷丝直径D 0.08 刷丝排列间距d 0.008 刷丝束轴向厚度W 1.5 刷丝束径向长度l 10.4 前挡板宽度Lf 1.5 后挡板宽度Lb 2 级间距Wd 10 均压孔直径Dj 0.2~0.8 均压孔高度Hj 3.55~8.35 -
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