A general purpose viscous flow solver Ansys CFX was used to study a Savonius type wave energy converter in a 3D numerical viscous wave tank.This paper presents the results of a computational fluid dynamics(CFD) analys...A general purpose viscous flow solver Ansys CFX was used to study a Savonius type wave energy converter in a 3D numerical viscous wave tank.This paper presents the results of a computational fluid dynamics(CFD) analysis of the effect of blade configuration on the performance of two Savonius rotors for wave energy extraction.A piston-type wave generator was incorporated in the computational domain to generate the desired incident waves.A complete OWC system with a 3-bladed Savonius rotor was modeled in a three dimensional numerical wave tank and the hydrodynamic conversion efficiency was estimated.The flow over the rotors was assumed to be two-dimensional(2D),viscous,turbulent and unsteady.The CFX code was used with a solver of the coupled conservation equations of mass,momentum and energy,with an implicit time scheme and with the adoption of the hexahedral mesh and the moving mesh techniques in areas of moving surfaces.Turbulence was modeled with the k-e model.The results indicated that the developed models are suitable to analyze the water flows both in the chamber and in the turbine.For the turbine,the numerical results of pressure and torque were compared for the two cases.展开更多
There is an increasing interest in cross flow turbines(also known as Banki turbines) for small and low head applications because of their simple structure as well as low capital and maintenance costs.The present work ...There is an increasing interest in cross flow turbines(also known as Banki turbines) for small and low head applications because of their simple structure as well as low capital and maintenance costs.The present work aims at implementing the direct drive turbine(DDT) of cross flow type for wave power generation.A numerical wave tank was used to simulate the waves and after obtaining the desired wave properties;the augmentation channel plus the front guide nozzle and rear chamber were integrated to the numerical wave tank.The waves in the numerical wave tank were generated by a piston type wave maker which was located at the wave tank inlet.The inlet which was modeled as a plate wall moved sinusoidally with the general function x = asinω t.The augmentation channel consisted of a front nozzle,rear nozzle and an internal fluid region which represented the turbine housing.The front and rear nozzles were geometrically the same.Three different front guide nozzle configurations were studied:a standard guide nozzle which was originally attached to the augmentation channel and two other front guide nozzles of different geometries.The purpose of this study is to observe how the front guide nozzle shape influences the flow downstream,mainly in the augmenta-tion channel,water power and the first stage energy conversion.The analysis was performed using a commercial CFD code ANSYS-CFX.The results of the flow in the augmentation channel for the three front guide nozzles are presented in this paper.展开更多
A bend-free rectangular cross-section OWC device was designed and constructed for studying the effect of inclination on the flow characteristics inside the device.The inclination is meant to reduce reflection of waves...A bend-free rectangular cross-section OWC device was designed and constructed for studying the effect of inclination on the flow characteristics inside the device.The inclination is meant to reduce reflection of waves and induce higher velocities in the turbine section.Experimental measurements were made in a wave channel where the OWC device was tested.An S-type Pitot tube was used to measure dynamic pressure of air in the turbine section at several inclinations.Particle Image Velocimetry(PIV)was also done to study the flow of both air and water in the OWC device.In order to focus solely on primary energy capture,no turbine was installed in the OWC device.The dynamic pressure readings were analysed for suction and compression stages.Water volume fluctuations inside the capture chamber were also recorded and compared for different inclinations.The result was an increase in the velocity of air flowing in the capture chamber and hence a rise in the kinetic energy available to the turbine.It was found from experimental studies that as the angle of inclination reduced,the velocity of air in the turbine section increased.The lower angles also caused higher run-up and larger volume of water into the capture chamber.展开更多
文摘A general purpose viscous flow solver Ansys CFX was used to study a Savonius type wave energy converter in a 3D numerical viscous wave tank.This paper presents the results of a computational fluid dynamics(CFD) analysis of the effect of blade configuration on the performance of two Savonius rotors for wave energy extraction.A piston-type wave generator was incorporated in the computational domain to generate the desired incident waves.A complete OWC system with a 3-bladed Savonius rotor was modeled in a three dimensional numerical wave tank and the hydrodynamic conversion efficiency was estimated.The flow over the rotors was assumed to be two-dimensional(2D),viscous,turbulent and unsteady.The CFX code was used with a solver of the coupled conservation equations of mass,momentum and energy,with an implicit time scheme and with the adoption of the hexahedral mesh and the moving mesh techniques in areas of moving surfaces.Turbulence was modeled with the k-e model.The results indicated that the developed models are suitable to analyze the water flows both in the chamber and in the turbine.For the turbine,the numerical results of pressure and torque were compared for the two cases.
文摘There is an increasing interest in cross flow turbines(also known as Banki turbines) for small and low head applications because of their simple structure as well as low capital and maintenance costs.The present work aims at implementing the direct drive turbine(DDT) of cross flow type for wave power generation.A numerical wave tank was used to simulate the waves and after obtaining the desired wave properties;the augmentation channel plus the front guide nozzle and rear chamber were integrated to the numerical wave tank.The waves in the numerical wave tank were generated by a piston type wave maker which was located at the wave tank inlet.The inlet which was modeled as a plate wall moved sinusoidally with the general function x = asinω t.The augmentation channel consisted of a front nozzle,rear nozzle and an internal fluid region which represented the turbine housing.The front and rear nozzles were geometrically the same.Three different front guide nozzle configurations were studied:a standard guide nozzle which was originally attached to the augmentation channel and two other front guide nozzles of different geometries.The purpose of this study is to observe how the front guide nozzle shape influences the flow downstream,mainly in the augmenta-tion channel,water power and the first stage energy conversion.The analysis was performed using a commercial CFD code ANSYS-CFX.The results of the flow in the augmentation channel for the three front guide nozzles are presented in this paper.
文摘A bend-free rectangular cross-section OWC device was designed and constructed for studying the effect of inclination on the flow characteristics inside the device.The inclination is meant to reduce reflection of waves and induce higher velocities in the turbine section.Experimental measurements were made in a wave channel where the OWC device was tested.An S-type Pitot tube was used to measure dynamic pressure of air in the turbine section at several inclinations.Particle Image Velocimetry(PIV)was also done to study the flow of both air and water in the OWC device.In order to focus solely on primary energy capture,no turbine was installed in the OWC device.The dynamic pressure readings were analysed for suction and compression stages.Water volume fluctuations inside the capture chamber were also recorded and compared for different inclinations.The result was an increase in the velocity of air flowing in the capture chamber and hence a rise in the kinetic energy available to the turbine.It was found from experimental studies that as the angle of inclination reduced,the velocity of air in the turbine section increased.The lower angles also caused higher run-up and larger volume of water into the capture chamber.
