刷式-迷宫密封泄漏流动和转子动力特性数值研究
|
摘要
为评估刷式-迷宫密封的封严性能和偏心涡动时对转子安全稳定性的影响,采用基于涡动转子法和非线性Darcian多孔介质模型,建立了数值研究刷式-迷宫密封泄漏流动和转子动力特性的数学模型。研究了压比为1.96、3、4.49、6.9,进口预旋速度为-50、-30、0、30、50 m/s和4种转子自旋速度为3×10~3、7.5×10~3、1.5×10~4、2×10~4 r/min下刷式-迷宫密封泄漏流动特性和转子动力特性系数,并与传统迷宫密封进行了比较。研究结果表明:刷式-迷宫密封的泄漏量显著小于迷宫密封,在压比为6.9时,刷式-迷宫密封的有效间隙仅为迷宫密封的25.5%;刷式-迷宫密封的直接刚度随压比和进口预旋速度绝对值增大而增大,随转子自旋速度改变变化不明显;有效阻尼随进口预旋和转子自旋速度的升高而降低。刷丝束具有止旋作用,相比迷宫密封,刷式-迷宫密封的交叉刚度和有效阻尼对运行工况变化敏感度更低,且刷式-迷宫密封的直接刚度在研究工况范围内均大于迷宫密封,临界转速更高。在相同工况条件下,刷式-迷宫密封的封严性能显著优于迷宫密封,正向预旋速度较大或转子自旋速度较低时,刷式-迷宫密封有效阻尼大于迷宫密封,转子系统的稳定性更好。
To evaluate the sealing performance of brush-labyrinth seal and the effect on the rotor stability under eccentric whirl condition, a numerical method for investigating the leakage and rotordynamic characteristics of brush-labyrinth seal was presented based on the whirling rotor method and nonlinear Darcian porous medium model. The leakage flow characteristics and rotordynamic coefficients of brush-labyrinth seal under different working conditions including four pressure ratios(1.96, 3, 4.49, 6.9), five inlet preswirl velocities(-50,-30, 0, 30, 50 m/s) and four rotor spinning speeds(3×10~3、7.5×10~3、1.5×10~4、2×10~4 r/min) were studied. The influences of pressure ratio, inlet preswirl velocity and spinning speed on the brush-labyrinth seal leakage and rotordynamic characteristics were studied. The leakage and rotordynamic coefficients of brush-labyrinth seal were compared with the numerical results of traditional labyrinth seal. The results show that the leakage rate of brush-labyrinth seal is significantly lower than that of labyrinth seal. The effective clearance of the brush-labyrinth seal is only 25.5% of that in labyrinth seal when the pressure ratio is 6.9. The direct stiffness of the brush-labyrinth seal increases with the pressure ratio and the absolute value of the inlet preswirl, and does not change significantly with the change of the rotor spinning speed. The effective damping decreases with the increase of the inlet preswirl and the rotor spinning speed, and the bristle pack can act as a swirl brake. Compared with labyrinth seal, the cross-coupled stiffness and effective damping of brush-labyrinth seal are insensitive to changes of operation conditions and the direct stiffness of the brush-labyrinth seal is large in the whole studied working conditions, so the critical speed is higher. The sealing performance of brush-labyrinth seal is superior to that of labyrinth seal and the effective damping of brush-labyrinth is relatively high at high positive preswirl velocity or low rotor spinning speed, so the rotor system is more stable.
