齿间凸起对直通篦齿封严特性影响的数值研究

Numerical Investigation of Protrusions on Leakage of Straight-Through Labyrinth Seal

关键词:  直通篦齿  密封  衬套  凸起  泄漏系数  数值研究

Key words:  Straight-through labyrinth seal  Seal  Bush  Protrusion  Leakage coefficient  Numerical investigation

摘要:

为提升篦齿的密封性能，对在齿间光滑衬套上增加矩形凸起的直通篦齿的流动特性进行了数值研究，分析了压比、凸起的尺寸和轴向位置对篦齿泄漏特性的影响。和光滑齿相比，凸起破坏了壁面射流附面层的连续性，改变了流体在齿腔中的流动方向，有效地提高了通道的密封性能，降低了通道的泄漏量。结果表明，当压比为2时，含有凸起结构的篦齿的泄漏系数较光滑齿降低了13%，当压比增加到4时，泄漏系数更是降低了18%；凸起的高度越大宽度越小，凸起对篦齿密封性能的提高就越明显；凸起和下级齿之间的轴向距离越短，凸起对流入下级齿的气体流动方向改变就越大，密封性能也就越好。

Abstract:

To improve the performance of labyrinth seal，a straight-through labyrinth seal with protrusions on the smooth bush has been numerically investigated. The effects of pressure ratio，protrusions size and the space between teeth and protrusions are studied. Compared with smooth bush straight-through labyrinth seal，protrusions destroy the wall jet boundary layer continuity and change the direction of the jet flow，which improve the seal performance and decrease the mass flow effectively. The study reveals that when the pressure ratio is 2，the leakage coefficient of labyrinth seal with protrusions can decrease by 13% in comparison with smooth bush labyrinth seal，and when the pressure ratio is 4，the leakage coefficient is reduced by 18%. The narrower width and the higher height the protrusions can have，the better seal performance the labyrinth seal can get. Additionally，with a decrease of the axial distance between protrusion and the next tooth，the protrusion can greatly change the direction of the jet which flows into the next tooth，and thus improve the seal performance evidently.