Aerodynamic performances of axial compressors are significantly affected by variation of Reynolds number in aero-engines.In the design and analysis of compressors,previous correction methods for cascades and stages ha...Aerodynamic performances of axial compressors are significantly affected by variation of Reynolds number in aero-engines.In the design and analysis of compressors,previous correction methods for cascades and stages have difficulties in predicting comprehensively Reynolds number effects on airfoils,matching and characteristics curves.This study proposes Re-correction models for loss,deviation angle and endwall blockage based on classical theories and cascade tests,and loss and deviation models show good agreement in test data of NACA65 and C4 cascades.Throughflow method considering Reynolds number effects is developed by integrating the correction models into a verified Streamline Curvature(SLC)tool.A three-stage axial compressor is investigated through SLC and CFD methods from design Reynolds number(Red=2106)to low Re=4104,and the numerical methods are validated with test data of characteristic curves and spanwise distributions at Red.With Re reduction,SLC method with correction models well predicts variation in overall performances compared with CFD calculations and Wassell's model.Streamwise and spanwise matching such as total pressure and loss distributions in SLC predictions are basically consistent with those in CFD results at near-stall points under design and low Reynolds numbers.SLC and CFD methods share similar detections of stall risks in the third stage(Stg3),and their analyses of diffusion processes deviate to some extent due to different predictions in separated endwall flow.The correction models can be adopted to consider Reynolds number effects in through-flow design and analysis of axial compressors.展开更多
In this study,the capability of deep neural network is verified in the aerodynamic design of supersonic through-flow fan blade profile.A highly flexible parameterization method was first proposed,followed by generatin...In this study,the capability of deep neural network is verified in the aerodynamic design of supersonic through-flow fan blade profile.A highly flexible parameterization method was first proposed,followed by generating a flow field data set using Latin Hypercube Sampling and batch processing.Through flexible deep neural network architectures,positive designs of prediction on performance,static pressure distribution and flow field from design variables,and the inverse design from static pressure distribution to blade profile,were well achieved.The effects of different deep neural network architectures on prediction performance are systematically compared,and the inverse design accuracy is quantitatively evaluated using representative error metrics.Moreover,this study provides comparisons of prediction accuracy among different architectures,sample sizes,physical complexities,and treatment approaches,with detailed assessments for each neural network.It was found that the deep neural network is powerful for establishing the physical relationship between input and output parameters in aerodynamic design,supporting flexible input-output combinations while ensuring a certain level of prediction accuracy.However,caution is advised during the later stage of design,as the prediction error is hard to be totally eliminated.Additionally,regions with drastic changes and boundaries of the design space tend to have larger prediction error.展开更多
The through-flow analysis is an important part in the compressor design process.In this part,lots of empirical models are used to predict the compressor aerodynamic performances.These models are all based on the early...The through-flow analysis is an important part in the compressor design process.In this part,lots of empirical models are used to predict the compressor aerodynamic performances.These models are all based on the early experimental results of low-load and low-speed compressors;so,they may not be suitable for modern compressor performance estimations.In this study,several empirical models were reviewed,and two new models to estimate the minimum blade profile loss and minimum-loss deviation angle were established using mathematical statistics.Then,the original models with poor accuracy were replaced by these two models in through-flow program.Next,three compressors(Rotor 67,Stage 35,and a 4-stage repeating stage)were simulated using both the original and new models.The final results show that the new models have better accuracy in estimating the performance parameters than the original models.This indicates that it is feasible to use mathematical statistical methods to establish the empirical models,and this method provides an idea for the improvement of other empirical models in through-flow program.展开更多
The influence of complicated interaction between the flow field and heat transfer in cooled turbines becomes more and more significant with the increasing turbine inlet temperature. However, classical through-flow met...The influence of complicated interaction between the flow field and heat transfer in cooled turbines becomes more and more significant with the increasing turbine inlet temperature. However, classical through-flow methods did not take into account the influence of the interaction caused by air cooling. The aerodynamic design and cooling design of cooled turbines were carried out separately, and the iterations between the aerodynamic design and cooling design led to a long design period and raised the design cost. To shorten the design period and decrease the design cost, this paper proposes a concise aero-thermal coupled through-flow method for the design of cooled turbines, taking into account the influence of the complicated interaction between the flow field and heat transfer in cooled turbines. The governing equations, such as energy equation and continuity equation in classical through-flow method are re-derived theoretically by considering