There exists inlet-engine match conflict between high and low speeds for a non-adjustable bump inlet.A scheme of using a bistable bump surface at the throat region of the inlet is proposed to adjust the throat area.Th...There exists inlet-engine match conflict between high and low speeds for a non-adjustable bump inlet.A scheme of using a bistable bump surface at the throat region of the inlet is proposed to adjust the throat area.The FEM model of the bistable surface is established with hinged constraint,and the bistability condition and structural transition process are investigated in detail.Moreover,the effects of loading method,loading position and structural parameters on critical driving force,input energy and structural strain are studied.Finally,the influences of an elastic boundary condition on the structural bistability are discussed.The results show that the bistability of the adjustable bump surface requires a certain boundary constraint and geometric parameter combination,and that there are local and overall snap-through phenomena during transition which are related to the loading position and structural parameters.Therefore,suitable loading position and structural material could reduce input energy and meet the demand of structural strain.展开更多
Three-dimensional(3D)Stokes flow of an incompressible fluid in a curved channel is analyzed.The flow field and characteristics under the influence of 3D surface bumps are studied.A mathematical model describing the 3D...Three-dimensional(3D)Stokes flow of an incompressible fluid in a curved channel is analyzed.The flow field and characteristics under the influence of 3D surface bumps are studied.A mathematical model describing the 3D complex flow in the curvilinear geometry is formulated and validated.The solution of the coupled system of quasilinear partial differential equations associated with the model is obtained analytically.The behavior of the velocity distribution as the fluid moves through the undulating passage of the bumpy curved channel is examined and explained for each velocity component.The analysis of this flow problem indicates that the velocity vector of the flow is significantly altered by the presence of the structures on the bounding bumpy surfaces,depending on the alignment of the bumps.Furthermore,it is found that the difference between the flow rate in the bumpy curved channel and that in a smooth curved channel is essentially a function of the geometric characteristics of the surface bumps and the curved channel.Notably,the flow in a bumpy straight channel is a limiting case of that in the bumpy curved channel,but the overall effect of the bumps is more significant for a bumpy curved channel.展开更多
The primary focus of the present survey is to categorize the results of various investigations on the Shock/Boundary-Layer Interactions(SBLIs),their repercussions,and the effective ways to control them.The interaction...The primary focus of the present survey is to categorize the results of various investigations on the Shock/Boundary-Layer Interactions(SBLIs),their repercussions,and the effective ways to control them.The interactions of shock waves with the boundary layer are an important area of research due to their ubiquity in several applications ranging from transonic to hypersonic flows.Therefore,there is a need for a detailed inspection to understand the phenomena to predict its characteristics with certain accuracy.Considering this in mind,this article presents some key features of the physical nature of SBLIs,their consequences,and the control techniques in a sequential manner;in particular,the passive control techniques for the supersonic and hypersonic intakes are reviewed in detail.展开更多
基金supported by the National Natural Science Foundation of China(Nos.11172128,51475228)the Specialized Research Fund for the Doctoral Program of Higher Education of China (No.20123218110001)+1 种基金the Research Fund of State Key Laboratory of Mechanics and Control of Mechanics Structures (Nanjing University of Aeronautics and Astronautics)(No.0515G01)the Priority Academic Program Development of Jiangsu Higher Education Institutions and the Funding of Jiangsu Innovation Program for Graduate Education(the Fundamental Research Funds for the Central Universities)(No.CXZZ12_ 0139)
文摘There exists inlet-engine match conflict between high and low speeds for a non-adjustable bump inlet.A scheme of using a bistable bump surface at the throat region of the inlet is proposed to adjust the throat area.The FEM model of the bistable surface is established with hinged constraint,and the bistability condition and structural transition process are investigated in detail.Moreover,the effects of loading method,loading position and structural parameters on critical driving force,input energy and structural strain are studied.Finally,the influences of an elastic boundary condition on the structural bistability are discussed.The results show that the bistability of the adjustable bump surface requires a certain boundary constraint and geometric parameter combination,and that there are local and overall snap-through phenomena during transition which are related to the loading position and structural parameters.Therefore,suitable loading position and structural material could reduce input energy and meet the demand of structural strain.
文摘Three-dimensional(3D)Stokes flow of an incompressible fluid in a curved channel is analyzed.The flow field and characteristics under the influence of 3D surface bumps are studied.A mathematical model describing the 3D complex flow in the curvilinear geometry is formulated and validated.The solution of the coupled system of quasilinear partial differential equations associated with the model is obtained analytically.The behavior of the velocity distribution as the fluid moves through the undulating passage of the bumpy curved channel is examined and explained for each velocity component.The analysis of this flow problem indicates that the velocity vector of the flow is significantly altered by the presence of the structures on the bounding bumpy surfaces,depending on the alignment of the bumps.Furthermore,it is found that the difference between the flow rate in the bumpy curved channel and that in a smooth curved channel is essentially a function of the geometric characteristics of the surface bumps and the curved channel.Notably,the flow in a bumpy straight channel is a limiting case of that in the bumpy curved channel,but the overall effect of the bumps is more significant for a bumpy curved channel.
文摘The primary focus of the present survey is to categorize the results of various investigations on the Shock/Boundary-Layer Interactions(SBLIs),their repercussions,and the effective ways to control them.The interactions of shock waves with the boundary layer are an important area of research due to their ubiquity in several applications ranging from transonic to hypersonic flows.Therefore,there is a need for a detailed inspection to understand the phenomena to predict its characteristics with certain accuracy.Considering this in mind,this article presents some key features of the physical nature of SBLIs,their consequences,and the control techniques in a sequential manner;in particular,the passive control techniques for the supersonic and hypersonic intakes are reviewed in detail.
