柱面螺旋槽干气密封稳态流场特性研究

发布时间：2018-05-25 04:28

本文选题：柱面螺旋槽干气密封 + PH线性化　；参考：《兰州理工大学》2017年硕士论文

【摘要】：在形式多样的非接触式密封中,干气密封作为一种新型的、先进的轴端密封,因其优良的密封性能、较长的使用寿命和运行过程中的低磨损量,在旋转流体机械中得到了广泛的应用。近年来,随着流体机械不断向高温、高速、高压的方向发展,对于旋转机械的轴端密封也就提出了更高的要求。本文针对烟气轮机和燃气轮机高温大振幅的工况特性,提出了一种能适应这种工况的柱面螺旋槽干气密封。主要研究了柱面气膜的压力分布以及柱面密封的稳态特性。本文根据柱面螺旋槽密封的特点,建立了考虑滑移边界条件下的稳态柱面雷诺方程。在相关文献的基础上,建立了含有螺旋槽结构参数的气膜厚度函数关系式。在膜厚方程和压力边界条件的控制下,利用PH线性化和小参数迭代等数学方法,求解出了柱面螺旋槽气膜压力分布的函数近似解析解。通过MATLAB软件进行编程,获得了在特定工况下柱面气膜的三维压力分布情况,并对指定工况下的柱面螺旋槽密封稳态特性进行了求解,获得了柱面螺旋槽密封的气膜浮升力、密封泄漏量和摩擦转矩等参数的大小。同时,计算了偏心率存在情况下,无螺旋槽柱面密封和无偏心率存在情况下,螺旋槽柱面密封的压力分布和稳态特性,并与柱面螺旋槽干气密封计算结果进行对比分析。在上述基础上,针对不同的螺旋槽参数和工况参数,分析了气膜压力分布与螺旋槽槽数、槽深、偏心率和密封宽度之间的变化规律。同时,也讨论了不同结构工况参数下,气膜浮升力、密封泄漏量和摩擦转矩的变化规律。通过综合以上研究分析结果,提出了部分优化的螺旋槽结构参数。结果表明:槽数、槽深、偏心率的增大,都会导致压力峰值逐渐增大;而密封宽度对压力峰值影响不大。在不同偏心率下,槽数的变化对气膜浮升力的影响不明显,但是会导致摩擦转矩的升高,泄漏量会下降至稳定值。随着槽深的增加,气膜浮升力下降,泄漏量和摩擦转矩都增加。随着密封宽度的增加,气膜浮升力变大,泄漏量减小。螺旋角的增加使得气膜浮升力下降,摩擦转矩和泄漏量上升。推荐了优化槽数为12~18,密封宽度为0.03~0.045m,螺旋角为40°~50°。对后续的理论研究和工程应用提供了一定的依据和参考。
[Abstract]:In various forms of non-contact seal, dry gas seal as a new type of advanced shaft end seal, because of its excellent sealing performance, long service life and low wear during operation, It is widely used in rotating fluid machinery. In recent years, with the development of fluid machinery towards high temperature, high speed and high pressure, higher requirements for shaft end sealing of rotating machinery have been put forward. In this paper, according to the characteristics of high temperature and large amplitude of flue gas turbine and gas turbine, a cylinder spiral groove dry gas seal is proposed. The pressure distribution of cylinder film and the steady state characteristics of cylinder seal are studied. In this paper, according to the characteristics of cylindrical spiral groove seal, the steady cylinder Reynolds equation considering slip boundary condition is established. On the basis of related literatures, the functional expression of film thickness with structural parameters of spiral groove is established. Under the control of film thickness equation and pressure boundary condition, the approximate analytical solution of film pressure distribution in cylindrical spiral groove is obtained by using PH linearization and small parameter iteration. The three-dimensional pressure distribution of cylinder film is obtained by programming with MATLAB software, and the steady state characteristics of cylinder spiral groove seal under specified working condition are solved, and the floating force of cylinder spiral groove seal is obtained. Sealing leakage and friction torque and other parameters of the size. At the same time, the pressure distribution and steady state characteristics of spiral groove cylinder seal under the condition of eccentricity, unhelical groove cylinder seal and unbiased heart rate are calculated and compared with the calculated results of cylinder spiral groove dry gas seal. On the basis of the above, according to different helical groove parameters and operating conditions, the variation of film pressure distribution and the number of spiral grooves, groove depth, eccentricity and seal width are analyzed. At the same time, the variation law of film floating lift, seal leakage and friction torque are also discussed. Based on the above analysis results, some optimized structural parameters of spiral grooves are proposed. The results show that the increase of slot number, groove depth and eccentricity will result in a gradual increase of the pressure peak value, while the seal width has little effect on the pressure peak value. Under different eccentricity, the influence of the number of slots on the lift of the film is not obvious, but the friction torque will increase and the leakage will decrease to the stable value. With the increase of groove depth, the lift of film float decreases, the leakage and friction torque increase. With the increase of seal width, the lift of film float increases and the leakage decreases. The increase of spiral angle decreases the lift of the film and increases the friction torque and leakage. It is recommended that the optimized slot number be 12 ~ 18, the seal width 0.03 ~ 0. 045 m and the helical angle 40 掳~ 50 掳. It provides a certain basis and reference for the subsequent theoretical research and engineering application.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH136

【参考文献】