平衡鼓间隙对首级叶轮前泵腔压力及多级泵轴向力的影响
|
摘要
平衡鼓的轴向力平衡能力是多级离心泵发生故障并影响其寿命的关键因素。该文采用数值模拟方法,在多级泵的外特性、平衡管内压力和泄漏量的数值计算结果与试验结果基本一致的基础上,研究了平衡鼓间隙泄漏量变化对首级叶轮前泵腔的压力分布、首级叶轮及整个叶轮轴向力的影响。研究结果表明:首级叶轮前泵腔中的漩涡区是腔体内压力变化的主要原因。当平衡鼓间隙由0增大到0.5 mm时,首级叶轮的轴向力在间隙为0时最大,在间隙为0.3 mm时最小,其最小值为最大值的20.6%;整个叶轮所受轴向力随着平衡鼓间隙增大呈先减小后增大的趋势。无量纲化的平衡鼓间隙面积大于6.6×10-3时,由于平衡鼓前后压差较小,已无法有效平衡轴向力,在此范围轴承发生断轴的风险较大。该研究可为多级泵平衡鼓设计提供参考。
The ability of the balance drum to balance the axial force is the key factor for the failure of multistage centrifugal pump. However, during the operation of the balance drum, due to the long-term collision with the liquid or the friction with the casing, the leakage amount at the balance drum clearance is gradually increased, resulting in the balance drum being worn. Therefore, studying the leakage flow is critical to the ability of the balance drum to accurately balance the axial force of the entire impeller. In this paper, three-dimensional turbulent flow of multistage centrifugal pump was simulated by using the CFD code FLUENT. Besides, steady simulation was conducted for different operating points of the pump, the turbulence was simulated with shear stress transportation(SST) turbulence model together with automatic near wall treatment. CFD results were compared with those from the model test. And the results of the pressure and leakage in the balance pipe and the external characteristics of the multistage pump were basically consistent with the experimental results. Moreover, the maximum errors of head, efficiency and shaft power were 4.17%, 2.81% and 4.25% respectively, but the experimental flow rate of balance pipe was always greater than the simulated one. This was mainly because the influence of orifice flowmeter in the pipe had been not taken into account in the numerical simulation. The maximum error of the flow rate of the balanced pipe at the design point was 4.49%. The maximum error of pressure was 2.5%. It showed that the calculation method selected in this paper could provide a reliable guarantee for this study. The results showed that at the design flow rate, the liquid pressure in the front cavity of the first impeller increased gradually along the axial direction from the inlet section to the outlet section. When the balance drum clearance was less than 0.2 mm, the pressure distribution along the radial direction was uniform in each section. But when the clearance was more than 0.2 mm, it was asymmetric. Furthermore, with the increase of clearance, the pressure inhomogeneity became more obvious. Moreover, at 0.5 Q(Q is design flow, Q=128 m3/h) and 1.5 Q flow rates, there was no obvious regularity of pressure increment along the radial direction under different clearances. The pressure increment was the smallest when the balance drum clearance was 0.3 mm, and the biggest when the balance drum clearance was 0. And under the above 2 conditions, the minimum increments were 50.7% and 88.9% of the maximum, respectively. When the clearance increased from 0 to 0.5 mm, under design flow rate, the pressure increased gradually along the radial direction. Wherein, when the clearance was 0 and 0.5 mm, the pressure increment was the maximum value and the minimum value, respectively, and the minimum value was 44.6% of the maximum value. Besides, there was a large vortex region in the front cavity of the first impeller, when the clearance of balance drums was 0, 0.3 and 0.5 mm, respectively. The vortex region decreased gradually with the increase of flow rate, which indicated that the appearance of the vortex region was the main reason for the change of pressure in the cavity. In addition, with the increase of clearance, the total axial force of 11 stage impellers decreased first and then increased. And when non-dimensionalized balance drum clearance area was greater than 6.6×10-3, the balance drum could not effectively balance the axial force. Furthermore, the bearing had a greater risk of fracture in this range. This research can provide useful reference for design of balance drum and prediction of risk of bearing fracture.
