基于全隐式无分裂方法,数值求解三维非定常雷诺平均的N av ier-S tokes方程,紊流模型采用修正的B-L代数模型。运用此方法,本文数值模拟了三维开式空腔的超声速、跨声速、亚声速流动。研究了空腔口处剪切层的非定常运动现象,着重探讨了...基于全隐式无分裂方法,数值求解三维非定常雷诺平均的N av ier-S tokes方程,紊流模型采用修正的B-L代数模型。运用此方法,本文数值模拟了三维开式空腔的超声速、跨声速、亚声速流动。研究了空腔口处剪切层的非定常运动现象,着重探讨了入口边界条件对三维空腔流自持性振荡的影响。数值计算结果表明,与层流速度型相比,入口条件为紊流速度型和特征边界型得到的结果能够吻合。展开更多
In this paper, it is studicd the characteristics of flow-induced oscillation and sound radiation of streamlined protuberant special cavities. From which three important conclusions are drawn. The first, in water and i...In this paper, it is studicd the characteristics of flow-induced oscillation and sound radiation of streamlined protuberant special cavities. From which three important conclusions are drawn. The first, in water and in casc of low Mach number, there exist two oscillating modes in the cavity: natural oscillation and hydrodynamic oscillation of the cavity. The second, the cquation between Strouhal number and Mach number of hydrodynamic oscillation is put forward.The third, in water and in case of low Mach number, the equation of the incre ment of general sound level of flow-induced oscillation in direct proportion to square of flow rate is given.展开更多
This study investigates the torsional galloping phenomenon, an instability type flow-induced oscillation, in an elastic stru-cture due to hydrodynamic loads into the water current. The structure applied here is a rect...This study investigates the torsional galloping phenomenon, an instability type flow-induced oscillation, in an elastic stru-cture due to hydrodynamic loads into the water current. The structure applied here is a rectangular flat plate with an elastic axis in its mid-chord length. The elasticity is provided by torsion spring. The flat plate has only one degree of freedom which is rotation in pure yaw about its axis. It is observed that as the current speed is higher than a critical velocity, the flat plate becomes unstable. The instability leads to torsional galloping occurrence, as a result of which the flat plate begins to yaw about the elastic axis. By testing two different chord lengths each with several torsion spring rates, the flat plate behavior is investigated and three different responses are recognized. Then, a phenomenological model is developed with the original kernel in the form of the van der Pol-Duffing equa-tion. The model explains these three responses observed experimentally.展开更多
文摘基于全隐式无分裂方法,数值求解三维非定常雷诺平均的N av ier-S tokes方程,紊流模型采用修正的B-L代数模型。运用此方法,本文数值模拟了三维开式空腔的超声速、跨声速、亚声速流动。研究了空腔口处剪切层的非定常运动现象,着重探讨了入口边界条件对三维空腔流自持性振荡的影响。数值计算结果表明,与层流速度型相比,入口条件为紊流速度型和特征边界型得到的结果能够吻合。
文摘In this paper, it is studicd the characteristics of flow-induced oscillation and sound radiation of streamlined protuberant special cavities. From which three important conclusions are drawn. The first, in water and in casc of low Mach number, there exist two oscillating modes in the cavity: natural oscillation and hydrodynamic oscillation of the cavity. The second, the cquation between Strouhal number and Mach number of hydrodynamic oscillation is put forward.The third, in water and in case of low Mach number, the equation of the incre ment of general sound level of flow-induced oscillation in direct proportion to square of flow rate is given.
基金CNPq(Conselho Nacional da Pequisa)COPPETEC foundation(Coordenao de Projetos,Pesquisas e Estudos Tecnológicos)for the funding
文摘This study investigates the torsional galloping phenomenon, an instability type flow-induced oscillation, in an elastic stru-cture due to hydrodynamic loads into the water current. The structure applied here is a rectangular flat plate with an elastic axis in its mid-chord length. The elasticity is provided by torsion spring. The flat plate has only one degree of freedom which is rotation in pure yaw about its axis. It is observed that as the current speed is higher than a critical velocity, the flat plate becomes unstable. The instability leads to torsional galloping occurrence, as a result of which the flat plate begins to yaw about the elastic axis. By testing two different chord lengths each with several torsion spring rates, the flat plate behavior is investigated and three different responses are recognized. Then, a phenomenological model is developed with the original kernel in the form of the van der Pol-Duffing equa-tion. The model explains these three responses observed experimentally.
