The self-induced unsteadiness in tip leakage flow(TLF)of a micro-axial fan rotor is numerically studied by solving Reynolds-averaged Navier-Stokes equations.The micro-axial fan,which is widely used in cooling systems ...The self-induced unsteadiness in tip leakage flow(TLF)of a micro-axial fan rotor is numerically studied by solving Reynolds-averaged Navier-Stokes equations.The micro-axial fan,which is widely used in cooling systems of electronic devices,has a tip clearance of 6%of the axial chord length of the blade.At the design rotation speed,four cases near the peak efficiency point(PEP)with self-induced unsteadiness and four steady cases which have much weaker pressure fluctuations are investigated.Using the"interface"separating the incoming main flow and the TLF defined by Duet al.[1],an explanation based on the propagation of the low energy spot and its multi-passing through the high gradient zone of the relative total pressure,is proposed to clarify the originating mechanism of the unsteadiness.At the operating points near the PEP,the main flow is weaker than the TLF and the interface moves upstream.The low energy spot which propagates along in the close behind of the interface has opportunity to circulate in the circumferential direction and passes through the sensitive interfaces several times,a slight perturbation therefore may be magnified significantly and develops into the self-induced unsteadiness.The explanation is demonstrated by numerical results.展开更多
定子槽漏感是定子无轭模块化(yokeless and segmented,YASA)轴向磁通永磁电机电感的主要分量,会降低电机的功率因数和最大输出转矩。该文提出定子槽内微小单元磁场能量法计算YASA电机的定子槽漏感,通过建立计及铁心饱和影响的二维等效...定子槽漏感是定子无轭模块化(yokeless and segmented,YASA)轴向磁通永磁电机电感的主要分量,会降低电机的功率因数和最大输出转矩。该文提出定子槽内微小单元磁场能量法计算YASA电机的定子槽漏感,通过建立计及铁心饱和影响的二维等效磁网络模型准确计算槽内微小单元储存的磁场能量,进而计算定子槽漏感。基于所提出的方法,进一步研究定子结构参数以及极槽配合对YASA电机定子槽漏感的影响规律。有限元仿真和实验结果表明,该文所提出的YASA电机定子槽漏感计算方法的可行性和准确性。展开更多
基金funded by the National Natural Science Foundation of China under Grant 50876031by Shanghai Municipal Education Commission under Grant 10ZZ40
文摘The self-induced unsteadiness in tip leakage flow(TLF)of a micro-axial fan rotor is numerically studied by solving Reynolds-averaged Navier-Stokes equations.The micro-axial fan,which is widely used in cooling systems of electronic devices,has a tip clearance of 6%of the axial chord length of the blade.At the design rotation speed,four cases near the peak efficiency point(PEP)with self-induced unsteadiness and four steady cases which have much weaker pressure fluctuations are investigated.Using the"interface"separating the incoming main flow and the TLF defined by Duet al.[1],an explanation based on the propagation of the low energy spot and its multi-passing through the high gradient zone of the relative total pressure,is proposed to clarify the originating mechanism of the unsteadiness.At the operating points near the PEP,the main flow is weaker than the TLF and the interface moves upstream.The low energy spot which propagates along in the close behind of the interface has opportunity to circulate in the circumferential direction and passes through the sensitive interfaces several times,a slight perturbation therefore may be magnified significantly and develops into the self-induced unsteadiness.The explanation is demonstrated by numerical results.
文摘定子槽漏感是定子无轭模块化(yokeless and segmented,YASA)轴向磁通永磁电机电感的主要分量,会降低电机的功率因数和最大输出转矩。该文提出定子槽内微小单元磁场能量法计算YASA电机的定子槽漏感,通过建立计及铁心饱和影响的二维等效磁网络模型准确计算槽内微小单元储存的磁场能量,进而计算定子槽漏感。基于所提出的方法,进一步研究定子结构参数以及极槽配合对YASA电机定子槽漏感的影响规律。有限元仿真和实验结果表明,该文所提出的YASA电机定子槽漏感计算方法的可行性和准确性。
