基于完全耦合算法的绕水翼流固耦合特性研究

基于完全耦合算法对绕二维NACA0009水翼流固耦合特性进行了数值模拟研究。采用Theodorsen模型和Munch模型对刚性和弹性水翼的水弹性响应进行了数值计算,分析了流体与结构的相互作用关系,研究了影响结构水弹性响应和流固耦合特性的因素。研究结果表明:考虑了流体黏性的Munch模型与基于势流理论的Theodorsen模型对气动弹性响应的数值计算结果基本一致,而Theodorsen模型由于没有考虑流体黏性在一定程度上低估了结构的水弹性响应。结构的惯性、阻尼和刚度力矩与流体的相应附加载荷均处于同一数量级,故流体与结构的相互作用不可忽略,尤其对于弹性水翼,流体的惯性、附加阻尼作用增大,流固耦合算法的数值稳定性对流固耦合特性的计算结果影响将更大。外部激励频率为非共振频率时,结构的刚度作用是影响水弹性响应的主要因素,外部激励频率为共振频率时,流体的附加阻尼和附加刚度作用减弱,除结构的刚度作用外,流体与结构的惯性作用对水弹性响应和流固耦合特性的影响也较大。

Fluid structure interaction analysis of a hydrofoil based on fully coupled algorithm

A fully coupled algorithm for modeling of fluid structure interaction in viscous flow around the NACA0009 hydrofoil is presented. The numerical simulations are performed by using the Theodorsen mod-el and the Munch model to investigate the fluid structure interaction and characterize the factors that sig-nificantly affect the hydroelastic responses. It is revealed that Theodorsen 's approximation of the hydroe-lastic moment is based on inviscid, potential flow theory and hence it underestimated the hydroelastic re-sponses to some extent. The fluid inertial, damping, and stiffness forces are not negligible compared to their structural counterparts. For the flexible hydrofoil, the fluid inertial and damping forces increase, suggesting that the numerical instability of fluid structure coupling algorithms may lead to a more significant impact on the numerical prediction of the fluid structure interactions. Meanwhile, the structural stiffness dominates the response of the hydrofoil when the external excitation frequency is set to be the non-resonance frequen-cy, while as the external excitation frequency equals to the resonance frequency, the effect of the fluid damp-ing and stiffness is less significant and the structural response of this case is dominated by the fluid and solid inertial effects in addition to the structural stiffness.