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密封动力特性对旋转机械转子系统稳定性影响较大,在密封入口端部设置阻旋栅是提高密封稳定性的有效方法。设计加工了无/有阻旋栅共5种密封结构,从数值分析与实验研究两个方面研究阻旋栅对密封静力与动力特性的影响规律。建立阻旋栅密封静力特性CFD理论模型,数值分析阻旋栅对密封泄漏量、切向速度以及周向压力分布的影响;应用不平衡同频激励法实验研究阻旋栅对密封动力特性的影响。研究结果表明:阻旋栅可降低密封的泄漏量,减小密封内流体的切向速度,进而降低密封内流体的周向压力差,且随着阻旋栅周向稠度与径向长度的增加,这种作用逐渐增大,这是阻旋栅抑制气流激振力的主要原因;预旋是密封产生交叉刚度的重要因素,密封的交叉刚度随进出口压比与转速的增加而增大;阻旋栅可有效降低密封的交叉刚度,增加密封的主阻尼,提高密封的稳定性。本文研究揭示了阻旋栅抑制密封气流激振力的机理,为设计阻旋栅密封提供理论依据。
The dynamic characteristics of the seal have a great influence on the stability of the rotating machinery rotor system. Setting the stop ring on the end of the seal inlet is an effective method to improve the seal stability. A total of five kinds of seal structures were designed and fabricated without / with a hinged grid. The influence of resistance grid on the static and dynamic characteristics of the seal was studied from two aspects of numerical analysis and experimental study. The CFD theoretical model of the static characteristics of the resistance-locked gable seal was established. The influence of the resistance gating grid on the leakage, the tangential velocity and the circumferential pressure distribution was analyzed numerically. The unbalanced excitation method was used to study the influence of the resistance gating on the dynamic characteristics of the seal influences. The results show that the resistance rotating grid can reduce the leakage of the seal, reduce the tangential velocity of the fluid in the seal, and then reduce the circumferential pressure difference of the fluid in the seal. With the increase of the circumferential consistency and radial length , This effect is gradually increased, which is the main reason that the arresting grid inhibits the airflow exciting force. Pre-rotation is an important factor for the cross-stiffness of the seal. The cross-stiffness of the seal increases with the increase of the pressure ratio and speed of the inlet and outlet. Resistive grid can effectively reduce the cross-seal stiffness, increase the main seal damping, improve seal stability. This study reveals the mechanism of the hindered gate inhibiting the excitation force of the seal gas flow and provides a theoretical basis for the design of the resistive gate seal.