火箭发动机涡轮盘模态影响因素与振动安全性分析

Analysis on modal influence factors and vibration safety of rocket engine turbine disk

涡轮盘结构模态特性及振动安全性是对其进行动力学设计的基础。首先,在模态试验的基础上,建立了准确的涡轮盘结构动力学模型;其次,开展多物理场作用下涡轮盘结构模态分析,研究轮盘工作时温度场、应力场及其耦合效应对模态特性的影响规律;最后,对轮盘振动安全性进行评价,给出其振动安全裕度。研究表明,离心力的旋转“刚化”作用使得模态频率升高,温度效应引起结构刚度减小使得频率降低,气动力引起结构“软化”使得频率下降;在力热综合作用下,对前6阶模态频率影响程度的大小顺序依次是转速、与温度相关的弹性模量、热应力及气动力,且气动力的影响可以忽略不计;力热载荷影响模态频率,但不影响模态振型;涡轮燃气激励起轮盘结构低阶节径模态行波耦合共振的可能性较小。

The modal characteristics and vibration safety of the turbine disk structure are the basis for its dynamics design.First,on the basis of the modal test,an accurate dynamic model of the disk was established.Secondly,the modal analysis was carried out under the effect of multi-physics field,which aimed at studying the influence of temperature field,stress field and coupling effect on the modal characteristics during the disk operating.Finally,the vibration safety of disk was evaluated to obtain its vibration safety margin.The research shows that,the rotational"stiffening"effect of centrifugal force increases the modal frequencies,the temperature effect causes the structural stiffness to decrease and the frequency to decrease,and the aerodynamic force causes the structure to"stiffening"and the frequency to reduce.Under the combined action of force and heat,the order of the degree of influence on the first 6-order modal frequencies are speed,temperature,elastic modulus,thermal stress and aerodynamic force,and the influence of aerodynamic force is negligible.The force and thermal load affect the modal frequency,but not the modal shape.Moreover,the possibility of low-order diameter modals traveling wave coupling resonance of the disk structure excited by turbine gas is very small.