The shapes and geometrical parameters of nozzles are key factors for fluidics. The relationship among the reaction thrust, flow rate pressure, diameter do and length L of a cylinder nozzle is analyzed theoretically. T...The shapes and geometrical parameters of nozzles are key factors for fluidics. The relationship among the reaction thrust, flow rate pressure, diameter do and length L of a cylinder nozzle is analyzed theoretically. The simulation of the flow field characteristics was conducted via the FLUENT computational fluid dynamics package. Effects of the inlet conditions and the nozzle dimensions on the reaction thrust of a water jet were addressed particularly. The reaction thrust experiments were performed on a custom-designed test apparatus. The experimental results reveal that a） the nozzle diameter and the inlet conditions exert great influence on the water jet reaction thrust; and b） for L≤4d0, where the nozzle is treated as a thin plate-orifice, the reaction thrust is independent of nozzle length; for L〉4d0, where the nozzle is treated as a long orifice, the reaction thrust can reach maximum under the condition of a certain flow rate. These findings lay a theoretical foundation for the design of nozzles and have significant value, especially for the future development of high-oressure water-let orooulsion technology.展开更多
Based on the theory of moving surface boundary layer control(MSBC),a concept of an airfoil having a rotating cylinder at the leading edge has been developed and experimentally proven to have good aerodynamic performan...Based on the theory of moving surface boundary layer control(MSBC),a concept of an airfoil having a rotating cylinder at the leading edge has been developed and experimentally proven to have good aerodynamic performance even at large angles of attack.Thus,this research aims to give guidance on optimizing the design of this kind of airfoil with high lift coefficients.Using computational fluid dynamics(CFD)technique,the CFD simulation results have been compared with the experimental results available in the literature,and then the SST two-equation model is selected as the appropriate turbulence model.At a given cylinder surface velocity ratio,the cylinder diameter d,the drop height of trailing edgeδand the curvatures of the pressure and suction surfaces of the airfoil are regarded as the optimal design parameters and the airfoil lift coefficient is considered as the optimization objective function.Therefore,using orthogonal optimization method,we herein develop a new design of airfoil favorable for having a rotating leading edge.It has been numerically proven that the resulting airfoil has good capability of achieving a substantially superior performance when compared to the airfoils of the prior art.展开更多
基金Funded by the Natural Science Foundation of China (No. 50775081)the National High-tech R&D (863) Program No. 2006AA09Z238)the NCET-07-0330, State Education Ministry.
文摘The shapes and geometrical parameters of nozzles are key factors for fluidics. The relationship among the reaction thrust, flow rate pressure, diameter do and length L of a cylinder nozzle is analyzed theoretically. The simulation of the flow field characteristics was conducted via the FLUENT computational fluid dynamics package. Effects of the inlet conditions and the nozzle dimensions on the reaction thrust of a water jet were addressed particularly. The reaction thrust experiments were performed on a custom-designed test apparatus. The experimental results reveal that a） the nozzle diameter and the inlet conditions exert great influence on the water jet reaction thrust; and b） for L≤4d0, where the nozzle is treated as a thin plate-orifice, the reaction thrust is independent of nozzle length; for L〉4d0, where the nozzle is treated as a long orifice, the reaction thrust can reach maximum under the condition of a certain flow rate. These findings lay a theoretical foundation for the design of nozzles and have significant value, especially for the future development of high-oressure water-let orooulsion technology.
基金supported by National Natural Science Foundation of China(50836006)Shanghai Science and Technology Committee with Grant No.09JC1405800Program for Changjiang Scholars and Innovative Research Team in University with Grant No.IRT0844
文摘Based on the theory of moving surface boundary layer control(MSBC),a concept of an airfoil having a rotating cylinder at the leading edge has been developed and experimentally proven to have good aerodynamic performance even at large angles of attack.Thus,this research aims to give guidance on optimizing the design of this kind of airfoil with high lift coefficients.Using computational fluid dynamics(CFD)technique,the CFD simulation results have been compared with the experimental results available in the literature,and then the SST two-equation model is selected as the appropriate turbulence model.At a given cylinder surface velocity ratio,the cylinder diameter d,the drop height of trailing edgeδand the curvatures of the pressure and suction surfaces of the airfoil are regarded as the optimal design parameters and the airfoil lift coefficient is considered as the optimization objective function.Therefore,using orthogonal optimization method,we herein develop a new design of airfoil favorable for having a rotating leading edge.It has been numerically proven that the resulting airfoil has good capability of achieving a substantially superior performance when compared to the airfoils of the prior art.