The ability of the balance drum to balance the axial force is the key factor for the failure of multistage centrifugal pump. However, during the operation of the balance drum, due to the long-term collision with the liquid or the friction with the casing, the leakage amount at the balance drum clearance is gradually increased, resulting in the balance drum being worn. Therefore, studying the leakage flow is critical to the ability of the balance drum to accurately balance the axial force of the entire impeller. In this paper, three-dimensional turbulent flow of multistage centrifugal pump was simulated by using the CFD code FLUENT. Besides, steady simulation was conducted for different operating points of the pump, the turbulence was simulated with shear stress transportation(SST) turbulence model together with automatic near wall treatment. CFD results were compared with those from the model test. And the results of the pressure and leakage in the balance pipe and the external characteristics of the multistage pump were basically consistent with the experimental results. Moreover, the maximum errors of head, efficiency and shaft power were 4.17%, 2.81% and 4.25% respectively, but the experimental flow rate of balance pipe was always greater than the simulated one. This was mainly because the influence of orifice flowmeter in the pipe had been not taken into account in the numerical simulation. The maximum error of the flow rate of the balanced pipe at the design point was 4.49%. The maximum error of pressure was 2.5%. It showed that the calculation method selected in this paper could provide a reliable guarantee for this study. The results showed that at the design flow rate, the liquid pressure in the front cavity of the first impeller increased gradually along the axial direction from the inlet section to the outlet section. When the balance drum clearance was less than 0.2 mm, the pressure distribution along the radial direction was uniform in each section. But when the clearance was more than 0.2 mm, it was asymmetric. Furthermore, with the increase of clearance, the pressure inhomogeneity became more obvious. Moreover, at 0.5 Q(Q is design flow, Q=128 m3/h) and 1.5 Q flow rates, there was no obvious regularity of pressure increment along the radial direction under different clearances. The pressure increment was the smallest when the balance drum clearance was 0.3 mm, and the biggest when the balance drum clearance was 0. And under the above 2 conditions, the minimum increments were 50.7% and 88.9% of the maximum, respectively. When the clearance increased from 0 to 0.5 mm, under design flow rate, the pressure increased gradually along the radial direction. Wherein, when the clearance was 0 and 0.5 mm, the pressure increment was the maximum value and the minimum value, respectively, and the minimum value was 44.6% of the maximum value. Besides, there was a large vortex region in the front cavity of the first impeller, when the clearance of balance drums was 0, 0.3 and 0.5 mm, respectively. The vortex region decreased gradually with the increase of flow rate, which indicated that the appearance of the vortex region was the main reason for the change of pressure in the cavity. In addition, with the increase of clearance, the total axial force of 11 stage impellers decreased first and then increased. And when non-dimensionalized balance drum clearance area was greater than 6.6×10-3, the balance drum could not effectively balance the axial force. Furthermore, the bearing had a greater risk of fracture in this range. This research can provide useful reference for design of balance drum and prediction of risk of bearing fracture.
引文
[1]关醒凡.现代泵理论与设计[M].北京:中国宇航出版社,2011:498-530.
[2]金建波.平衡鼓平衡轴向力方法的研究与探讨[D].杭州:浙江工业大学,2010.Jin Jianbo.Study and Investigation on the Axial Force Balance Method by Balance Drum[D].Hangzhou:Zhejiang University of Technology,2012.(in Chinese with English abstract)
[3]Johann Friedrich Gülich.Centrifugal Pumps[M].Switzerland:Springer-Verlag Berlin Heidelberg 2008,2010:544-545.
[4]刘在伦,董玮,张楠,等.离心泵平衡腔液体压力的计算与验证[J].农业工程学报,2013,29(20):54-59.Liu Zailun,Dong Wei,Zhang Nan,et al.Calculation and validation of fluid pressure of balance cavity in Centrifugal Pump[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2013,29(20):54-59.(in Chinese with English abstract)
[5]董玮,楚武利.离心泵叶轮平衡腔内液体流动特性及圆盘损失分析[J].农业机械学报,2016,47(7):29-35.Dong Wei,Chu Wuli.Analysis of flow Characteristics and disc friction loss in balance cavity of centrifugal pump impeller[J].Transactions of the Chinese Society for Agricultural Machinery,2016,47(7):29-35.(in Chinese with English abstract)
[6]Dong Wei,Chu Wuli.Numerical investigation of the fluid flow characteristic in the hub plate crown of a centrifugal pump[J].Chinese Journal of Mechanical Engineering,2018,31(1):64.
[7]Dong Wei,Chu Wuli.Numerical investigation of fluid flow mechanism in the back shroud cavity of a centrifugal pump[J]Journal of Applied Fluid Mechanics,2018,11(3):709-719.
