Visual study on the characteristics of liquid and droplet in a novel rotor-stator reactor

Rotor–stator reactor(RSR), an efficient mass transfer enhancer, has been applied in many fields. However,the hydrodynamic characteristics of liquid flow in RSR are still a mystery despite they are fundamental for the mass transfer performance and processing capacity. In view of the above, this paper studies the liquid–liquid flow and liquid holdup in RSR under various conditions with a high-speed camera. The paper firstly demonstrates two flow patterns and liquid holdup patterns that we obtained from our experiment and then presents in succession a flow pattern and a liquid holdup criterion for the transition of film flow to filament flow and complete filling to incomplete filling. It is found that experimental parameters, including rotor–stator distance, rotational speed and volume flow rate exert great influence on the average droplet diameter and size distribution. Besides, by comparison and contrast, we also find that the experimental values match well with our previous predicted calculations of the average diameter, and the relation between the average diameter and the mean energy dissipation rate.

Parameter Modeling and Kinematical Simulation for Rotor and Stator of Screw Pump

The research object used in the dissertation was screw pump, which was widely applied in engineering field. The analysis of end face profile formation was completed on its main working components, i.e., rotor and stator. With the purpose of finding optimal parameters to improve the efficiency of screw pump design, the key technologies involved in the parametric modeling of rotor and stator were analyzed. The three-dimensional (3D) design software SolidWorks was used for the secondary development and parametric modeling of rotor and stator. After that the simulation models of different kinds of screw pumps were established based on the cycloid type, variation coefficient, and screw head number. Finally the COSMOSMotion was used to analyze the motion characteristics on the equidistant line of rotor, including velocity and acceleration. This design and modeling method has been used in screw pump enterprises for design and development, laying the foundation for finite element analysis and further optimization of screw pump.

MATCH-MODE METHOD AND ITS NUMERICAL SIMULATION FOR ROTOR-STATOR INTERACTION SOURCE MODES AND PROPAGATION MODES IN AN ANNULAR DUCT WITH MULTI-TREATMENTS

The suppressing design of the engine nacelle in an aircraft can benefit from the development of the prediction system for the sound fields in engine ducts which includes the prediction of the source generation and that of sound propagation in ducts. First, the acoustic match mode principle between the source modes of rotor stator interaction noise and the propagation modes is presented in this paper. Second, by utilizing this principle, the theoretical prediction method for rotor stator interaction noise generation and its propagation and attenuation in an annular duct with multi treatments is developed. That means that the prediction of sound propagation and attenuation in the segmented ducts might no longer completely depend on the in duct mode measurements, and the investigation on the sound propagation and attenuation in ducts can be accomplished not only by acoustic mode measurement, but also by making use of the source prediction to determine the source modes excited by rotor stator interaction. The effects of fan speed, blade/vane numbers, axial spacing between rotor and stator on the in duct sound attenuation and generated sound power level before and after ducts (also including the sound power level of blade passing frequency and its harmonics at the inlet of ducts) have been numerically calculated by using this prediction method. The reliability of this prediction method is verified by reasonable agreement between the predicted results with measured results in references. By analyzing the results of calculating cases, some reference criteria are provided for the engineering design of the suppressing engine nacelle.

GENERATOR VIBRATION FAULT DIAGNOSIS METHOD BASED ON ROTOR VIBRATION AND STATOR WINDING PARALLEL BRANCHES CIRCULATING CURRENT CHARACTERISTICS

Rotor vibration characteristics are first analyzed, which are that the rotor vibration of fundamental frequency will increase due to rotor winding inter-turn short circuit fault, air-gap dynamic eccentricity fault, or imbalance fault, and the vibration of the second frequency will increase when the air-gap static eccentricity fault occurs. Next, the characteristics of the stator winding parallel branches circulating current are analyzed, which are that the second harmonics circulating current will increase when the rotor winding inter-turn short circuit fault occurs, and the fundamental circulating current will increase when the air-gap eccentricity fault occurs, neither being strongly affected by the imbalance fault. Considering the differences of the rotor vibration and circulating current characteristics caused by different rotor faults, a method of generator vibration fault diagnosis, based on rotor vibration and circulating current characteristics, is developed. Finally, the rotor vibration and circulating current of a type SDF-9 generator is measured in the laboratory to verify the theoretical analysis presented above.

Singularity analysis of Jeffcott rotor-magnetic bearing with time delays

A Jeffcott rotor-magnetic bearing with time delays is investigated in this paper. Firstly, it is found that the characteristic equation of the system satisfies the conditions of the singularity. Secondly, the center manifold reduction and normal form are employed to study the bifurcation from simple zero and zero-purely imaginary singularities. The results of this paper will help to understand the influence of the time delays in feedback loop on the dynamics of rotor-magnetic bearing system.

