【作者】 胡绚；

【导师】 高德平；

【作者基本信息】 南京航空航天大学 ， 航空宇航推进理论与工程， 2007， 博士

【摘要】 反向旋转的双转子系统已被相当一部分航空发动机采用,以利于减小高、低压转子陀螺力矩的影响,降低机匣负荷,提高飞机机动性能。为了满足先进航空发动机研制的需要,进行反向旋转双转子系统动力学特性的研究十分必要。本文研究了两种不同中介支承联接方式的双转子结构,即中介轴承内圈与低压转子联接、外圈与高压转子联接,和中介轴承外圈与低压转子联接、内圈与高压转子联接。针对这两种反向旋转双转子结构的动力特性,本文开展了以下工作:(1)建立了双转子系统动力学分析模型,发展了直接传递矩阵法,研究了双转子系统临界转速特性,分析了支承刚度、转速比和陀螺力矩对其临界转速的影响规律以及转子系统应变能的分布,比较了两种反向旋转双转子系统临界转速特性的异同点,并通过试验验证了支承刚度对双转子系统临界转速的影响规律。研究表明陀螺力矩是同向旋转与反向旋转双转子临界转速特性存在差异的主要原因。(2)应用直接传递矩阵法,分析了轮盘的形心轨迹和质心位置变化规律,研究了反向旋转双转子系统的稳态不平衡响应,并通过试验进行了验证。研究结果表明:反向旋转双转子系统依次通过以某转子为主激励的临界转速时,主激励转子盘会依次发生质心转向。(3)考虑中介轴承的变刚度振动,分析了不同旋转方向下中介轴承刚度的非线性变化规律。在分析中介轴承各构件运动特点和所受载荷的基础上,建立了中介轴承动力特性分析模型,研究了不同的工作方式对中介轴承滚子自转转速、保持架转速以及滚子载荷的影响,对比了它们的工作性能。研究结果表明:反向旋转的中介轴承受载滚子数目较多,打滑率较低,可延长其疲劳寿命;但滚子自转转速较高,会缩短滚子的疲劳寿命,所以两种旋转方向的中介轴承各有利弊,应据具体情况具体分析。(4)考虑中介轴承刚度的非线性变化,推导了反向旋转双转子系统振动响应的非线性动力学方程,研究了转子转速、不平衡量和中介轴承径向间隙对系统响应特性的影响规律。研究结果表明:通过适当地选取转速与不平衡量,可以降低转子-轴承系统的非线性振动;减少中介轴承的径向间隙,有利于系统的非周期运动转变为周期运动,提高系统运动的平稳性。综上所述,本文较系统地研究了反向旋转双转子系统临界转速特性、稳态不平衡响应特性、中介轴承动力特性以及非线性振动响应等问题。研究结果对于提高航空发动机转子系统的动力学性能,指导双转子系统的设计和使用具有重要的理论意义和工程应用价值。更多还原

【Abstract】 The counter-rotating dual-rotor system is applied in some aero-engines, and it can decrease the influence of the gyroscopic moments created by the high pressure rotor and the low pressure rotor, reduce the torque of cases, and improve the flexibility of airplanes. So the research on the dynamical characteristics of the dual-rotor system is essential in order to meet the development of the high-performance aero-engines. Two kinds of dual-rotor systems, which have different inter-shaft connecting structures, are studied. In one of the dual-rotor systems, the low pressure rotor is mounted on the inter-shaft bearing’s inner ring and the high pressure rotor is mounted on the inter-shaft bearing’s outer ring. In the other, the low pressure rotor is mounted on the inter-shaft bearing’s outer ring and the high pressure rotor is mounted on the inter-shaft bearing’s inner ring. The main contents of this paper are as follows.(1) The direct transfer matrix method is developed, and the dynamical model of the dual-rotor system is set up. Using the model, the critical speed characteristics are studied, and the distributions of the system’s strain energy and the influences of the supporter’s stiffness, the speed ratio and the gyroscopic moments to the critical speeds are analyzed. Then the critical speed characteristics of two kinds of dual-rotor systems are compared. Furthermore, the experiments results on the influences of the supporter’s rigidity to the critical speeds are given, and the laws from the calculation results are the same as those from the experiment results. It is found that, the gyroscopic moments is the primary reason of the difference between the critical speed characteristics of the dual-rotor systems which have different rotating directions.(2) The steady-state response of dual-rotor systems is studied by the direct transfer matrix method. The orbit and location of the centroids of dual-rotor disks are analyzed, and the calculational conclusions are validated by the experiments. It is found that, when the dual-rotor system passes the critical speed, the disk centroid location excited by itself will turn about 180 degrees, but another rotor won’t.(3) Considering the effect of the varying compliance vibration of the inter-shaft bearing, the non-linear changing rule of the inter-shaft bearing stiffness is analyzed when the bearing co-rotates and counter-rotates. Based on the analyses of motion and load relations, the analytic model of the inter-shaft bearing’s dynamical characteristics is set up. The roller spinning speed, the cage speed and the load of rollers are analyzed, and the performances of theinter-shaft bearings are compared, when the bearing operating in different working conditions. The conclusion indicates that, the counter-rotating inter-shaft bearing has more loaded rollers, lower slip ratio, but it has higher roller spinning speeds, so each of the inter-shaft bearings for two rotating directions possesses the respective advantage.(4) Considering the non-linear stiffness of inter-shaft bearings, the dynamical equation for the non-linear vibration analysis of the counter-rotating dual-rotor systems is given. The influences of the rotor speeds, the amount of unbalance, and the radial clearance of inter-shaft bearings to the system response characteristics are studied. It is found that, the non-linear vibration can be reduced by selecting the parameters, including the rotor speed and the amount of unbalance. The non-periodic vibration can be avoided by decreasing the radial clearance of inter-shaft bearings.In conclusion, the critical speed characteristics, the steady-state response, the dynamical characteristics of inter-shaft bearings and the non-linear vibration response of the counter-rotating dual-rotor systems are studied in this paper. The results can provide the theoretical direction for the design and the operation of dual-rotor system, and it is helpful to gain higher dynamical characteristics of the dual-rotor sytems of aero-engines, so the contribution possesses an important theoretical significance and application value in engineering.更多还原