齿型对压气机级间封严特性影响的实验研究

Experimental Investigation for Effects of Tooth Shapes on Compressor Inter-Stage Seal

关键词:  级间封严  篦齿  旋转盘腔  流量系数  风阻温升  旋流

Key words:  Inter-stage seal  Labyrinth  Rotating cavity  Discharge coefficient  Windage heating  Swirl flow

摘要:

为了对比不同齿型下压气机级间封严特性，对基准常规齿、直通针型齿、直通宝塔齿和台阶斜齿时的级间篦齿封严进行了实验研究。在压比1.05～1.30，转速0～8.1kr/min时对不同齿型的工作间隙、泄漏流量、风阻温升和出口盘腔的旋转比进行了测量。基准常规齿是级间最常用的篦齿结构，将其他三种齿型下级间封严的泄漏特性、温升特性和旋流特性与其进行对比。结果表明:随着齿顶间隙的增大，基准常规齿的流量系数先增大后减小，在间隙c=0.8mm附近有最大值；相同间隙时，台阶斜齿的封严效果最好，其流量系数比基准常规齿时小40%左右。直通针型齿、直通宝塔齿的封严效果略优于基准常规齿，三者相差不大；但是，泄漏流量越小，级间封严的温升和旋流越大。压比1.30时台阶斜齿与基准常规齿的温升比为1.5左右。另外，高转速时台阶斜齿比基准常规齿的旋转比大18%左右。

Abstract:

To compare the performances of compressor inter-stage seal for different tooth shapes， the experiments were conducted at an inter-stage seal test facility for conventional straight-through， needlelike， tower-type and stepped and slanted labyrinth seals. Working tip clearances， leakage flow rates， windage heating and swirl ratios in the outlet cavity were measured at different pressure ratios (1.05～1.30) and different rotating speeds (0～8.1kr/min). The leakage behavior， windage heating characteristic and swirl characteristic of three new tooth shapes were compared with conventional straight-through labyrinth seal (the most used) in the current study. Results show that very small as well as very large tip clearances yield lower discharge coefficient [CD] values than medium clearances with a maximum around 0.8mm for conventional straight-through labyrinth seal. The stepped and slanted labyrinth seal has the best sealing capability and reduces discharge coefficient as much as 40% compared to conventional straight-through labyrinth seal. In addition， discharge coefficients of needlelike and tower-type straight-through labyrinth seals are slightly lower than the [CD]-values of conventional one. However， the reduction of leakage flow through the stator well leads to increases in the temperature rise and swirl velocity. The ratios of temperature rises between the stepped and slanted labyrinth seal and conventional straight-through labyrinth seal are around 1.5 at pessure ratio of 1.30. For high rotational speeds， the swirl ratios of stepped and slanted labyrinth seal are found 18% larger than that of conventional straight-through labyrinth seal.