[8]董玮,楚武利.离心泵后泵腔内液体压力数值分析与验证[J].机械工程学报,2016,52(4):165-170.Dong Wei,Chu Wuli.Numerical analysis and validation of fluid pressure in the back chamber of centrifugal pump[J].Journal of Mechanical Engineering,2016,52(4):165-170.(in Chinese with English abstract)
[9]Gordon Kirk,Rui Gao.Influence of preswirl on rotordynamic characteristics of labyrinth seals[J].Tribology Transactions,2012,55:357-364.
[10]Rui Gao,Gordon Kirk.CFD study on stepped and drum balance labyrinth seal[J].Tribology Transactions,2013,56:663-671.
[11]张贤安,金建波.平衡鼓间隙尺寸对多级泵轴向平衡能力影响的分析[J].流体机械,2013(41):49-53.Zhang Xianan,Jin Jianbo.Analysis on the influence of balance drum gap sizes on axial balanced capacity in multistage pumps[J].Fluid Machinery,2013(41):49-53.(in Chinese with English abstract)
[12]林玲.平衡鼓间隙对离心泵轴向力平衡的影响[J].轻工机械,2013(6):13-16.Lin Ling.Effect of balance drum clearance on axial force balance of multistage centrifugal pumps[J].Light Industry Machinery,2013(6):13-16.(in Chinese with English abstract)
[13]张翼飞,杨从新.平衡鼓直径的实验确定法[J].水泵技术,1996(5):24-27.Zhang Yifei,Yang Congxin.Method for determining balanced diameter of multistage pump[J].Pump Technology,1996(5):24-27.(in Chinese with English abstract)
[14]欧阳武,袁小阳,宋建军,等.平衡鼓和平衡盘的系统模型及应用[J].机械科学与技术,2012,31(11):1731-1734.Ouyang Wu,Yuan Xiaoyang,Song Jianjun,et al.System modeland application of balancing drum and balancing disc[J].Mechanical Science and Technology for Aerospace Engineering,2012,31(11):1731-1734.(in Chinese with English abstract)
[15]汪建华,戴静君.平衡鼓和平衡盘联合结构的优化设计[J].汉江石油学院学报,2000,22(2):52-54.Wang Jianhua,Dai Jingjun.Optimum design of the joint structure of balance drum and balance disk[J].Journal of Hanjiang Petroleum Institute,2000,22(2):52-54.(in Chinese with English abstract)
[16]汪建华,周志宏,赵子传.注水泵双平衡鼓装置的优化设计[J].石油机械,2000,28(8):8-11.Wang Jianhua,Zhou Zhihong,Zhao Zizhuan.Optimum design of double balance drum device for water injection pump[J].Petroleum Machinery,2000,28(8):8-11.(in Chinese with English abstract)
[17]陆河权,牟介刚,郑水华,等.凹槽深度对新型平衡鼓性能影响的研究[J].浙江工业大学学报,2012,40(5):559-566.Lu Hequan,Mu Jiegang,Zheng Shuihua,et al.Study on the influence of the depth of groove on the performance of novel balance drum[J].Journal of Zhejiang University of Technology,2012,40(5):559-566.(in Chinese with English abstract)
[18]陈云富.离心泵泵腔内压力分布规律的研究[D].兰州:兰州理工大学,2005.Chen Yunfu.The Research of Pressure Distribution Rule in the Chamber of Centrifugal Pump[D].Lanzhou:Lanzhou University of Technology,2005.(in Chinese with English abstract)
[19]张春晋,孙西欢,李永业,等.螺旋流起旋器内部流场水力特性数值模拟与验证[J].农业工程学报,2018,34(1):53-62.Zhang Chunjin,Sun Xihuan,Li Yongye,et al.Numerical simulation and verification of hydraulic characteristics of internal flow filed in spiral flow generator[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2018,34(1):53-62.(in Chinese with English abstract)
[20]李伟,季磊磊,施卫东,等.基于Hilbert-Huang变换的混流泵流动诱导振动试验[J].农业工程学报,2018,34(2):47-54.Li Wei,Ji Leilei,Shi Weidong,et al.Experiment of flow induced vibration of mixed-flow pump based on Hilbert-Huang transform[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2018,34(2):47-54.(in Chinese with English abstract)
[21]李伟,施卫东,蒋小平,等.多级离心泵轴向力的数值计算与试验研究[J].农业工程学报,2012,28(23):52-59.Li Wei,Shi Weidong,Jiang Xiaoping,et al.Numerical calculation and experimental study of axial force on multistage centrifugal pump[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2012,28(23):52-59.(in Chinese with English abstract)
[22]Cao Weidong,Dai Xun,Hu Qixiang.Effect of impeller reflux balance holes on pressure and axial force of centrifugal pump[J].Journal of Central South University,2015,22:1695-1706.
