600MW汽轮机组主油泵叶轮的“流—固”耦合结构分析
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摘要
主油泵作为汽轮机组供油系统的动力源和核心设备,其流体动力和结构力学性能间接地对汽轮机组的运行安全性和可靠性有非常大的影响。为了满足大型汽轮机组油系统需要,这类主油泵工作压力高达1.4～2.0MPa,叶轮转速高达3000r/min。随着汽轮机组单机容量的不断增加和结构尺寸的巨型化,对汽轮机组的油系统的适应性和可靠性要求越来越高,不仅要求主油泵具有高效率,而且要求流量大和对变工况的适应性强,更要求在结构上紧凑和高可靠性,也相应地对主油泵的设计和可靠性提出了更大的挑战。
600MW汽轮机组是现阶段及未来一段时期内我国火电站和核电站的主力发机型,其油系统广泛采用了“主油泵-油涡轮-升压泵”系统。为了保证性能要求,目前国内大型汽轮机制造厂在大型汽轮机配套的油系统的关键设备(如主油泵、油涡轮、升压泵等)方面一般从国外进口或引进技术生产。本论文的课题结合我国600MW汽轮机主油泵及油涡轮国产化研制的要求,针对国内自主创新开发出600MW级机型配套的主油泵产品需要解决的关键技术之一:在高压流体和高转速工作下的叶轮的结构动力学特性及可靠性方面进行研究。
本文在深入分析主油泵在油系统中的工作状况及内部流场流体动力学模型和结构动力学模型的基础上,为了提高分析的可靠性,首先采用CFD(Computational Fluid Dynamics)软件对主油泵进行的全流道流场数值模拟,计算出作用在叶轮流道表面上的流体压力分布。再将流场数值模拟结果传递给叶轮结构分析,初步实现了采用“流-固”耦合(FSI:Fluid Solid Interaction)结构分析技术对主油泵叶轮进行结构静力学分析和转子动力学分析。为了分析叶轮在空气中和正常工作状态的力学特性差异,分别对于叶轮在空气和透平油两种工作介质中的结构力学性能进行了计算。考虑到工程实际情况,除对叶轮在正常转速条件下进行计算,还分别对于两种工作介质进行超速120%的工况行了计算分析。通过对这些工况的计算分析,掌握了主油泵叶轮结构的各项力学性能,如刚度、强度以及模态特性、自振频率等。根据计算结果,验证了该部件的工作可靠性,为保证主油泵在实际工作中能够安全运行提供了依据,为600MW汽轮机组主油泵的结构优化和新型主油泵的开发奠定了理论和技术基础。
本文结合600MW汽轮机组主油泵结构优化的工程实际要求,应用“流-固”耦合结构分析技术对于在高压流体和高转速条件下工作的低比转速双吸离心主油泵叶轮进行结构动力学特性分析,解决了工程实际问题。并证明将“流-固”耦合仿真分析技术应用于主油泵设计分析比不考虑流体作用的预测分析的精度高,这不仅有利于保证产品的可靠性,而且可以缩短研制周期,降低开发成本。研究成果已用于大型汽轮机组配套的主油泵国产化和国内自主创新研究开发中,其方法可以进一步推广应用的其它叶片式流体机械,对叶片式流体机械的数字化设计理论和方法的发展等都有重要意义。
Main oil pump is power source and key equipment of oil supply system of steam turbine unit. Its hydrodynamic properties and structural mechanics properties indirectly have mortal influence on operation safety and reliability of steam turbine unit. According to the needs of oil supply system, working pressure of this kind of main oil pump is up to 1.4～2.0MPa, impeller rotating speed reaches to 3000r/min.With increasing in capacity and structural size of steam turbine unit, adaptability and reliability of oil supply system of steam turbine unit is required higher and higher. Not only needs main oil pump achieving high efficiency, but also requires it to adapt to large flowates and work condition changing, and more compact in structure and higher in reliability. Accordingly, they bring a greater challenge to design and improve reliability for main oil pump.
