A two-dimensional finite element(FE)model for the high speed turning operations when orthogonally machining AISI H13 tool steel at 49HRC using poly crystalline cubic boron nitride(PCBN)is described.An arbitrary Lagran...A two-dimensional finite element(FE)model for the high speed turning operations when orthogonally machining AISI H13 tool steel at 49HRC using poly crystalline cubic boron nitride(PCBN)is described.An arbitrary Lagrangian Eulerian(ALE)method has been adopted which does not need any chip separation criteria as opposed to the traditional Lagrangian approach.Through FE simulations temperature and stresses distributions are presented that could be helpful in predicting tool life and improving process parameters.The results show that high temperatures are generated along the tool rake face as compared to the shear zone temperatures due to high thermal conductivity of PCBN tools.展开更多
Extensive numerical investigations of the performance and flow structure in an unshrouded tandem-bladed centrifugal compressor are presented in comparison to a conventional compressor.Stage characteristics are explore...Extensive numerical investigations of the performance and flow structure in an unshrouded tandem-bladed centrifugal compressor are presented in comparison to a conventional compressor.Stage characteristics are explored for various tip clearance levels,axial spacings and circumferential clockings.Conventional impeller was modified to tandem-bladed design with no modifications in backsweep angle,meridional gas passage and camber distributions in order to have a true comparison with conventional design.Performance degradation is observed for both the conventional and tandem designs with increase in tip clearance.Linear-equation models for correlating stage characteristics with tip clearance are proposed.Comparing two designs,it is clearly evident that the conventional design shows better performance at moderate flow rates.However;near choke flow,tandem design gives better results primarily because of the increase in throat area.Surge point flow rate also seems to drop for tandem compressor resulting in increased range of operation.展开更多
基金This project is supported by National Natural Science Foundation of China(No.50505003).
文摘A two-dimensional finite element(FE)model for the high speed turning operations when orthogonally machining AISI H13 tool steel at 49HRC using poly crystalline cubic boron nitride(PCBN)is described.An arbitrary Lagrangian Eulerian(ALE)method has been adopted which does not need any chip separation criteria as opposed to the traditional Lagrangian approach.Through FE simulations temperature and stresses distributions are presented that could be helpful in predicting tool life and improving process parameters.The results show that high temperatures are generated along the tool rake face as compared to the shear zone temperatures due to high thermal conductivity of PCBN tools.
基金the Deanship of Scientific Research,Research Center of College of Engineering, King Saud University for the financial support
文摘Extensive numerical investigations of the performance and flow structure in an unshrouded tandem-bladed centrifugal compressor are presented in comparison to a conventional compressor.Stage characteristics are explored for various tip clearance levels,axial spacings and circumferential clockings.Conventional impeller was modified to tandem-bladed design with no modifications in backsweep angle,meridional gas passage and camber distributions in order to have a true comparison with conventional design.Performance degradation is observed for both the conventional and tandem designs with increase in tip clearance.Linear-equation models for correlating stage characteristics with tip clearance are proposed.Comparing two designs,it is clearly evident that the conventional design shows better performance at moderate flow rates.However;near choke flow,tandem design gives better results primarily because of the increase in throat area.Surge point flow rate also seems to drop for tandem compressor resulting in increased range of operation.
