The automobile engine pump is an important part of the automobile cooling system,and has a direct influence on the engine performance.Based on the SST k-ωturbulence model,unsteady numerical simulation for an automobi...The automobile engine pump is an important part of the automobile cooling system,and has a direct influence on the engine performance.Based on the SST k-ωturbulence model,unsteady numerical simulation for an automobile engine pump with different tip clearances was carried out by Fluent.To study the flow field characteristics and pressure fluctuation,the characteristics of secondary flow distribution in volute are also analyzed.The result shows that the pressure fluctuation characteristics of the flow field show obvious periodic variation at different levels of tip clearances.The peak value of pressure fluctuation at each monitoring point is dependent on the blade frequency.At the same time,with the increase of the tip clearance,the pressure fluctuation in the blade and volute is gradually increased,while the pressure fluctuation at the tip is reduced clearance.The pressure gradient in the pump also varies periodically with the rotation of the impeller.With the increase of the tip clearance,the pressure of the impeller,volute and tip clearance is gradually decreased.There are secondary flow vortexes inside the impeller,volute outlet and volute section.With the increase of tip clearance,the vortex intensity in the impeller channel is weakened,and the vortex strength at the volute outlet is intensified.On the cross section of the volute,the morphology of most vortexes has insignificant changes,but the vortex intensity decreased.展开更多
Computational Fluid Dynamics is used to assess the thermal(heat transfer)performances of an automobile engine considering different grille opening and closing degrees.For this purpose the entire vehicle is modelled an...Computational Fluid Dynamics is used to assess the thermal(heat transfer)performances of an automobile engine considering different grille opening and closing degrees.For this purpose the entire vehicle is modelled and three fundamental aspects are examined,namely,the open area of the air intake grille,the position of the upper and lower grilles and their shape.The results show that the opening area and position of the grille have some influence also on the aerodynamic characteristics of the automobile.With an increase in the opening angle of the grille,the CD(Drag Coefficient)value of the whole vehicle becomes higher.When the air intake grille of the car is fully open or closed,the CD value is 0.35434 or 0.31777,respectively,that is,the flow resistance in the engine compartment accounts for 10.32%of the CD value for the whole automobile.展开更多
To improve the braking safety of automobiles, the author studied the effect of differential brake on the stabilities. To analyze the mechanical characteristics of differential brake, automotive subsystem models were b...To improve the braking safety of automobiles, the author studied the effect of differential brake on the stabilities. To analyze the mechanical characteristics of differential brake, automotive subsystem models were built by applying ADAMS/CAR, and automotive mechanics simulation model was built by setting the main subsystems such as body, engine and brake. The simulation model studied the distribution mode of three kinds of differential brake, and beeline braking stability and turning braking stability were simulated. It shows that differential brake can amend turning shortage of automobile brake and improve its braking stability, but the effect of automobile mass on its braking stability is great. So the distribution mode of braking force and the effect of mass change should be considered while differential brake is applied.展开更多
This paper uses the minimization and weighted sum of battery capacity loss and energy consumption under driving cycles as objective functions to improve the economy of Electric Vehicles(EVs)with an hybrid energy stora...This paper uses the minimization and weighted sum of battery capacity loss and energy consumption under driving cycles as objective functions to improve the economy of Electric Vehicles(EVs)with an hybrid energy storage system composed of power batteries and ultracapacitors.Furthermore,Dynamic Programming(DP)is employed to determine the objective function values under different weight coefficients,the comprehensive cost consisting of battery aging and power consumption costs,and the relationship between the hybrid power distribution.We also evaluate the real-time fuzzy Energy Management Strategy(EMS),fuzzy control strategies,and a strategy based on DP using the World Light vehicle Test Procedure(WLTP)driving cycle and a synthesis driving cycle derived from New European Driving Cycle(NEDC),WLTP,and Urban Dynamometer Driving Schedule(UDDS)as examples.Then,the proposed strategy is compared with the fuzzy control strategy and the strategy based on DP.Compared with fuzzy energy management strategy(namely FZY-EMS),the proposed EMS reduces the battery capacity loss and system energy consumption.The results demonstrate the effectiveness of the proposed EMS in improving EV economy.展开更多
Increasing energy consumption in the transportation sector results in challenging greenhouse gas(GHG)emissions and environmental problems.This paper involved integrated assessments on GHG emissions and emergy of the l...Increasing energy consumption in the transportation sector results in challenging greenhouse gas(GHG)emissions and environmental problems.This paper involved integrated assessments on GHG emissions and emergy of the life cycle for the internal combustion engine(ICE)and electric automobiles in the USA over the entire assumed fifteen-year lifetime.The hotspots of GHG emissions as well as emergy indices for the major processes of automobile life cycle within the defined system boundaries have been investigated.The potential strategies for reducing GHG emissions and emergy in the life cycle of both ICE and electric automobiles were further proposed.Based on the current results,the total GHG emissions from the life cycle of ICE automobiles are 4.48 E+07 kg CO2-e which is320 times higher than that of the electric automobiles.The hotspot area of the GHG emissions from ICE and electric automobiles are operation phase and manufacturing process,respectively.Interesting results were observed that comparable total emergy of the ICE automobiles and electric automobiles have been calculated which were 1.54 E+17 and 2.20 E+17 sej,respectively.Analysis on emergy index evidenced a better environmental sustainability of electric automobiles than ICE automobiles over the life cycle due to its higher ESI.To the authors’knowledge,it is the first time to integrate the analysis of GHG emissions together with emergy in industrial area of automobile engineering.It is expected that the integration of emergy and GHG emissions analysis may provide a comprehensive perspective on eco-industrial sustainability of automobile engineering.展开更多
基金The authors gratefully acknowledge the financial supports given by the National Nature Science Foundation of China(51709234).
