An impeller is the most important component affecting the performance of centrifugal fans. The flow in the impeller is very complicated, and the 3\|D viscous flow is difficult to simulate numerically. This paper prese...An impeller is the most important component affecting the performance of centrifugal fans. The flow in the impeller is very complicated, and the 3\|D viscous flow is difficult to simulate numerically. This paper presents a numerical method for simulating the flow in practical commercial impellers. The predictions are compared with experimentally measured fan performance results. The predicted total pressure and efficiency for two fan models, whose optimum designs were determined by this method, agree well with the measured data for the design flow rate. The results show that the aerodynamic and noise levels for these two models are excellent. The paper also presents several new ideas about the shape of the front plate and the blade flow pattern to improve the flow in an impeller channel. The practical simulation methodology and results developed here will be very useful to the fan industry in the future.展开更多
This paper presents an aerodynamic design of a small transonic fan by 3D viscous RNS solver combined with genetic algorithms.The aerodynamic design system based on the 3D viscous RNS solver reduces the dependency on t...This paper presents an aerodynamic design of a small transonic fan by 3D viscous RNS solver combined with genetic algorithms.The aerodynamic design system based on the 3D viscous RNS solver reduces the dependency on the design experience for designers.Furthermore the optimum with genetic algorithms is an effective method for improving the transonic fan performance as a part of the design system.The design result showed that the transonic fan designed by this method reaches the design requirement even with more efficiency value.展开更多
A theoretical calculation method of off-design performance is developed for an axial flow fan of oil cooling system in helicopter,including calculation of aerodynamic parameters and performance parameters.When calcula...A theoretical calculation method of off-design performance is developed for an axial flow fan of oil cooling system in helicopter,including calculation of aerodynamic parameters and performance parameters.When calculating inlet shock loss,the shock loss coefficient is obtained by comparing results of theoretical calculation,experimental and numerical calculation.The theoretical results and numerical results show that all air velocity components increase from hub to shroud in main flow area at rated condition.Tip leakage vortex moves downstream as flow rate increases.When flow rate decreases,Re decreases,and boundary layer thickness from hub to shroud area all increases gradually.Tip leakage vortex moves upstream,and secondary loss increases.Low speed area in the passage is widened along with high speed area moving to hub area,influenced by boundary layer separation.Consequently wake area and jet area at fan outlet are both larger than rated condition.Therefore optimization design for off-design performance of the fan is required on aerodynamic parameters influencing fan loss.A reliable method is supplied for estimating altitude performance of lubricating system in helicopter.展开更多
Non-dimensional design concept for FOD tolerant fan blades is introduced based on the analyses of simplified impact models. The fan blades arc idealized as either beams or plates of elastic or rigid-plastic materials....Non-dimensional design concept for FOD tolerant fan blades is introduced based on the analyses of simplified impact models. The fan blades arc idealized as either beams or plates of elastic or rigid-plastic materials. The case of constant force impact as well as that of mass impact is analyzed. The centrifugal force effects are also considered in the beam models. The critical fracture conditions arc shown in simple npn-dimensional formulae or diagrams for each case.展开更多
文摘An impeller is the most important component affecting the performance of centrifugal fans. The flow in the impeller is very complicated, and the 3\|D viscous flow is difficult to simulate numerically. This paper presents a numerical method for simulating the flow in practical commercial impellers. The predictions are compared with experimentally measured fan performance results. The predicted total pressure and efficiency for two fan models, whose optimum designs were determined by this method, agree well with the measured data for the design flow rate. The results show that the aerodynamic and noise levels for these two models are excellent. The paper also presents several new ideas about the shape of the front plate and the blade flow pattern to improve the flow in an impeller channel. The practical simulation methodology and results developed here will be very useful to the fan industry in the future.
基金Sponsored by the Major State Basic Research Development Progrma of China(Grant No. 2007CB210104)
文摘This paper presents an aerodynamic design of a small transonic fan by 3D viscous RNS solver combined with genetic algorithms.The aerodynamic design system based on the 3D viscous RNS solver reduces the dependency on the design experience for designers.Furthermore the optimum with genetic algorithms is an effective method for improving the transonic fan performance as a part of the design system.The design result showed that the transonic fan designed by this method reaches the design requirement even with more efficiency value.
基金National Aviation Science Foundation of China (No. 20080451014)
文摘A theoretical calculation method of off-design performance is developed for an axial flow fan of oil cooling system in helicopter,including calculation of aerodynamic parameters and performance parameters.When calculating inlet shock loss,the shock loss coefficient is obtained by comparing results of theoretical calculation,experimental and numerical calculation.The theoretical results and numerical results show that all air velocity components increase from hub to shroud in main flow area at rated condition.Tip leakage vortex moves downstream as flow rate increases.When flow rate decreases,Re decreases,and boundary layer thickness from hub to shroud area all increases gradually.Tip leakage vortex moves upstream,and secondary loss increases.Low speed area in the passage is widened along with high speed area moving to hub area,influenced by boundary layer separation.Consequently wake area and jet area at fan outlet are both larger than rated condition.Therefore optimization design for off-design performance of the fan is required on aerodynamic parameters influencing fan loss.A reliable method is supplied for estimating altitude performance of lubricating system in helicopter.
文摘Non-dimensional design concept for FOD tolerant fan blades is introduced based on the analyses of simplified impact models. The fan blades arc idealized as either beams or plates of elastic or rigid-plastic materials. The case of constant force impact as well as that of mass impact is analyzed. The centrifugal force effects are also considered in the beam models. The critical fracture conditions arc shown in simple npn-dimensional formulae or diagrams for each case.