At present and in future years, 600MW steam turbine unit is widely used type in thermal power station and nuclear power station. Its oil supply system widely adopted "main oil pump-oil turbine-booster pump" system. As so far, for guaranteeing safety of a large scale steam turbine unit, key equipments of oil supply system of a large scale steam turbine unit usually import from abroad or import technology to make in domestic manufacturer. In order to the subject of this paper combined with requirement of self-development of main oil pump and oil turbine in china, one of key technologies to develop domestic independent innovation development main oil pump matching 600MW steam turbine unit has been studied in this thesis, which is structural dynamic characteristics and reliability of impeller in high pressure flow and high rotational speed environment.
According to working condition of main oil pump in oil supply system, internal flow field dynamics model and structural dynamical model of main oil pump were analysed. To ensure reliability of analysis, firstly, commercial CFD software was used to do a numerical simulation for whole flow passage of main oil pump, and to obtain fluid pressure distribution on flow passage surface of impeller; subsequently export numerical simulation results to structural analysis for impeller as load; then, structural static analysis and rotor dynamic analysis have been basically completed by using FSI method. For analyzing difference of mechanical properties of impeller between in air and under normal operation, mechanical properties of impeller in two kinds of medium had been respectively simulated. Considering requirements of actual engineering, structural static analysis and rotor dynamic analysis had been done at condition of 120% working revolution speed for two kinds of medium . Through analyzing these conditions, all kinds of structural mechanics properties of impeller of main oil pump, such as stiffness、strength and modal characteristics,natural frequency and so on have been carried out. According to analysis, reliability and safety of this impeller has been verified. It set up a theory and technology foundation of structural optimization for main oil pump of 600MW steam turbine unit and for developing new type main oil pump also.
Combined with structural optimization of main oil pump of 600MW steam turbine unit based on practical engineering requirements in this thesis , FSI method has been used to make structural dynamic characteristics analysis for impeller of low specific speed-double suction-centrifugal main oil pump from an actual engineering. It is proved that precision with FSI is higher than without FSI in structural analysis of main oil pump, and which is not only beneficial to guarantee reliability of pump, but also shorten research cycle and decrease R&D cost. This research has been applied to design of main oil pump by domestic independent innovation and development. This method may be further extended to other kind of turbo machinery, and which has important significance on theory and method of digital design of fluid machinery.
600MW汽轮机组是现阶段及未来一段时期内我国火电站和核电站的主力发机型,其油系统广泛采用了“主油泵-油涡轮-升压泵”系统。为了保证性能要求,目前国内大型汽轮机制造厂在大型汽轮机配套的油系统的关键设备(如主油泵、油涡轮、升压泵等)方面一般从国外进口或引进技术生产。本论文的课题结合我国600MW汽轮机主油泵及油涡轮国产化研制的要求,针对国内自主创新开发出600MW级机型配套的主油泵产品需要解决的关键技术之一:在高压流体和高转速工作下的叶轮的结构动力学特性及可靠性方面进行研究。
本文在深入分析主油泵在油系统中的工作状况及内部流场流体动力学模型和结构动力学模型的基础上,为了提高分析的可靠性,首先采用CFD(Computational Fluid Dynamics)软件对主油泵进行的全流道流场数值模拟,计算出作用在叶轮流道表面上的流体压力分布。再将流场数值模拟结果传递给叶轮结构分析,初步实现了采用“流-固”耦合(FSI:Fluid Solid Interaction)结构分析技术对主油泵叶轮进行结构静力学分析和转子动力学分析。为了分析叶轮在空气中和正常工作状态的力学特性差异,分别对于叶轮在空气和透平油两种工作介质中的结构力学性能进行了计算。考虑到工程实际情况,除对叶轮在正常转速条件下进行计算,还分别对于两种工作介质进行超速120%的工况行了计算分析。通过对这些工况的计算分析,掌握了主油泵叶轮结构的各项力学性能,如刚度、强度以及模态特性、自振频率等。根据计算结果,验证了该部件的工作可靠性,为保证主油泵在实际工作中能够安全运行提供了依据,为600MW汽轮机组主油泵的结构优化和新型主油泵的开发奠定了理论和技术基础。
本文结合600MW汽轮机组主油泵结构优化的工程实际要求,应用“流-固”耦合结构分析技术对于在高压流体和高转速条件下工作的低比转速双吸离心主油泵叶轮进行结构动力学特性分析,解决了工程实际问题。并证明将“流-固”耦合仿真分析技术应用于主油泵设计分析比不考虑流体作用的预测分析的精度高,这不仅有利于保证产品的可靠性,而且可以缩短研制周期,降低开发成本。研究成果已用于大型汽轮机组配套的主油泵国产化和国内自主创新研究开发中,其方法可以进一步推广应用的其它叶片式流体机械,对叶片式流体机械的数字化设计理论和方法的发展等都有重要意义。
