The vortex-induced vibration of two identical rigidly mounted risers in a parallel arrangement was studied using Ansys-CFX and model tests.The vortex shedding and force were recorded to determine the effect of spacing...The vortex-induced vibration of two identical rigidly mounted risers in a parallel arrangement was studied using Ansys-CFX and model tests.The vortex shedding and force were recorded to determine the effect of spacing on the two-degree-of-freedom oscillation of the risers.CFX was used to study the single riser and two parallel risers in 2–8D spacing considering the coupling effect.Because of the limited width of water channel,only three different riser spacings,2D,3D,and 4D,were tested to validate the characteristics of the two parallel risers by comparing to the numerical simulation.The results indicate that the lift force changes significantly with the increase in spacing,and in the case of 3D spacing,the lift force of the two parallel risers reaches the maximum.The vortex shedding of the risers in 3D spacing shows that a variable velocity field with the same frequency as the vortex shedding is generated in the overlapped area,thus equalizing the period of drag force to that of lift force.It can be concluded that the interaction between the two parallel risers is significant when the risers are brought to a small distance between them because the trajectory of riser changes from oval to curve 8 as the spacing is increased.The phase difference of lift force between the two risers is also different as the spacing changes.展开更多
When the variable geometry hypersonic inlet is sealed with ceramic wafers,the cavity flows inside the sealing chamber can be affected by the boundary layer near the side wall.To study the influence of the boundary lay...When the variable geometry hypersonic inlet is sealed with ceramic wafers,the cavity flows inside the sealing chamber can be affected by the boundary layer near the side wall.To study the influence of the boundary layer thickness near the side wall on the flow and leakage characteristics in sealing chamber,the numerical calculation of the cavity flow in the sealing chamber under different inflow boundary layer thicknesses is carried out.The results show that three-dimensional cavity flow structures are close to being asymmetric,and the entrance pressure of the leakage path can also be affected by asymmetry;with the increase of the thickness of the boundary layer,the pressure at the cavity floor and the seal entrance decreases.Finally,the existing leakage prediction model is modified according to the distribution rule of the cavity floor and the flow properties in the leakage path.展开更多
基金This study is supported financially by the National Natural Science Foundation of China (Nos.51179179 and 51239008)
文摘The vortex-induced vibration of two identical rigidly mounted risers in a parallel arrangement was studied using Ansys-CFX and model tests.The vortex shedding and force were recorded to determine the effect of spacing on the two-degree-of-freedom oscillation of the risers.CFX was used to study the single riser and two parallel risers in 2–8D spacing considering the coupling effect.Because of the limited width of water channel,only three different riser spacings,2D,3D,and 4D,were tested to validate the characteristics of the two parallel risers by comparing to the numerical simulation.The results indicate that the lift force changes significantly with the increase in spacing,and in the case of 3D spacing,the lift force of the two parallel risers reaches the maximum.The vortex shedding of the risers in 3D spacing shows that a variable velocity field with the same frequency as the vortex shedding is generated in the overlapped area,thus equalizing the period of drag force to that of lift force.It can be concluded that the interaction between the two parallel risers is significant when the risers are brought to a small distance between them because the trajectory of riser changes from oval to curve 8 as the spacing is increased.The phase difference of lift force between the two risers is also different as the spacing changes.
基金supported by the Opening Foundation of National State Key Laboratory of High Temperature Gas Dynamics(No.2021KF07)。
文摘When the variable geometry hypersonic inlet is sealed with ceramic wafers,the cavity flows inside the sealing chamber can be affected by the boundary layer near the side wall.To study the influence of the boundary layer thickness near the side wall on the flow and leakage characteristics in sealing chamber,the numerical calculation of the cavity flow in the sealing chamber under different inflow boundary layer thicknesses is carried out.The results show that three-dimensional cavity flow structures are close to being asymmetric,and the entrance pressure of the leakage path can also be affected by asymmetry;with the increase of the thickness of the boundary layer,the pressure at the cavity floor and the seal entrance decreases.Finally,the existing leakage prediction model is modified according to the distribution rule of the cavity floor and the flow properties in the leakage path.
