柴油机两级VNT混联系统整机效率优化

为提高柴油机的余热回收利用率,提出一种基于可变喷嘴环式涡轮VNT（variable nozzle turbine）技术的两级涡轮混联系统。该系统根据柴油机运行工况,通过控制阀门的开闭来实现混联系统中串联工作模式和并联工作模式的转换。以涡轮的有效直径为参数来表征涡轮的流通能力,利用GT-Power仿真平台研究了两种工作模式下增压涡轮和动力涡轮的流通能力对发动机功率、动力涡轮功率及涡轮增压器性能的影响规律；提出了增压涡轮、动力涡轮与发动机的匹配策略；以系统整机效率最优为目标,针对柴油机不同运行工况进行混联方式的优化控制。结果表明:针对柴油机的不同运行工况,通过两级VNT复合系统混联优化运行方案,能够有效回收柴油机废气能量,额定工况下系统整机效率提高5.1%。 

Whole engine efficiency optimization of two stage VNT series parallel system for diesel engines

As the high speed non-salient pole synchronous generator electromagnetic vibration was prominent, the air gap magnetic field and the radial electromagnetic force wave of the synchronous generator were analyzed and calculated by the finite element method.The influence of different magnetic permeability slot wedges and different number of slots on the electromagnetic vibration force of the motor was studied and summarized, and the optimization scheme of reducing the electromagnetic vibration was formed.The correctness of the analysis and calculation of the radial electromagnetic force wave was verified by the comparison of the vibration frequency of the motor foot and the electromagnetic vibration force wave spectrum.On the basis of this, the electromagnetic vibration under the optimization scheme was estimated, the rotor tooth harmonic acceleration was reduced by 13.5 dB and the total vibration level was reduced by 4.6 dB, and the validity of the optimization scheme is verified. The relevant analytical method and optimization measure provided a reliable reference for suppressing the electromagnetic vibration of the high speed generators.