气流力作用下的转子动力学特性研究

发布时间：2018-06-29 03:04

本文选题：叶顶间隙气流力 + 密封力　；参考：《华中科技大学》2011年硕士论文

【摘要】：随着各国经济的快速发展,用电量的需求也极具增加。但是作为发电主要机组的火力发电,其必需的煤炭等不可再生资源的储存量却日渐减少。因此,研制、生产和发展节能的大型汽轮机组成为火力发电的必然趋势。然而,随着汽轮机蒸汽参数的不断提高,产生的气流激振力也随之增大,而且会有继续严重的发展趋势,最终影响汽轮机的安全运行。因此,研究转子在气流力作用下的运动特性也越来越重要。本文首先介绍了引发气流激振的两种主要气流力,密封力和由叶轮偏心引起的叶顶间隙气流力。并且分别建立了两种气流力的模型,以及转子模型。然后以Matlab为主要的计算工具,对两种气流力作用下的转子动力学方程进行了数值计算。本文主要由理论分析转子稳定性和数值计算分析分析转子运动特性两部分组成。在理论分析的部分,主要分析了平衡转子系统在密封力单独作用下的稳定性以及叶顶间隙气流激振力及其影响因素的关系。分析认为,在密封力的单独作用下,存在使转子发生Hopf分岔的临界转速。而叶顶间隙气流激振力的大小则随出气角度和叶顶间隙的而减小,随进气速度、进气角度以及气流密度的增大而增大。在数值计算的部分,分别计算了转子系统无质量偏心和有质量偏心时的转子动力学微分方程。其中,对平衡转子的计算结果验证了理论分析中转子会发生Hopf分岔的结论。对不平衡转子的计算结果显示,在二者的共同作用下,随转速的增大转子从单周期运动经过倍周期或者概周期运动最终变化到混沌状态。并且结果显示,在转速较小时叶顶间隙气流力对转子的作用较大,但随着转速的不断增大,其对转子的影响逐渐变弱;相反,密封力对转子的影响随着转速的增大而增大。
[Abstract]:With the rapid development of national economy, the demand for electricity consumption is also increasing. However, as the main generating unit, the storage of non-renewable resources, such as coal, is decreasing day by day. Therefore, the research, production and development of energy-saving large steam turbine composition is the inevitable trend of thermal power generation. However, with the continuous improvement of steam turbine parameters, the generated airflow excitation force will also increase, and will continue to have a serious trend of development, and ultimately affect the safe operation of steam turbines. Therefore, it is more and more important to study the motion characteristics of rotor under the action of airflow force. In this paper, two main kinds of airflow force, seal force and airflow force of tip clearance caused by eccentricity of impeller are introduced. The model of two kinds of airflow force and the model of rotor are established respectively. Then, the rotor dynamic equations under two kinds of airflow forces are numerically calculated with Matlab as the main calculation tool. This paper mainly consists of two parts: theoretical analysis of rotor stability and numerical analysis of rotor motion characteristics. In the part of theoretical analysis, the stability of the balanced rotor system under the action of sealing force alone and the relationship between the airflow excitation force of the blade tip clearance and its influencing factors are mainly analyzed. It is considered that there is a critical speed of Hopf bifurcation in the rotor under the action of sealing force alone. However, the magnitude of the airflow excitation force of the tip clearance decreases with the outlet angle and the blade tip gap, and increases with the increase of the inlet velocity, the inlet angle and the air density. In the part of numerical calculation, the differential equations of rotor dynamics with mass eccentricity and mass eccentricity are calculated respectively. The calculation results of the balanced rotor verify the conclusion that Hopf bifurcation will occur in the theoretical analysis. The results of the calculation of the unbalanced rotor show that the rotor changes to chaos state with the increase of the speed of the rotor from the one-cycle motion to the periodic motion or the almost periodic motion. The results show that when the rotor speed is small, the effect of airflow force on rotor is great, but with the increase of rotor speed, the effect of seal force on rotor becomes weaker, and the effect of seal force on rotor increases with the increase of rotor speed.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TK261;TH113

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