Firstly, the steady laminar flow field of a hypersonic sharp cone boundary layer with zero angle of attack was computed. Then, two groups of finite amplitude T-S wave disturbances were introduced at the entrance of th...Firstly, the steady laminar flow field of a hypersonic sharp cone boundary layer with zero angle of attack was computed. Then, two groups of finite amplitude T-S wave disturbances were introduced at the entrance of the computational field, and the spatial mode transition process was studied by direct numerical simulation （DNS） method. The mechanism of the transition process was analyzed. It was found that the change of the stability characteristics of the mean flow profile was the key issue. Furthermore, the characteristics of evolution for the disturbances of different modes in the hypersonic sharp cone boundary layer were discussed.展开更多
感应耦合能量传输(inductively coupled power transfer,ICPT)系统中补偿网络能够改善系统特性,目前针对谐振补偿网络的输出电流和电压特性没有一种简单易行的分析模型。首先分析了LC电路、??型电路和T型电路实现与负载无关的恒流或恒...感应耦合能量传输(inductively coupled power transfer,ICPT)系统中补偿网络能够改善系统特性,目前针对谐振补偿网络的输出电流和电压特性没有一种简单易行的分析模型。首先分析了LC电路、??型电路和T型电路实现与负载无关的恒流或恒压输出的谐振条件,并针对高阶无源谐振网络提出一种建模方法,通过将谐振网络等效成2阶LC网络和多级3阶???型电路或多级3阶T型电路的串联,研究其恒流或恒压输出的物理机理。ICPT系统中双边LCC谐振腔实质上是一个9阶谐振网络,基于所提建模方法,分析双边LCC谐振腔输出电流和电压特性。此外,提出仅切换一次系统工作频率便可以实现系统先恒流再恒压输出的方法,且恒流和恒压模式下系统工作频率均满足SAEJ2954标准要求,分别能实现谐振腔输入电压、电流之间的零相角和原边逆变器MOSFETs的零电压开通。搭建3.3kW电动汽车感应耦合能量传输系统的Matlab仿真平台和实验样机,验证理论分析的正确性和可行性。恒流和恒压模式下实验样机谐振腔的效率分别为92.1%和89.7%。展开更多
基金Project supported by the National Natural Science Foundation of China (Key Program) (No.10632050)
文摘Firstly, the steady laminar flow field of a hypersonic sharp cone boundary layer with zero angle of attack was computed. Then, two groups of finite amplitude T-S wave disturbances were introduced at the entrance of the computational field, and the spatial mode transition process was studied by direct numerical simulation （DNS） method. The mechanism of the transition process was analyzed. It was found that the change of the stability characteristics of the mean flow profile was the key issue. Furthermore, the characteristics of evolution for the disturbances of different modes in the hypersonic sharp cone boundary layer were discussed.
文摘感应耦合能量传输(inductively coupled power transfer,ICPT)系统中补偿网络能够改善系统特性,目前针对谐振补偿网络的输出电流和电压特性没有一种简单易行的分析模型。首先分析了LC电路、??型电路和T型电路实现与负载无关的恒流或恒压输出的谐振条件,并针对高阶无源谐振网络提出一种建模方法,通过将谐振网络等效成2阶LC网络和多级3阶???型电路或多级3阶T型电路的串联,研究其恒流或恒压输出的物理机理。ICPT系统中双边LCC谐振腔实质上是一个9阶谐振网络,基于所提建模方法,分析双边LCC谐振腔输出电流和电压特性。此外,提出仅切换一次系统工作频率便可以实现系统先恒流再恒压输出的方法,且恒流和恒压模式下系统工作频率均满足SAEJ2954标准要求,分别能实现谐振腔输入电压、电流之间的零相角和原边逆变器MOSFETs的零电压开通。搭建3.3kW电动汽车感应耦合能量传输系统的Matlab仿真平台和实验样机,验证理论分析的正确性和可行性。恒流和恒压模式下实验样机谐振腔的效率分别为92.1%和89.7%。
