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
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
The volute tongue can split the gas in the multi-blade centrifugal fan to make the gas flow to the volute outlet as much as possible.However,the unsteady axial deflection of the gas in the impeller results in differen...The volute tongue can split the gas in the multi-blade centrifugal fan to make the gas flow to the volute outlet as much as possible.However,the unsteady axial deflection of the gas in the impeller results in different air flow angles at the outlet of the impeller at different blade heights.This seriously affects the flow near the volute tongue.The wave leading-edge structure of humpback whale flippers has a very high flow control effect under complex flow conditions.Therefore,the wave leading-edge structure is studied in this paper and applied to the optimization design of multi-blade centrifugal fan volute tongue.First,based on the wave leading-edge structure of humpback whale flippers,three-dimensional wave leading-edge airfoils with different wave direction angles are established to judge the adaptability of the new wave leading-edge structure under different attack angles.Then,aiming at the internal flow field and noise characteristics of multi-blade centrifugal fan,a bionic volute tongue optimization design method is proposed,and studied its influence on the internal flow field and noise characteristics of the fan.The results show that when the wave direction angle is 45°,the wave leading-edge structure can effectively suppress the generation of the leading-edge separation vortex and the shedding of the wake vortex,which is also helpful to reduce the noise.The bionic volute tongue with the wave leading-edge structure can adapt to the situation that the impeller outlet air flow angle is small.At the maximum volume flow rate operating point,the static pressure recovery coefficient of the bionic volute tongue fan is increased by about 5%compared to the original fan,the air volume is increased by 5.16%,and the noise is reduced by 0.6 dB.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
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.
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.
基金supported by the National Natural Science Foundation of China(11872289)“Aviation Engines and Gas Turbines”National Science and Technology Major Project Funding(J2019-IV-005-0072).
文摘The volute tongue can split the gas in the multi-blade centrifugal fan to make the gas flow to the volute outlet as much as possible.However,the unsteady axial deflection of the gas in the impeller results in different air flow angles at the outlet of the impeller at different blade heights.This seriously affects the flow near the volute tongue.The wave leading-edge structure of humpback whale flippers has a very high flow control effect under complex flow conditions.Therefore,the wave leading-edge structure is studied in this paper and applied to the optimization design of multi-blade centrifugal fan volute tongue.First,based on the wave leading-edge structure of humpback whale flippers,three-dimensional wave leading-edge airfoils with different wave direction angles are established to judge the adaptability of the new wave leading-edge structure under different attack angles.Then,aiming at the internal flow field and noise characteristics of multi-blade centrifugal fan,a bionic volute tongue optimization design method is proposed,and studied its influence on the internal flow field and noise characteristics of the fan.The results show that when the wave direction angle is 45°,the wave leading-edge structure can effectively suppress the generation of the leading-edge separation vortex and the shedding of the wake vortex,which is also helpful to reduce the noise.The bionic volute tongue with the wave leading-edge structure can adapt to the situation that the impeller outlet air flow angle is small.At the maximum volume flow rate operating point,the static pressure recovery coefficient of the bionic volute tongue fan is increased by about 5%compared to the original fan,the air volume is increased by 5.16%,and the noise is reduced by 0.6 dB.
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.