the historical influence of cooling with the same method that deals with viscous losses in this paper. A cooling model is developed in this method. The cooled blade is split into a number of heat transfer elements, and the heat transfer is studied element by element along both the span and the chord in detail. This paper applies the method in the design of a two-stage axial turbine, of which the first stator is cooled with convective cooling. With the prescribed blade temperature limitation and the knowledge of the flow variables of the mainstream at the turbine inlet, such as the total pressure, total temperature and mass flow rate, the convergence of the calculation is then obtained and the properties of the flow field, velocity triangles and coolant requirement are well predicted. The calculated results prove that the aero-thermal coupled through-flow method is a reliable tool for flow analysis and coolant requirement prediction in the design of cooled turbines.展开更多
Through-flow method is still widely applied in the revolution of the design of a turbomachinery, which can provide not merely the performance characteristic but also the flow field. In this study,a program based on th...Through-flow method is still widely applied in the revolution of the design of a turbomachinery, which can provide not merely the performance characteristic but also the flow field. In this study,a program based on the through-flow method was proposed, which had been verified by many other numerical examples. So as to improve the accuracy of the calculation, abundant loss and deviation models dependent on the real geometry of engine were put into use,such as: viscous losses,overflow in gaps, leakage from a flow path through seals. By means of this program, the aerodynamic performance of a certain high through-flow commercial fan/booster was investigated. On account of the radial distributions of the relevant parameters, flow deterioration in this machine was speculated. To confirm this surmise, 3-D numerical simulation was carried out with the help of the NUMECA software. Through detailed analysis, the speculation above was demonstrated, which provide sufficient evidence for the conclusion that the through-flow method is an essential and effective method for the performance prediction of the fan/booster.展开更多
电化学消毒因其装置小巧、安全高效和易于管理等特点,特别适用于农村地区分散式供水系统.采用浸渍法制备出四氧化三铁纳米颗粒-碳毡(Fe3O4NPs-CF)复合电极,并对复合电极的形貌和电化学性能等进行了表征.同时构建穿流式电化学消毒装置,...电化学消毒因其装置小巧、安全高效和易于管理等特点,特别适用于农村地区分散式供水系统.采用浸渍法制备出四氧化三铁纳米颗粒-碳毡(Fe3O4NPs-CF)复合电极,并对复合电极的形貌和电化学性能等进行了表征.同时构建穿流式电化学消毒装置,以大肠杆菌为消毒对象,通过单因素试验探究了Fe3O4NPs负载量、电流密度和流量对消毒性能的影响,并进一步分析了其消毒机理.结果表明,Fe3O4NPs-CF具有良好的负载稳定性和导电性,在负载量为0.3 g,电流密度为120 m A·cm^(-2),流量为3 m L·min^(-1)条件下,即可对10~5 CFU·m·L-1的大肠杆菌菌液实现约5.0 log的灭活.消毒机理的探究结果表明,活性氧和活性氯对细菌灭活的作用有限,电场直接作用为细菌致死的主要原因.本研究为高效低耗的点用式饮用水消毒的研发和推广应用提供了科学依据.展开更多
基金supported by the National Science and Tech-nology Major Project of China(Nos.2017-II-0007-0021 and J2019-II-0017-0038)。
文摘Aerodynamic performances of axial compressors are significantly affected by variation of Reynolds number in aero-engines.In the design and analysis of compressors,previous correction methods for cascades and stages have difficulties in predicting comprehensively Reynolds number effects on airfoils,matching and characteristics curves.This study proposes Re-correction models for loss,deviation angle and endwall blockage based on classical theories and cascade tests,and loss and deviation models show good agreement in test data of NACA65 and C4 cascades.Throughflow method considering Reynolds number effects is developed by integrating the correction models into a verified Streamline Curvature(SLC)tool.A three-stage axial compressor is investigated through SLC and CFD methods from design Reynolds number(Red=2106)to low Re=4104,and the numerical methods are validated with test data of characteristic curves and spanwise distributions at Red.With Re reduction,SLC method with correction models well predicts variation in overall performances compared with CFD calculations and Wassell's model.Streamwise and spanwise matching such as total pressure and loss distributions in SLC predictions are basically consistent with those in CFD results at near-stall points under design and low Reynolds numbers.SLC and CFD methods share similar detections of stall risks in the third stage(Stg3),and their analyses of diffusion processes deviate to some extent due to different predictions in separated endwall flow.The correction models can be adopted to consider Reynolds number effects in through-flow design and analysis of axial compressors.
文摘In this study,the capability of deep neural network is verified in the aerodynamic design of supersonic through-flow fan blade profile.A highly flexible parameterization method was first proposed,followed by generating a flow field data set using Latin Hypercube Sampling and batch processing.Through flexible deep neural network architectures,positive designs of prediction on performance,static pressure distribution and flow field from design variables,and the inverse design from static pressure distribution to blade profile,were well achieved.The effects of different deep neural network architectures on prediction performance are systematically compared,and the inverse design accuracy is quantitatively evaluated using representative error metrics.Moreover,this study provides comparisons of prediction accuracy among different architectures,sample sizes,physical complexities,and treatment approaches,with detailed assessments for each neural network.It was found that the deep neural network is powerful for establishing the physical relationship between input and output parameters in aerodynamic design,supporting flexible input-output combinations while ensuring a certain level of prediction accuracy.However,caution is advised during the later stage of design,as the prediction error is hard to be totally eliminated.Additionally,regions with drastic changes and boundaries of the design space tend to have larger prediction error.