For Propulsion Applications It Is Possible to Utilize Both the Torque Output of the Rotor and the Reactional Torque Acting on the Stator of the Driving Electric Motor by Linearizing the Stator

This paper presents a novel idea of utilizing the reactional torque of the conventional electric motor as a linear output for propulsion in addition to the conventional torque output of the rotor. The idea is demonstrated by a theoretical proposal of linearizing the stator of one of the most used motors in Electrical Vehicles and Hybrid Vehicles. The proposed Linear Stator Motor is a simple modification without involving any functional change of the conventional motor. Though theoretical, the indicated possible input energy saving of more than 75% as compared to the conventional motor is no surprise, as by linearizing the stator, an almost equal linear propulsion output is added to the conventional rotor output. In addition to this remarkable saving in input energy, the proposed Linear Stator Motor that suits all types of vehicles, can maintain propulsion without the need for a mechanical transmission system. Also, in the case of watercraft and aircraft vehicles, no external mechanical propulsion drive system is required. It is just an internal force that can push the vehicle forward, backward, or laterally, while the conventional rotor output can be utilized for energy recovery by driving a DC generator.

INFLUENCES ON COUPLED LATERAL AND TORSION VIBRATION BEHAVIOR OF RUB-IMPACT ROTOR BY ROTOR-TO-STATOR CLEARANCE

With the establishment of the nonlinear coupled lateral and torsion vibrationequations of rub-impact Jeffcott rotor and through numerical simulations, the influences on lateraland torsion vibration behavior by rotor-to-stator clearance are analyzed, which prove that there isstrong impact on coupled lateral and torsion vibration behavior. Smaller the clearance is, morecomplex the motion of rotor is. When the clearance is larger, the frequency spectrum of rub-impactrotor is mainly composed of 1/2X, 1/3X and 1/4X components. With the decrease of clearance,quasi-periodic and chaotic motions will be present. Under different clearances, the bifurcationdiagrams of lateral and torsion vibrations can be divided into rub-free zone, rub-light zone andthree complex motion zones in which the motion trend of lateral vibration is similar to that of thetorsion vibration. Compared with the lateral vibration, the torsion vibration is of more motionforms and more abundant frequency components in amplitude spectrum.

Adaptive Control of Active Balancing System for a Fast Speed-varying Jeffcott Rotor with Actuator Time Delay

Due to actuator time delay existing in an adaptive control of the active balancing system for a fast speed-varying Jeffcott rotor, if an unsynchronized control force (correction imbalance) is applied to the system, it may lead to degradation in control efficiency and instability of the control system. In order to avoid these shortcomings, a simple adaptive controller was designed for a strictly positive real rotor system with actuator time delay, then a Lyapunov-Krasovskii functional was constructed after an appropriate transform of this sys-tem model, the stability conditions of this adaptive control system with actuator time delay were derived. After adding a filter function, the active balancing system for the fast speed-varying Jeffcott rotor with actuator time delay can easily be converted to a strictly positive real system, and thus it can use the above adaptive controller satisfying the stability conditions. Finally, numerical simulations show that the adaptive controller proposed works very well to perform the active balancing for the fast speed-varying Jeffcott rotor with actuator time delay.

Creation and Development of Turbo-generators with Water-Cooled Stator and Rotor Windings in Shanghai Electrical Machinery Mfg Works

1. An Overview of Manufacture and Operation A turbine generator utilizing a new technology of electrical machinery industry, i.e. the windings of its stator and rotor all being inner water-cooled, was first successfully created in China and was known afterwards as a turbine generator with watercooled stator and rotor windings (Abbrev, TGWSR). The teachers from Zhejiang University came to Shanghai between

无刷双馈电机研究综述与展望

无刷双馈电机具有结构可靠、变频器容量小等优势,非常适合灵活运行于防爆、易燃等特殊或极端工况,近年来受到广泛关注。该文根据无刷双馈电机的基本工作原理,明确了该类电机的命名原则与规范名称;总结了现有定转子方案的结构及性能特点,综合考虑性能指标与结构工艺,提出了转子双套绕组的发展方向;梳理了无刷双馈电机的稳态等效电路模型及基于各类数学模型的优化设计方法,针对现存难以完整考虑不同转速工况性能的不足,阐明了利用新型同步-异步相串联等效电路进行优化设计的思路;对比分析了经典及新近出现的无刷双馈电机控制系统拓扑和控制策略特点,面向典型电动、发电工况建立了完整的电机及控制系统。最后,对无刷双馈电机的上述理论研究问题及工业应用的发展方向进行了总结阐述,为该类电机的深入研究及加快推广应用提供参考和指导。