To evaluate the sealing performance of brush-labyrinth seal and the effect on the rotor stability under eccentric whirl condition, a numerical method for investigating the leakage and rotordynamic characteristics of brush-labyrinth seal was presented based on the whirling rotor method and nonlinear Darcian porous medium model. The leakage flow characteristics and rotordynamic coefficients of brush-labyrinth seal under different working conditions including four pressure ratios(1.96, 3, 4.49, 6.9), five inlet preswirl velocities(-50,-30, 0, 30, 50 m/s) and four rotor spinning speeds(3×10~3、7.5×10~3、1.5×10~4、2×10~4 r/min) were studied. The influences of pressure ratio, inlet preswirl velocity and spinning speed on the brush-labyrinth seal leakage and rotordynamic characteristics were studied. The leakage and rotordynamic coefficients of brush-labyrinth seal were compared with the numerical results of traditional labyrinth seal. The results show that the leakage rate of brush-labyrinth seal is significantly lower than that of labyrinth seal. The effective clearance of the brush-labyrinth seal is only 25.5% of that in labyrinth seal when the pressure ratio is 6.9. The direct stiffness of the brush-labyrinth seal increases with the pressure ratio and the absolute value of the inlet preswirl, and does not change significantly with the change of the rotor spinning speed. The effective damping decreases with the increase of the inlet preswirl and the rotor spinning speed, and the bristle pack can act as a swirl brake. Compared with labyrinth seal, the cross-coupled stiffness and effective damping of brush-labyrinth seal are insensitive to changes of operation conditions and the direct stiffness of the brush-labyrinth seal is large in the whole studied working conditions, so the critical speed is higher. The sealing performance of brush-labyrinth seal is superior to that of labyrinth seal and the effective damping of brush-labyrinth is relatively high at high positive preswirl velocity or low rotor spinning speed, so the rotor system is more stable.
引文
[1]CHUPP R E,HENDRICKS R C,LATTIME S B,et al.Sealing in turbomachinery[J].Journal of Propulsion and Power,2006,22(2):313-349.
[2]PUGACHEV A O,DECKNER M.CFD prediction and test results of stiffness and damping coefficients for brush-labyrinth gas seals[C]∥ASME Turbo Expo2010:Power for Land,Sea,and Air.New York,USA:ASME,2010:GT2010-22667.
[3]SCHUR F,FRIEDRICHS J,FLEGLER J,et al.Pressure distributions below brush seals at varying operating conditions[C]∥ASME Turbo Expo 2018:Turbomachinery Technical Conference and Exposition.New York,USA:ASME,2018:GT2018-76194.
[4]LI Jun,QIU Bo,FENG Zhenping.Experimental and numerical investigations on the leakage flow characteristics of the labyrinth brush seal[J].ASME Journal of Engineering for Gas Turbines and Power,2012,134(10):102509.
[5]DOGU Y,BAHAR A S,SERTCAKAN M C,et al.Computational fluid dynamics investigation of brush seal leakage performance depending on geometric dimensions and operating conditions[J].Journal of Engineering for Gas Turbines and Power,2016,138(3):032506.
[6]CONNER K J,CHILDS D W.Rotordynamic coefficient test results for a four-stage brush seal[J].Journal of Propulsion and Power,1993,9(3):462-465.
[7]LAOS H E,VANCE J M,BUCHANAN S E.Hybrid brush pocket damper seals for turbomachinery[J].ASME Journal of Engineering for Gas Turbines and Power,2000,122(2):330-336.
[8]PUGACH A O,DECKNER M.Experimental and theoretical rotordynamic stiffness coefficients for a three-stage brush seal[J].Mechanical Systems&Signal Processing,2012,31:143-154.
[9]GASZNER M,PUGACHEV A O,GEORGAKIS C,et al.Leakage and rotordynamic coefficients of brush seals with zero cold clearance used in an arrangement with labyrinth fins[J].ASME Journal of Engineering for Gas Turbines and Power,2013,135(12):122506.
[10]YUAN Wei,DOWELL E H,CHEN Zhaobo,et al.Influence of geometry on rotordynamic coefficients of brush seal[J].International Journal of Turbo&JetEngines,2017,34(2):155-166.
[11]陈尧兴,李志刚,李军.非均匀进汽时迷宫密封汽流激振动力特性的研究[J].西安交通大学学报,2017,51(9):145-152.CHEN Yaoxing,LI Zhigang,LI Jun.Fluid excited rotordynamic characteristics of labyrinth seal during non-uniform inlet flowing[J].Journal of Xi’an Jiaotong University,2017,51(9):145-152.
[12]李志刚,陈尧兴,李军.高偏心下旋转密封泄漏特性和静态动力特性研究[J].西安交通大学学报,2017,51(7):1-7.LI Zhigang,CHEN Yaoxing,LI Jun.Investigation on the leakage and static dynamic characteristics of rotating seals at high eccentricity ratios[J].Journal of Xi’an Jiaotong University,2017,51(7):1-7.
[13]PUGACHEV A O.Aggregation of experimental and theoretical data for brush seal leakage evaluation[C]∥50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference:Propulsion and Energy Forum.Reston,VA,USA:AIAA,2014:AIAA-2014-3598.
