The rationale behind this research is the development of a zero-heM floating system using a conventional hydrokinetic water wheel as a model to examine and determine its performance in an open channel condition for en...The rationale behind this research is the development of a zero-heM floating system using a conventional hydrokinetic water wheel as a model to examine and determine its performance in an open channel condition for energy harvesting in Nigeria. The power is determined by flow of water in the stream which is responsible for rotating the blades. The research entails the water flow driven by a pump at 0.4 m/s and 0.6 m/s water velocities around a pool. The turbine is made to float under this free stream velocity. Feasibility study of its viability in Gari dam in Kano state of Nigeria was carried out and an average flow and discharge were determined during the dry season. Findings of this research were quite impressive and can be used to design a suitable floating zero-head turbine for energy harvesting in Nigerian rural areas where the head is low and energy is required not only for mechanization but also for lighting and irrigation purpose.展开更多
Numerical simulations and the control of self-propelled swimming of three-dimensional bionic fish in a viscous flow and the mechanism of fish swimming are carried out in this study,with a 3D computational fluid dynami...Numerical simulations and the control of self-propelled swimming of three-dimensional bionic fish in a viscous flow and the mechanism of fish swimming are carried out in this study,with a 3D computational fluid dynamics package,which includes the immersed boundary method and the volume of fluid method,the adaptive multi-grid finite volume method,and the control strategy of fish swimming.Firstly,the mechanism of 3D fish swimming was studied and the vorticity dynamics root was traced to the moving body surface by using the boundary vorticity-flux theory.With the change of swimming speed,the contributions of the fish body and caudal fin to thrust are analyzed quantitatively.The relationship between vortex structures of fish swimming and the forces exerted on the fish body are also given in this paper.Finally,the 3D wake structure of self-propelled swimming of 3D bionic fish is presented.The in-depth analysis of the 3D vortex structure in the role of 3D biomimetic fish swimming is also performed.展开更多
The secondary flow within a passage of turbomachinery exhibits a complex flow pattern by the effect of the centrifugal and the Coriolis forces. The passage vortex in this secondary flow generates a major part of the l...The secondary flow within a passage of turbomachinery exhibits a complex flow pattern by the effect of the centrifugal and the Coriolis forces. The passage vortex in this secondary flow generates a major part of the losses. However, the mechanism of the loss generation has not been fully clarified yet. In this point of view, the passage vortex is closely examined by the computational method using the two-dimensional curved square ducts as fundamental models. The inlet boundary layer thickness and the inlet velocity distortion are considered to be the major parameters affecting the generation of passage vortex in the present study. The computed results revealed that the passage vortex gave the predominant effects for the generation of loss not only in the breakdown process but also in the development process.展开更多
Motivation of this work has its origin in the boundary layer control for aeronautics and turbomachinery. For thatpurpose boundary layer can be modified by perforated plates with holes of specific sizes. The questions ...Motivation of this work has its origin in the boundary layer control for aeronautics and turbomachinery. For thatpurpose boundary layer can be modified by perforated plates with holes of specific sizes. The questions whichrise in such configuration are related to the existence of optimal size of the holes and the influence of microscalephenomena on the global flow patterns. This paper concentrates on the issue of the entrance effects on the microchannelflow. It is shown that mass flow rate is only insignificantly influenced by slip effects. Global parameterssuch as pressure difference and geometrical shape in more pronounced way alter flow behavior. In this paper weconcentrate on the numerical investigation of the microchannel flow for Kn < 0.01 and Re < 500. The channellength is finite. Hence, entrance and outlet effects on microchannel flow can be studied.展开更多
文摘The rationale behind this research is the development of a zero-heM floating system using a conventional hydrokinetic water wheel as a model to examine and determine its performance in an open channel condition for energy harvesting in Nigeria. The power is determined by flow of water in the stream which is responsible for rotating the blades. The research entails the water flow driven by a pump at 0.4 m/s and 0.6 m/s water velocities around a pool. The turbine is made to float under this free stream velocity. Feasibility study of its viability in Gari dam in Kano state of Nigeria was carried out and an average flow and discharge were determined during the dry season. Findings of this research were quite impressive and can be used to design a suitable floating zero-head turbine for energy harvesting in Nigerian rural areas where the head is low and energy is required not only for mechanization but also for lighting and irrigation purpose.
基金the support of National Natural Science Foundation of China (Grant No.10672183)
文摘Numerical simulations and the control of self-propelled swimming of three-dimensional bionic fish in a viscous flow and the mechanism of fish swimming are carried out in this study,with a 3D computational fluid dynamics package,which includes the immersed boundary method and the volume of fluid method,the adaptive multi-grid finite volume method,and the control strategy of fish swimming.Firstly,the mechanism of 3D fish swimming was studied and the vorticity dynamics root was traced to the moving body surface by using the boundary vorticity-flux theory.With the change of swimming speed,the contributions of the fish body and caudal fin to thrust are analyzed quantitatively.The relationship between vortex structures of fish swimming and the forces exerted on the fish body are also given in this paper.Finally,the 3D wake structure of self-propelled swimming of 3D bionic fish is presented.The in-depth analysis of the 3D vortex structure in the role of 3D biomimetic fish swimming is also performed.
文摘The secondary flow within a passage of turbomachinery exhibits a complex flow pattern by the effect of the centrifugal and the Coriolis forces. The passage vortex in this secondary flow generates a major part of the losses. However, the mechanism of the loss generation has not been fully clarified yet. In this point of view, the passage vortex is closely examined by the computational method using the two-dimensional curved square ducts as fundamental models. The inlet boundary layer thickness and the inlet velocity distortion are considered to be the major parameters affecting the generation of passage vortex in the present study. The computed results revealed that the passage vortex gave the predominant effects for the generation of loss not only in the breakdown process but also in the development process.
文摘Motivation of this work has its origin in the boundary layer control for aeronautics and turbomachinery. For thatpurpose boundary layer can be modified by perforated plates with holes of specific sizes. The questions whichrise in such configuration are related to the existence of optimal size of the holes and the influence of microscalephenomena on the global flow patterns. This paper concentrates on the issue of the entrance effects on the microchannelflow. It is shown that mass flow rate is only insignificantly influenced by slip effects. Global parameterssuch as pressure difference and geometrical shape in more pronounced way alter flow behavior. In this paper weconcentrate on the numerical investigation of the microchannel flow for Kn < 0.01 and Re < 500. The channellength is finite. Hence, entrance and outlet effects on microchannel flow can be studied.
