尽管以二阶精度格式为基础的计算流体力学(CFD)方法和软件已经在航空航天飞行器设计中发挥了重要的作用,但是由于二阶精度格式的耗散和色散较大,对于湍流、分离等多尺度流动现象的模拟,现有成熟的CFD软件仍难以给出满意的结果,为此CFD...尽管以二阶精度格式为基础的计算流体力学(CFD)方法和软件已经在航空航天飞行器设计中发挥了重要的作用,但是由于二阶精度格式的耗散和色散较大,对于湍流、分离等多尺度流动现象的模拟,现有成熟的CFD软件仍难以给出满意的结果,为此CFD工作者发展了众多的高阶精度计算格式.如果以适应的计算网格来分类,一般可以分为基于结构网格的有限差分格式、基于非结构/混合网格的有限体积法和有限元方法,以及各种类型的混合方法.由于非结构/混合网格具有良好的几何适应性,基于非结构/混合网格的高阶精度格式近年来备受关注.本文综述了近年来基于非结构/混合网格的高阶精度格式研究进展,重点介绍了空间离散方法,主要包括k-Exact和ENO/WENO等有限体积方法,间断伽辽金(DG)有限元方法,有限谱体积(SV)和有限谱差分(SD)方法,以及近来发展的各种DG/FV混合算法和将各种方法统一在一个框架内的CPR(correction procedure via reconstruction)方法等.随后简要介绍了高阶精度格式应用于复杂外形流动数值模拟的一些需要关注的问题,包括曲边界的处理方法、间断侦测和限制器、各种加速收敛技术等.在综述过程中,介绍了各种方法的优势与不足,其间介绍了作者发展的基于"静动态混合重构"的DG/FV混合算法.最后展望了基于非结构/混合网格的高阶精度格式的未来发展趋势及应用前景.展开更多
In this paper,a new hybrid excited doubly salient stator-permanent-magnet motor is proposed,where both permanent magnets and DC field windings are located in the stator.In theory,the mathematical model and design meth...In this paper,a new hybrid excited doubly salient stator-permanent-magnet motor is proposed,where both permanent magnets and DC field windings are located in the stator.In theory,the mathematical model and design method of the motor are developed.The corresponding output power equation and the relationship between the flux control capability and the extended speed range are deduced in details.By using an efficient "one-step" three-dimensional(3D) finite element method,the electromagnetic performances are analyzed,in which the leakage flux outside the stator circumference and end-effect are taken into account.Based on the operation principle of the motor,the control strategy and scheme are developed and implemented experimentally.Both experimental results and finite element analysis show that the proposed motor not only maintains the advantages of doubly salient permanent magnet motors,but also offers high energy efficiency over a wide speed range,which makes the motor an interesting candidate for electric vehicles.展开更多
文摘尽管以二阶精度格式为基础的计算流体力学(CFD)方法和软件已经在航空航天飞行器设计中发挥了重要的作用,但是由于二阶精度格式的耗散和色散较大,对于湍流、分离等多尺度流动现象的模拟,现有成熟的CFD软件仍难以给出满意的结果,为此CFD工作者发展了众多的高阶精度计算格式.如果以适应的计算网格来分类,一般可以分为基于结构网格的有限差分格式、基于非结构/混合网格的有限体积法和有限元方法,以及各种类型的混合方法.由于非结构/混合网格具有良好的几何适应性,基于非结构/混合网格的高阶精度格式近年来备受关注.本文综述了近年来基于非结构/混合网格的高阶精度格式研究进展,重点介绍了空间离散方法,主要包括k-Exact和ENO/WENO等有限体积方法,间断伽辽金(DG)有限元方法,有限谱体积(SV)和有限谱差分(SD)方法,以及近来发展的各种DG/FV混合算法和将各种方法统一在一个框架内的CPR(correction procedure via reconstruction)方法等.随后简要介绍了高阶精度格式应用于复杂外形流动数值模拟的一些需要关注的问题,包括曲边界的处理方法、间断侦测和限制器、各种加速收敛技术等.在综述过程中,介绍了各种方法的优势与不足,其间介绍了作者发展的基于"静动态混合重构"的DG/FV混合算法.最后展望了基于非结构/混合网格的高阶精度格式的未来发展趋势及应用前景.
基金supported by the National Natural Science Foundation of China (Grant Nos.50807022,50337030,50729702)the Foundation of Jiangsu University (Grant No.09JDG031)
文摘In this paper,a new hybrid excited doubly salient stator-permanent-magnet motor is proposed,where both permanent magnets and DC field windings are located in the stator.In theory,the mathematical model and design method of the motor are developed.The corresponding output power equation and the relationship between the flux control capability and the extended speed range are deduced in details.By using an efficient "one-step" three-dimensional(3D) finite element method,the electromagnetic performances are analyzed,in which the leakage flux outside the stator circumference and end-effect are taken into account.Based on the operation principle of the motor,the control strategy and scheme are developed and implemented experimentally.Both experimental results and finite element analysis show that the proposed motor not only maintains the advantages of doubly salient permanent magnet motors,but also offers high energy efficiency over a wide speed range,which makes the motor an interesting candidate for electric vehicles.
