【摘 要】
：
The coaxial cooling fan of the traction motor is the necessary component for the safe operation of high-speed train.Due to the alternately moving direction of the train,the traction motor is designed
【机 构】
：
School of Mechanical Engineering Shanghai Jiao Tong University Shanghai,China,200240
论文部分内容阅读
The coaxial cooling fan of the traction motor is the necessary component for the safe operation of high-speed train.Due to the alternately moving direction of the train,the traction motor is designed at both positive rotation and reverse rotation.With the requirement of similar performance of the centrifugal cooling fan,symmetrical case and straight blade structure is designed for the product.Therefore,the aerodynamic characteristics of the cooling fan are relatively not good,which results in relatively high aerodynamic noise as compared to the conventional fans.In order to study the aerodynamic characteristics and aerodynamic noise,the model of a special motor fan was established.3D numerical simulation of the model was carried out at different rotating speeds.The acoustic analogy method is used to analyze the noise of the centrifugal cooling fan,and the validity of the method is verified.In addition,the operating noise of the cooling fan in the traction motor was tested in the semi-anechoic room.The results show that: corresponding to the different rotating speeds,the flow characteristics at the motor outlet is similar; with the increment of the rotating speed,total sound pressure level is increasing linearly.The simulation results provide the velocity distribution in the fan and find the maximum noise sources strength.From the testing results,the noise problem can be understood better and the structure of the centrifugal cooling fan can be improved to reduce the aerodynamic noise,especially at high rotating speed conditions.
其他文献
基于商业流动分析软件NUMECA,采用Apalart-Allmaras湍流模型以及多重网格方法,对某管线压缩机内部的三维粘性流动进行模拟.根据模拟结果,对叶轮、无叶扩压器、弯道、回流器等部件的结构进行优化,从而实现了这些部件流动涡的控制,大大降低了这些部件的流动损失,最终完成了某管线压缩机基本级的气动开发.对该管线压缩机模型级进行了性能实验,实验结果表明:在设计马赫数下,该管线压缩机模型级性能曲线
英语新课标实施以来,要求充分发挥学生主观能动性,提高学生学习英语知识的兴趣,激发学生自主学习的积极性。为此,我们教师要坚持以人为本的教学理念,打造轻松、愉快、民主、和谐的英语课堂,增强学生学习的自信心,享受英语学习带来的乐趣,激发学生主体意识,让学生成为课堂真正的主人,从而自发地参与到课堂学习中来,通过理论知识学习和实践活动参与提高学生英语综合素养,实现英语教学的目标。
甲状腺淋巴瘤（TL）在临床较为少见,好发于60～70岁的女性[1]。不同病理类型的TL治疗手段不同,预后也不同,因而治疗前的诊断具有重要意义。TL的病理类型主要为弥漫大B细胞淋巴瘤（DLBCL）和黏膜相关淋巴组织淋巴瘤（MALT）[2],研究表明,不同病理类型的TL有不一样的超声表现[3],
本文采用离心通风机现代气动设计方法,选用效率高、噪声低的后弯叶轮,根据核级风机运行参数,初步设计并对风机内部流场进行三维数值模拟.通过分析风机全压、效率及内部流场,分别对风机叶片数目、叶片进口角、进口加速系数等参数进行优化,优化后风机效率达到87.74％,全压5328.6Pa,符合设计要求.样机的性能测试结果表明,在设计工况下,离心风机的效率可达87％以上,数值模拟与试验结果符合,所设计的离心通风
随着国内天然气储运业务的快速发展,天然气管道压缩机组的可靠性及异常工况响应能力越来越重要,集成式式压缩机能够解决目前高速直连电驱机组调速范围窄、故障频繁、油气持续排放污染环境等诸多问题.结合国外集成式压缩机应用现状,首次梳理了从各类集成式压缩机机型结构、功率等关键参数,对比了国外集成式压缩机的优势与特点,提出了集成式压缩机研制的关键技术问题与难点.借鉴国外集成式压缩机设计理念,提出天然气长输管道集
Flutter analysis is an important part of the design process of modern steam turbines.The fidelity of flutter analysis for steam turbines has increased rapidly over the last 15 years,mainly due to the
对于超高水头(水头大于700m)水泵水轮机，机组的安全性和稳定性是最高要求。如机组的动静干涉问题、水泵驼峰问题、水泵空化问题、水轮机S 形曲线和机组过渡过程的安全性问题。如果机组动静干涉很强，直接影响机组的稳定运行品质，动静干涉越强，机组的振动越严重，也会造成较大的能量损失。水泵驼峰决定着机组在高扬程打水的能力，驼峰越明显，向高扬程打水的能力越弱。空化安全余量直接决定着机组运行寿命，机组的空化安全
透平机械的主轴的不同位置承受着不同的应力，其中包括传递功率的扭转力矩、叶轮叶片运转时的振动应力，转子本身旋转时的循环应力以及高低压两端温差引起的热应力等.在苛刻服役环境和变工况环境下，主轴面临磨损、腐蚀和疲劳等问题.这些问题严重影响转子、甚至机组的安全可靠性.API 617 第8 版标准对压缩机轴的处理提出了原则性的要求.本文作者与国内和国际透平机械厂家合作，对API 687 和API 617 进
电影《春桃》和《玛丽娅·布劳恩的婚姻》是20世纪下半叶,中国和欧洲两部以女性伦理为主题的经典之作。两部影片均在叙事上运用相类似的构思,展现了处于相似社会背景之下的两位东西方女性如何在社会秩序重建的"废墟"之上,完成对自我身份的颠覆与重建。文章借其深刻剖析了女性与时代命运、女性与男权社会、女性对自我身份的认定与思考等社会问题。
With the high reliability and high availability they provide,active magnetic bearings(AMBs)have found increasing application in high-speed and high-performance turbomachinery.The oil & gas and energy