Main oil pump is power source and key equipment of oil supply system of steam turbine unit. Its hydrodynamic properties and structural mechanics properties indirectly have mortal influence on operation safety and reliability of steam turbine unit. According to the needs of oil supply system, working pressure of this kind of main oil pump is up to 1.4～2.0MPa, impeller rotating speed reaches to 3000r/min.With increasing in capacity and structural size of steam turbine unit, adaptability and reliability of oil supply system of steam turbine unit is required higher and higher. Not only needs main oil pump achieving high efficiency, but also requires it to adapt to large flowates and work condition changing, and more compact in structure and higher in reliability. Accordingly, they bring a greater challenge to design and improve reliability for main oil pump.
At present and in future years, 600MW steam turbine unit is widely used type in thermal power station and nuclear power station. Its oil supply system widely adopted "main oil pump-oil turbine-booster pump" system. As so far, for guaranteeing safety of a large scale steam turbine unit, key equipments of oil supply system of a large scale steam turbine unit usually import from abroad or import technology to make in domestic manufacturer. In order to the subject of this paper combined with requirement of self-development of main oil pump and oil turbine in china, one of key technologies to develop domestic independent innovation development main oil pump matching 600MW steam turbine unit has been studied in this thesis, which is structural dynamic characteristics and reliability of impeller in high pressure flow and high rotational speed environment.
According to working condition of main oil pump in oil supply system, internal flow field dynamics model and structural dynamical model of main oil pump were analysed. To ensure reliability of analysis, firstly, commercial CFD software was used to do a numerical simulation for whole flow passage of main oil pump, and to obtain fluid pressure distribution on flow passage surface of impeller; subsequently export numerical simulation results to structural analysis for impeller as load; then, structural static analysis and rotor dynamic analysis have been basically completed by using FSI method. For analyzing difference of mechanical properties of impeller between in air and under normal operation, mechanical properties of impeller in two kinds of medium had been respectively simulated. Considering requirements of actual engineering, structural static analysis and rotor dynamic analysis had been done at condition of 120% working revolution speed for two kinds of medium . Through analyzing these conditions, all kinds of structural mechanics properties of impeller of main oil pump, such as stiffness、strength and modal characteristics,natural frequency and so on have been carried out. According to analysis, reliability and safety of this impeller has been verified. It set up a theory and technology foundation of structural optimization for main oil pump of 600MW steam turbine unit and for developing new type main oil pump also.
Combined with structural optimization of main oil pump of 600MW steam turbine unit based on practical engineering requirements in this thesis , FSI method has been used to make structural dynamic characteristics analysis for impeller of low specific speed-double suction-centrifugal main oil pump from an actual engineering. It is proved that precision with FSI is higher than without FSI in structural analysis of main oil pump, and which is not only beneficial to guarantee reliability of pump, but also shorten research cycle and decrease R&D cost. This research has been applied to design of main oil pump by domestic independent innovation and development. This method may be further extended to other kind of turbo machinery, and which has important significance on theory and method of digital design of fluid machinery.
引文