[23]Wang Chuan,Shi Weidong,Li Zhang.Calculation formula optimization and effect of ring clearance on axial force of multistage pump[J].Mathematical Problems in Engineering.DOI:10.1155/2013/749375.
[24]Zhou L,Shi W,Li W,et al.Numerical and experimental study of axial force and hydraulic performance in a deep-well centrifugal pump with different impeller rear shroud radius[J].Journal of Fluid Engineering,2013,135(10):104501-1-104501-8.
[25]Bj?rnW,Friedrich B,Hans D.Investigation of the flow in the impeller side clearances of a centrifugal pump with volute casing[J].Journal of Thermal Science,2012,2(3):197-208.
[26]Yogesh J.Shear and preeure driven flow and thermal transport in microchannels[C]//Proceedings of the Sixth International ASME Conference on Nanochannels,Microchannels and Minichannels(ICNMM2008).Darmstadt,Germany,2008:1677-1688.
[2]金建波.平衡鼓平衡轴向力方法的研究与探讨[D].杭州:浙江工业大学,2010.Jin Jianbo.Study and Investigation on the Axial Force Balance Method by Balance Drum[D].Hangzhou:Zhejiang University of Technology,2012.(in Chinese with English abstract)
[3]Johann Friedrich Gülich.Centrifugal Pumps[M].Switzerland:Springer-Verlag Berlin Heidelberg 2008,2010:544-545.
[4]刘在伦,董玮,张楠,等.离心泵平衡腔液体压力的计算与验证[J].农业工程学报,2013,29(20):54-59.Liu Zailun,Dong Wei,Zhang Nan,et al.Calculation and validation of fluid pressure of balance cavity in Centrifugal Pump[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2013,29(20):54-59.(in Chinese with English abstract)
[5]董玮,楚武利.离心泵叶轮平衡腔内液体流动特性及圆盘损失分析[J].农业机械学报,2016,47(7):29-35.Dong Wei,Chu Wuli.Analysis of flow Characteristics and disc friction loss in balance cavity of centrifugal pump impeller[J].Transactions of the Chinese Society for Agricultural Machinery,2016,47(7):29-35.(in Chinese with English abstract)
[6]Dong Wei,Chu Wuli.Numerical investigation of the fluid flow characteristic in the hub plate crown of a centrifugal pump[J].Chinese Journal of Mechanical Engineering,2018,31(1):64.
[7]Dong Wei,Chu Wuli.Numerical investigation of fluid flow mechanism in the back shroud cavity of a centrifugal pump[J]Journal of Applied Fluid Mechanics,2018,11(3):709-719.
[8]董玮,楚武利.离心泵后泵腔内液体压力数值分析与验证[J].机械工程学报,2016,52(4):165-170.Dong Wei,Chu Wuli.Numerical analysis and validation of fluid pressure in the back chamber of centrifugal pump[J].Journal of Mechanical Engineering,2016,52(4):165-170.(in Chinese with English abstract)
[9]Gordon Kirk,Rui Gao.Influence of preswirl on rotordynamic characteristics of labyrinth seals[J].Tribology Transactions,2012,55:357-364.
[10]Rui Gao,Gordon Kirk.CFD study on stepped and drum balance labyrinth seal[J].Tribology Transactions,2013,56:663-671.
