透平膨胀机轴向力数值计算方法研究

发布时间：2018-03-17 06:22

本文选题：透平膨胀机　切入点：轴向力　出处：《兰州理工大学》2014年硕士论文　论文类型：学位论文

【摘要】：透平膨胀机是利用气体的绝热等熵膨胀流动来获得低温和进行能量回收的主要设备。是低温环境模拟、空气分离、天然气液化、氢、氦液化等装置中的关键部件,是保证装置稳定运行的心脏设备。随着工业经济的高速发展,对透平膨胀机提出了高速化、大型化的要求。导致透平膨胀机因轴向力过大出现叶轮轴向窜动等故障。因此,通过研究透平膨胀机轴向力,提高轴向力计算精度和轴系运转的稳定性以及机组可靠性,对透平膨胀机理论设计、工程应用以及延长设备使用寿命都具有重要意义。本文应用计算流体动力学软件FLUNET,以某一透平膨胀机转子系统为研究对象对其轴向力进行了研究和数值模拟。分析了透平膨胀机轴向推力,建立了力学分析模型和叶轮间隙及迷密封的整体三维模型。采用FLUNET软件中的低Re数k-ε模型和SIMPLEC算法,考虑泄漏、气体的可压缩性和粘性的影响,对透平膨胀机轴向推力进行了模拟计算。数值模拟了由于机械磨损导致密封间隙增大情况下轴向力和间隙泄漏量的变化趋势,数值计算结果显示随着密封齿与转子的间隙增大,叶轮间隙侧轴向力逐步减小,间隙的泄漏量随着间隙的增大而增大。验证了网格的无关性,并将数值模拟结果与理论公式计算结果进行了分析比较,找出了造成两者之间差异的原因。分析了叶轮间隙侧不同密封腔时透平膨胀机轴向推力的变化,求解出叶轮侧的压力分布、速度沿轴向分布和间隙泄漏量大小,对不同密封腔时叶轮间隙侧轴向力的大小进行了比较分析。研究了在直齿密封时透平膨胀机轴向力的变化,并对比分析了直齿密封和斜齿密封时叶轮间隙侧泄漏量和轴向力。分析了造成差异的原因,为透平膨胀机提高机组效率和增加机组稳定性提供了方向。
[Abstract]:Turbine expander is the main equipment for obtaining low temperature and energy recovery by using adiabatic isentropic expansion flow of gas. It is a key component in low temperature environment simulation, air separation, natural gas liquefaction, hydrogen, helium liquefaction and so on. With the rapid development of industrial economy, the requirements of high speed and large scale turbine expander are put forward, which lead to the axial movement of impeller due to the excessive axial force of turbine expander and so on. Through the study of axial force of turbine expander, it is of great significance to improve the accuracy of axial force calculation, the stability of shafting operation and the reliability of unit. It is of great significance for the theoretical design, engineering application and prolongation of service life of turbine expander. In this paper, the axial force of a turbine expander rotor system is studied and numerically simulated by the computational fluid dynamics software FLUNET. The axial thrust of turbine expander is analyzed, and the mechanical analysis model and the integral 3D model of impeller clearance and impeller seal are established. The low re number k- 蔚 model and SIMPLEC algorithm in FLUNET software are used to consider the effects of leakage, compressibility and viscosity of gas. The axial thrust of turbine expander is simulated. The variation trend of axial force and clearance leakage is simulated when the seal clearance increases due to mechanical wear. The numerical results show that the axial force and clearance leakage increase with the increase of the gap between the seal teeth and the rotor. The axial force of the impeller clearance decreases gradually, and the leakage of the clearance increases with the increase of the clearance. The irrelevance of the mesh is verified, and the numerical simulation results are compared with the calculated results of the theoretical formula. The reasons for the difference between the two are found. The variation of axial thrust of turbine expander with different seal cavities on the clearance side of impeller is analyzed, and the pressure distribution, velocity distribution along axial direction and clearance leakage amount of impeller side are calculated. The axial force of impeller clearance under different seal cavities is compared and analyzed. The change of axial force of turbine expander during straight tooth seal is studied, and the leakage amount and axial force of impeller clearance in straight tooth seal and oblique tooth seal are compared and analyzed, and the cause of the difference is analyzed. It provides a direction for the turbine expander to improve the efficiency of the unit and increase the stability of the unit.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB653

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