文摘The automobile engine pump is an important part of the automobile cooling system,and has a direct influence on the engine performance.Based on the SST k-ωturbulence model,unsteady numerical simulation for an automobile engine pump with different tip clearances was carried out by Fluent.To study the flow field characteristics and pressure fluctuation,the characteristics of secondary flow distribution in volute are also analyzed.The result shows that the pressure fluctuation characteristics of the flow field show obvious periodic variation at different levels of tip clearances.The peak value of pressure fluctuation at each monitoring point is dependent on the blade frequency.At the same time,with the increase of the tip clearance,the pressure fluctuation in the blade and volute is gradually increased,while the pressure fluctuation at the tip is reduced clearance.The pressure gradient in the pump also varies periodically with the rotation of the impeller.With the increase of the tip clearance,the pressure of the impeller,volute and tip clearance is gradually decreased.There are secondary flow vortexes inside the impeller,volute outlet and volute section.With the increase of tip clearance,the vortex intensity in the impeller channel is weakened,and the vortex strength at the volute outlet is intensified.On the cross section of the volute,the morphology of most vortexes has insignificant changes,but the vortex intensity decreased.
文摘Computational Fluid Dynamics is used to assess the thermal(heat transfer)performances of an automobile engine considering different grille opening and closing degrees.For this purpose the entire vehicle is modelled and three fundamental aspects are examined,namely,the open area of the air intake grille,the position of the upper and lower grilles and their shape.The results show that the opening area and position of the grille have some influence also on the aerodynamic characteristics of the automobile.With an increase in the opening angle of the grille,the CD(Drag Coefficient)value of the whole vehicle becomes higher.When the air intake grille of the car is fully open or closed,the CD value is 0.35434 or 0.31777,respectively,that is,the flow resistance in the engine compartment accounts for 10.32%of the CD value for the whole automobile.
基金Western Countries,Traffic IT Projects Traffic (No.200431800048)
文摘To improve the braking safety of automobiles, the author studied the effect of differential brake on the stabilities. To analyze the mechanical characteristics of differential brake, automotive subsystem models were built by applying ADAMS/CAR, and automotive mechanics simulation model was built by setting the main subsystems such as body, engine and brake. The simulation model studied the distribution mode of three kinds of differential brake, and beeline braking stability and turning braking stability were simulated. It shows that differential brake can amend turning shortage of automobile brake and improve its braking stability, but the effect of automobile mass on its braking stability is great. So the distribution mode of braking force and the effect of mass change should be considered while differential brake is applied.
基金supported by the National Key Research and Development Program of China(No.2020YFB1600400)the Scientific Research Project of the Department of Transport of Shaanxi Province(No.18-27R).
文摘This paper uses the minimization and weighted sum of battery capacity loss and energy consumption under driving cycles as objective functions to improve the economy of Electric Vehicles(EVs)with an hybrid energy storage system composed of power batteries and ultracapacitors.Furthermore,Dynamic Programming(DP)is employed to determine the objective function values under different weight coefficients,the comprehensive cost consisting of battery aging and power consumption costs,and the relationship between the hybrid power distribution.We also evaluate the real-time fuzzy Energy Management Strategy(EMS),fuzzy control strategies,and a strategy based on DP using the World Light vehicle Test Procedure(WLTP)driving cycle and a synthesis driving cycle derived from New European Driving Cycle(NEDC),WLTP,and Urban Dynamometer Driving Schedule(UDDS)as examples.Then,the proposed strategy is compared with the fuzzy control strategy and the strategy based on DP.Compared with fuzzy energy management strategy(namely FZY-EMS),the proposed EMS reduces the battery capacity loss and system energy consumption.The results demonstrate the effectiveness of the proposed EMS in improving EV economy.
基金financially supported by National Natural Science Foundation for Young Scientists of China(Grant No.51608531)
文摘Increasing energy consumption in the transportation sector results in challenging greenhouse gas(GHG)emissions and environmental problems.This paper involved integrated assessments on GHG emissions and emergy of the life cycle for the internal combustion engine(ICE)and electric automobiles in the USA over the entire assumed fifteen-year lifetime.The hotspots of GHG emissions as well as emergy indices for the major processes of automobile life cycle within the defined system boundaries have been investigated.The potential strategies for reducing GHG emissions and emergy in the life cycle of both ICE and electric automobiles were further proposed.Based on the current results,the total GHG emissions from the life cycle of ICE automobiles are 4.48 E+07 kg CO2-e which is320 times higher than that of the electric automobiles.The hotspot area of the GHG emissions from ICE and electric automobiles are operation phase and manufacturing process,respectively.Interesting results were observed that comparable total emergy of the ICE automobiles and electric automobiles have been calculated which were 1.54 E+17 and 2.20 E+17 sej,respectively.Analysis on emergy index evidenced a better environmental sustainability of electric automobiles than ICE automobiles over the life cycle due to its higher ESI.To the authors’knowledge,it is the first time to integrate the analysis of GHG emissions together with emergy in industrial area of automobile engineering.It is expected that the integration of emergy and GHG emissions analysis may provide a comprehensive perspective on eco-industrial sustainability of automobile engineering.