Energy method for the vibration of two types of cylindrical shells,namely thin-walled homogeneous isotropic and manifold layered isotropic cylindrical shells under uniform external lateral pressure is presented.The st...Energy method for the vibration of two types of cylindrical shells,namely thin-walled homogeneous isotropic and manifold layered isotropic cylindrical shells under uniform external lateral pressure is presented.The study is carried out based on strain-displacement relationship from Love's shell theory with beam functions as axial modal function.A manifold layered cylindrical shell configuration is formed by three layers of isotropic material where the inner and outer layers are stainless steel and the middle layer is aluminum.The homogeneous cylindrical shell is made-up of isotropic one layer with stainless steel.The governing equations with uniform external lateral pressure for homogeneous isotropic and manifold layered isotropic cylindrical shells are obtained using energy functional by the Lagrangian function with Rayleigh-Ritz method.The boundary conditions that are presented at the end conditions of the cylindrical shell are simply supported-simply supported,clamped-clamped and free-free.The influences of uniform external lateral pressure and symmetrical boundary conditions on the natural frequency characteristics for both homogeneous and manifold layered isotropic cylindrical shells are examined.For all boundary conditions considered,the natural frequency of both cylindrical shells with symmetric uniform lateral pressure increases as h/R ratio increases and those considering natural frequency of the both cylindrical shells with symmetric uniform lateral pressure decrease as L/R ratio increases.展开更多
Wave energy is one of the renewable energy sources with the highest potential.Several pilot plants have been built based on the principle of the Oscillating Water Column(OWC).Among the different solutions that have be...Wave energy is one of the renewable energy sources with the highest potential.Several pilot plants have been built based on the principle of the Oscillating Water Column(OWC).Among the different solutions that have been suggested,the Wells turbine has gained particular attention due to its simplicity and reliability.The majority of available studies concentrate on the steady operation of the Wells turbine,while only few analyze its performance under an unsteady and bi-directional air flow,as determined by the presence of the OWC system.In this work,experimental and numerical performance of a high-solidity Wells turbine with NACA0015 profiles have been compared,at different non-dimensional piston frequencies.The numerical simulations have been conducted using commercial CFD software and focus on unsteady predictions,with particular attention to the behavior of the flow upstream and downstream of the rotor,flow hysteresis between acceleration and deceleration phases and differences between intake and exhaust strokes due to the non-symmetrical configuration of the machine.展开更多
文摘Energy method for the vibration of two types of cylindrical shells,namely thin-walled homogeneous isotropic and manifold layered isotropic cylindrical shells under uniform external lateral pressure is presented.The study is carried out based on strain-displacement relationship from Love's shell theory with beam functions as axial modal function.A manifold layered cylindrical shell configuration is formed by three layers of isotropic material where the inner and outer layers are stainless steel and the middle layer is aluminum.The homogeneous cylindrical shell is made-up of isotropic one layer with stainless steel.The governing equations with uniform external lateral pressure for homogeneous isotropic and manifold layered isotropic cylindrical shells are obtained using energy functional by the Lagrangian function with Rayleigh-Ritz method.The boundary conditions that are presented at the end conditions of the cylindrical shell are simply supported-simply supported,clamped-clamped and free-free.The influences of uniform external lateral pressure and symmetrical boundary conditions on the natural frequency characteristics for both homogeneous and manifold layered isotropic cylindrical shells are examined.For all boundary conditions considered,the natural frequency of both cylindrical shells with symmetric uniform lateral pressure increases as h/R ratio increases and those considering natural frequency of the both cylindrical shells with symmetric uniform lateral pressure decrease as L/R ratio increases.
文摘Wave energy is one of the renewable energy sources with the highest potential.Several pilot plants have been built based on the principle of the Oscillating Water Column(OWC).Among the different solutions that have been suggested,the Wells turbine has gained particular attention due to its simplicity and reliability.The majority of available studies concentrate on the steady operation of the Wells turbine,while only few analyze its performance under an unsteady and bi-directional air flow,as determined by the presence of the OWC system.In this work,experimental and numerical performance of a high-solidity Wells turbine with NACA0015 profiles have been compared,at different non-dimensional piston frequencies.The numerical simulations have been conducted using commercial CFD software and focus on unsteady predictions,with particular attention to the behavior of the flow upstream and downstream of the rotor,flow hysteresis between acceleration and deceleration phases and differences between intake and exhaust strokes due to the non-symmetrical configuration of the machine.