[11]张贤安,金建波.平衡鼓间隙尺寸对多级泵轴向平衡能力影响的分析[J].流体机械,2013(41):49-53.Zhang Xianan,Jin Jianbo.Analysis on the influence of balance drum gap sizes on axial balanced capacity in multistage pumps[J].Fluid Machinery,2013(41):49-53.(in Chinese with English abstract)
[12]林玲.平衡鼓间隙对离心泵轴向力平衡的影响[J].轻工机械,2013(6):13-16.Lin Ling.Effect of balance drum clearance on axial force balance of multistage centrifugal pumps[J].Light Industry Machinery,2013(6):13-16.(in Chinese with English abstract)
[13]张翼飞,杨从新.平衡鼓直径的实验确定法[J].水泵技术,1996(5):24-27.Zhang Yifei,Yang Congxin.Method for determining balanced diameter of multistage pump[J].Pump Technology,1996(5):24-27.(in Chinese with English abstract)
[14]欧阳武,袁小阳,宋建军,等.平衡鼓和平衡盘的系统模型及应用[J].机械科学与技术,2012,31(11):1731-1734.Ouyang Wu,Yuan Xiaoyang,Song Jianjun,et al.System modeland application of balancing drum and balancing disc[J].Mechanical Science and Technology for Aerospace Engineering,2012,31(11):1731-1734.(in Chinese with English abstract)
[15]汪建华,戴静君.平衡鼓和平衡盘联合结构的优化设计[J].汉江石油学院学报,2000,22(2):52-54.Wang Jianhua,Dai Jingjun.Optimum design of the joint structure of balance drum and balance disk[J].Journal of Hanjiang Petroleum Institute,2000,22(2):52-54.(in Chinese with English abstract)
[16]汪建华,周志宏,赵子传.注水泵双平衡鼓装置的优化设计[J].石油机械,2000,28(8):8-11.Wang Jianhua,Zhou Zhihong,Zhao Zizhuan.Optimum design of double balance drum device for water injection pump[J].Petroleum Machinery,2000,28(8):8-11.(in Chinese with English abstract)
[17]陆河权,牟介刚,郑水华,等.凹槽深度对新型平衡鼓性能影响的研究[J].浙江工业大学学报,2012,40(5):559-566.Lu Hequan,Mu Jiegang,Zheng Shuihua,et al.Study on the influence of the depth of groove on the performance of novel balance drum[J].Journal of Zhejiang University of Technology,2012,40(5):559-566.(in Chinese with English abstract)
[18]陈云富.离心泵泵腔内压力分布规律的研究[D].兰州:兰州理工大学,2005.Chen Yunfu.The Research of Pressure Distribution Rule in the Chamber of Centrifugal Pump[D].Lanzhou:Lanzhou University of Technology,2005.(in Chinese with English abstract)
[19]张春晋,孙西欢,李永业,等.螺旋流起旋器内部流场水力特性数值模拟与验证[J].农业工程学报,2018,34(1):53-62.Zhang Chunjin,Sun Xihuan,Li Yongye,et al.Numerical simulation and verification of hydraulic characteristics of internal flow filed in spiral flow generator[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2018,34(1):53-62.(in Chinese with English abstract)
[20]李伟,季磊磊,施卫东,等.基于Hilbert-Huang变换的混流泵流动诱导振动试验[J].农业工程学报,2018,34(2):47-54.Li Wei,Ji Leilei,Shi Weidong,et al.Experiment of flow induced vibration of mixed-flow pump based on Hilbert-Huang transform[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2018,34(2):47-54.(in Chinese with English abstract)
[21]李伟,施卫东,蒋小平,等.多级离心泵轴向力的数值计算与试验研究[J].农业工程学报,2012,28(23):52-59.Li Wei,Shi Weidong,Jiang Xiaoping,et al.Numerical calculation and experimental study of axial force on multistage centrifugal pump[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2012,28(23):52-59.(in Chinese with English abstract)
[22]Cao Weidong,Dai Xun,Hu Qixiang.Effect of impeller reflux balance holes on pressure and axial force of centrifugal pump[J].Journal of Central South University,2015,22:1695-1706.
[23]Wang Chuan,Shi Weidong,Li Zhang.Calculation formula optimization and effect of ring clearance on axial force of multistage pump[J].Mathematical Problems in Engineering.DOI:10.1155/2013/749375.
[24]Zhou L,Shi W,Li W,et al.Numerical and experimental study of axial force and hydraulic performance in a deep-well centrifugal pump with different impeller rear shroud radius[J].Journal of Fluid Engineering,2013,135(10):104501-1-104501-8.
[25]Bj?rnW,Friedrich B,Hans D.Investigation of the flow in the impeller side clearances of a centrifugal pump with volute casing[J].Journal of Thermal Science,2012,2(3):197-208.
[26]Yogesh J.Shear and preeure driven flow and thermal transport in microchannels[C]//Proceedings of the Sixth International ASME Conference on Nanochannels,Microchannels and Minichannels(ICNMM2008).Darmstadt,Germany,2008:1677-1688.