舵-轴系统流致振动特性的影响因素

针对具有低质量比和小展弦比的舵-轴系统,设计了一种用以分析其流致振动特性的实验方案。使用一组拉伸弹簧模拟系统的扭转刚度,并利用精准的测量方法对系统的扭转刚度、重心位置以及转动惯量进行标定。实验在重力式水洞中进行,测量并分析了来流速度、支撑刚度、扭转刚度对系统振动形态以及颤振速度的影响。通过将实验值与数值计算结果进行比较,发现二者吻合良好。此外,利用两自由度运动方程分别计算了舵-轴系统在不同重心位置、刚心位置、初始攻角、舵的质量、弦长以及展长条件下的颤振速度,得到了各参数值的变化对系统振动特性的影响规律。由于在舵-轴系统的主要结构参数中,支撑刚度和扭转刚度、重心位置和刚心位置、舵的弦长和展长这三对参数各自存在着相关性,所以为了更全面了解参数变化对系统颤振速度的影响,进一步分析了每对参数同时变化对系统振动形态的影响。

Study on the influences of parameters on flow-induced vibrations of a hydrofoil-rod system

An experimental scheme was designed to analyze the flow induced vibration characteristics of a hydrofoil-rod system with a low mass ratio and a small aspect ratio. Torsional springs were used to make an equivalent torsional stiffness, and the torsional stiffness, the position of the center of gravity and the moment of inertia were obtained with accurate measure methods. Experiments were performed in a water tunnel, and the analysis of the influences of inflow velocity, bracing stiffness and torsional stiffness on the vibrations and flutter speed were based on the measurements. The comparison of flutter speeds between the calculation and experimental values shows that the experimental results are reasonable. Moreover, the effects of the locations of the center of gravity and of the elastic axis, the angle of attack, the mass of the hydrofoil etc. on flutter speed were discussed by resolving two-degree-of-freedom motion equations. There are correlations between three pair of main parameters --- bracing stiffness and torsional stiffness, the positions of the center of gravity and of the elastic axis, chord and span --- of the hydrofoil-rod system. The influences of the variations of each pair of the parameters on the vibration form are discussed to well understand the relation of parameters to flutter speed.