[14]HIRANO T,GUO Z,KIRK R G.Application of computational fluid dynamics analysis for rotating machinery:part II Labyrinth seal analysis[J].ASMEJournal of Engineering for Gas Turbines and Power,2005,127(4):820-826.
[15]PUGACHEV A O,GRIEBEL C,TIBOS S,et al.Performance analysis of hybrid brush pocket damper seals using computational fluid dynamics[C]∥ASMETurbo Expo 2016:Turbomachinery Technical Conference and Exposition.New York,USA:ASME,2016:GT2016-57418.
[2]PUGACHEV A O,DECKNER M.CFD prediction and test results of stiffness and damping coefficients for brush-labyrinth gas seals[C]∥ASME Turbo Expo2010:Power for Land,Sea,and Air.New York,USA:ASME,2010:GT2010-22667.
[3]SCHUR F,FRIEDRICHS J,FLEGLER J,et al.Pressure distributions below brush seals at varying operating conditions[C]∥ASME Turbo Expo 2018:Turbomachinery Technical Conference and Exposition.New York,USA:ASME,2018:GT2018-76194.
[4]LI Jun,QIU Bo,FENG Zhenping.Experimental and numerical investigations on the leakage flow characteristics of the labyrinth brush seal[J].ASME Journal of Engineering for Gas Turbines and Power,2012,134(10):102509.
[5]DOGU Y,BAHAR A S,SERTCAKAN M C,et al.Computational fluid dynamics investigation of brush seal leakage performance depending on geometric dimensions and operating conditions[J].Journal of Engineering for Gas Turbines and Power,2016,138(3):032506.
[6]CONNER K J,CHILDS D W.Rotordynamic coefficient test results for a four-stage brush seal[J].Journal of Propulsion and Power,1993,9(3):462-465.
[7]LAOS H E,VANCE J M,BUCHANAN S E.Hybrid brush pocket damper seals for turbomachinery[J].ASME Journal of Engineering for Gas Turbines and Power,2000,122(2):330-336.
[8]PUGACH A O,DECKNER M.Experimental and theoretical rotordynamic stiffness coefficients for a three-stage brush seal[J].Mechanical Systems&Signal Processing,2012,31:143-154.
[9]GASZNER M,PUGACHEV A O,GEORGAKIS C,et al.Leakage and rotordynamic coefficients of brush seals with zero cold clearance used in an arrangement with labyrinth fins[J].ASME Journal of Engineering for Gas Turbines and Power,2013,135(12):122506.
[10]YUAN Wei,DOWELL E H,CHEN Zhaobo,et al.Influence of geometry on rotordynamic coefficients of brush seal[J].International Journal of Turbo&JetEngines,2017,34(2):155-166.
[11]陈尧兴,李志刚,李军.非均匀进汽时迷宫密封汽流激振动力特性的研究[J].西安交通大学学报,2017,51(9):145-152.CHEN Yaoxing,LI Zhigang,LI Jun.Fluid excited rotordynamic characteristics of labyrinth seal during non-uniform inlet flowing[J].Journal of Xi’an Jiaotong University,2017,51(9):145-152.
[12]李志刚,陈尧兴,李军.高偏心下旋转密封泄漏特性和静态动力特性研究[J].西安交通大学学报,2017,51(7):1-7.LI Zhigang,CHEN Yaoxing,LI Jun.Investigation on the leakage and static dynamic characteristics of rotating seals at high eccentricity ratios[J].Journal of Xi’an Jiaotong University,2017,51(7):1-7.
[13]PUGACHEV A O.Aggregation of experimental and theoretical data for brush seal leakage evaluation[C]∥50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference:Propulsion and Energy Forum.Reston,VA,USA:AIAA,2014:AIAA-2014-3598.
[14]HIRANO T,GUO Z,KIRK R G.Application of computational fluid dynamics analysis for rotating machinery:part II Labyrinth seal analysis[J].ASMEJournal of Engineering for Gas Turbines and Power,2005,127(4):820-826.
[15]PUGACHEV A O,GRIEBEL C,TIBOS S,et al.Performance analysis of hybrid brush pocket damper seals using computational fluid dynamics[C]∥ASMETurbo Expo 2016:Turbomachinery Technical Conference and Exposition.New York,USA:ASME,2016:GT2016-57418.