基金the National Natural Science Foundation of China for funding this work(Grant No.51676015).
文摘The through-flow analysis is an important part in the compressor design process.In this part,lots of empirical models are used to predict the compressor aerodynamic performances.These models are all based on the early experimental results of low-load and low-speed compressors;so,they may not be suitable for modern compressor performance estimations.In this study,several empirical models were reviewed,and two new models to estimate the minimum blade profile loss and minimum-loss deviation angle were established using mathematical statistics.Then,the original models with poor accuracy were replaced by these two models in through-flow program.Next,three compressors(Rotor 67,Stage 35,and a 4-stage repeating stage)were simulated using both the original and new models.The final results show that the new models have better accuracy in estimating the performance parameters than the original models.This indicates that it is feasible to use mathematical statistical methods to establish the empirical models,and this method provides an idea for the improvement of other empirical models in through-flow program.
基金supported by the National Natural Science Foundation of China(Grant No.51276093)
文摘The influence of complicated interaction between the flow field and heat transfer in cooled turbines becomes more and more significant with the increasing turbine inlet temperature. However, classical through-flow methods did not take into account the influence of the interaction caused by air cooling. The aerodynamic design and cooling design of cooled turbines were carried out separately, and the iterations between the aerodynamic design and cooling design led to a long design period and raised the design cost. To shorten the design period and decrease the design cost, this paper proposes a concise aero-thermal coupled through-flow method for the design of cooled turbines, taking into account the influence of the complicated interaction between the flow field and heat transfer in cooled turbines. The governing equations, such as energy equation and continuity equation in classical through-flow method are re-derived theoretically by considering the historical influence of cooling with the same method that deals with viscous losses in this paper. A cooling model is developed in this method. The cooled blade is split into a number of heat transfer elements, and the heat transfer is studied element by element along both the span and the chord in detail. This paper applies the method in the design of a two-stage axial turbine, of which the first stator is cooled with convective cooling. With the prescribed blade temperature limitation and the knowledge of the flow variables of the mainstream at the turbine inlet, such as the total pressure, total temperature and mass flow rate, the convergence of the calculation is then obtained and the properties of the flow field, velocity triangles and coolant requirement are well predicted. The calculated results prove that the aero-thermal coupled through-flow method is a reliable tool for flow analysis and coolant requirement prediction in the design of cooled turbines.
基金supported by National Natural Science Foundation of China(51236001)National Basic Research Program of China(2012CB720201)Beijing Natural Science Foundation(No.3151002)
文摘Through-flow method is still widely applied in the revolution of the design of a turbomachinery, which can provide not merely the performance characteristic but also the flow field. In this study,a program based on the through-flow method was proposed, which had been verified by many other numerical examples. So as to improve the accuracy of the calculation, abundant loss and deviation models dependent on the real geometry of engine were put into use,such as: viscous losses,overflow in gaps, leakage from a flow path through seals. By means of this program, the aerodynamic performance of a certain high through-flow commercial fan/booster was investigated. On account of the radial distributions of the relevant parameters, flow deterioration in this machine was speculated. To confirm this surmise, 3-D numerical simulation was carried out with the help of the NUMECA software. Through detailed analysis, the speculation above was demonstrated, which provide sufficient evidence for the conclusion that the through-flow method is an essential and effective method for the performance prediction of the fan/booster.
文摘电化学消毒因其装置小巧、安全高效和易于管理等特点,特别适用于农村地区分散式供水系统.采用浸渍法制备出四氧化三铁纳米颗粒-碳毡(Fe3O4NPs-CF)复合电极,并对复合电极的形貌和电化学性能等进行了表征.同时构建穿流式电化学消毒装置,以大肠杆菌为消毒对象,通过单因素试验探究了Fe3O4NPs负载量、电流密度和流量对消毒性能的影响,并进一步分析了其消毒机理.结果表明,Fe3O4NPs-CF具有良好的负载稳定性和导电性,在负载量为0.3 g,电流密度为120 m A·cm^(-2),流量为3 m L·min^(-1)条件下,即可对10~5 CFU·m·L-1的大肠杆菌菌液实现约5.0 log的灭活.消毒机理的探究结果表明,活性氧和活性氯对细菌灭活的作用有限,电场直接作用为细菌致死的主要原因.本研究为高效低耗的点用式饮用水消毒的研发和推广应用提供了科学依据.
