摘要
应用粒子图像测试技术(PIV)观测H形断面风致振动过程中模型表面的旋涡演化过程,采用相位平均的方法研究模型周期性振动与旋涡规律性演化之间的关系。结合计算流体动力学(CFD)的方法获得振动模型表面的压力场,并采用正交特征分解(POD)分析模型表面压力的模态特征函数,分析结果表明模型处于振动状态时的表面平均压力分布是不对称的,主要体现在上表面压力的分布是反对称的,下表面的压力是正对称的,平均压力的这种非对称分布产生了作用在结构的逆时针力矩,造成这种结构的气动稳定性相当差。根据POD分析结果对模型表面进行合理分区,利用分块分析的思想研究颤振过程气流能量输入特点。在一个周期内气流输入到H形断面的总能量具有波动变化的特点,当气流输入到系统的能量为正并且达到峰值后将持续较长时间,然后再缓慢降低,最后气流开始消耗系统能量。气流输入能量的这种波动变化特性决定了H形断面颤振前多表现为较长时间的大幅振动,而不是突然性的发散失稳。
The evolution process of the vortex on the model surface during the plate flutter was tested by the particle image velocimetry （PIV） technique. The relationship between the model periodic oscillation and vortex evolution law was studied by the phase-average method.. The model surface pressures were obtained by the computational fluid dynamics （CFD） numerical method. Mode characteristic function of model surface pressure was obtianed by the proper orthogonal decomposition （POD） technique. The results show that the average surface pressure distribution of the model is asymmetric. The upper surface pressure distribution is antisymmetric, while the lower surface pressure is symmetric. Such non-symmetrical average pressures produce the counter-clockwise moments in the structure, which leads to the poor aerodynamic stability of the structure. According to the results of POD analysis, reasonable partition of the model surface is made. The features of energy input during the flutter are studied by principle of block analysis. In one cycle, the total e energy input to the H-shaped section is fluctuating. The energy input to the system is positive and attainsto peak, which would continues for a longer time and then slowly decreases, finally begins to consume energy of system. The characteristics of energy fluctuating decided the H-shape cross section has the large amplitude vibration over a longer time before flutter, rather than sudden divergence instability.
出处
《土木工程学报》
EI
CSCD
北大核心
2013年第4期110-116,141,共8页
China Civil Engineering Journal
基金
国家自然科学基金(51208197
5102114005)
华北水利水电学院高层次人才资助项目
关键词
流场机理
粒子图像测速
H形断面
POD分解
分块分析
相位平均
flow mechanism
particle image velocimetry
H-shape section
POD decomposition
block analysis
phase average