滚动轴承-JEFFCOTT转子系统非线性动力响应分析

分析了滚动轴承运动时的非线性轴承力,建立了考虑非线性轴承力的滚动轴承-Jeffcott刚性转子系统的动力学方程,并用数值方法对其求解。利用分岔图和poincar映射图,分析了滚动轴承-Jeffcott转子系统的非线性动力响应行为。结果表明:转子系统具有丰富的周期和非周期(拟周期或混沌)响应形式,转子系统进入混沌的主要途径是倍周期分岔,合理的选择转子系统的结构和工作参数,如转速,游隙和阻尼,可降低系统的不稳定性。

含横向裂纹Jeffcott转子刚度及动力学特性研究

以刚性支承的水平Jeffcott裂纹转子为研究对象,建立了不依赖于重力占优假设的动力学方程,在考虑裂纹张开区域对中性轴位置影响的基础上,利用中性轴理论研究裂纹的开闭规律,由截面惯性矩与惯性积得到开闭裂纹截面各方向刚度系数,详细讨论不同裂纹深度和不同转速下系统的动力学行为。结果表明:裂纹的存在对截面的法向与切向刚度系数的影响较大,而耦合刚度系数则始终接近于零值;随着裂纹深度的增加,裂纹的开闭过渡过程越明显,系统响应的频谱图趋向复杂,高阶谐波分量更加明显;当转速等于一阶临界转速的分数倍时,系统的固有频率被激发,系统响应出现分数次共振现象。

吸振器与球平衡器并用控制转子不平衡振动的理论研究

球式自动平衡器(Automatic Ball Balancer,简称ABB)可以在临界转速以上区域完全消除转子未知不平衡量,但其缺点是在临界转速附近会引起大振幅的共振响应和不稳定振荡。为此增加动力吸振器(Dynamic Vibration Absorber,简称DVA)来克服其缺点,改善其抑振性能。以Jeffcott偏心转子模型为研究对象,根据拉格朗日方程建立了吸振器、球平衡器单独使用以及两者结合使用时控制转子不平衡振动的动力学方程,使用谐波平衡法理论求解新耦合系统的振幅表达式,并分析各参数对稳态幅频曲线的影响规律以获得较合适的参数,采用龙格-库塔数值方法计算得到稳态幅频特性图和瞬态振幅时域变化曲线。对比结果表明,两种手段并用的新方案有效降低了转子经过临界共振区时的振动水平,并使转子在临界转速以上区域衰减为零振幅,达到了融合两者优点的目的,具有更优良的抑振效果。

Jeffcott裂纹转子弯扭耦合振动特性分析

以重力决定的开闭裂纹模型为研究对象 ,导出了固定坐标系下该模型的刚度矩阵 ,建立了裂纹转子弯扭耦合振动微分方程 ,并对转子裂纹的升速瞬态响应和影响因素进行了计算机仿真研究。结果表明 :升速过程中 ,弯振存在 1/ 3阶和 1/ 2阶亚谐共振现象 ,扭振出现 1/ 2阶亚谐共振 ;在弯扭左耦合区 ,出现弯扭耦合共振 ;在亚临界转速区 ,存在 1X,2 X和 3X等倍频分量的弯振和扭振 ;影响弯扭耦合振动特性的因素很多 ,包括裂纹刚度、裂纹夹角、质量偏心和阻尼等。

汽轮发电机转子匝间短路对定子热响应特性的影响

本文分析了汽轮发电机转子匝间短路故障前后定子热响应特性,不仅考虑转子匝间短路引起电压下降对发电机强励动作的影响,还研究了热分布不平衡而引起的定子力学响应。首先推导了正常情况和转子匝间短路故障后加强励磁电流下的气隙磁通密度,得到了铁心损耗和绕组铜耗的解析表达式;然后建立了发电机故障前后的三维有限元仿真模型,对不同短路程度故障下的铁心损耗、绕组铜耗与定子温度进行了求解计算;最后实测了CS-5型故障模拟发电机在正常运行和不同短路程度故障下的定子温度,实验结果与理论分析、有限元仿真结果基本一致。结果表明,转子匝间短路故障后由于励磁电流的增强,发电机铁心损耗和绕组铜耗均会增加,定子温度明显上升,并且随着短路程度的增加而加剧;定子端面边缘位置的变形和应力幅值最大并且为热响应下的危险位置。

滑动轴承支承Jeffcott转子的油膜稳定性研究

通过对无限长圆轴承支承的立式Ｊｅｆｆｃｏｔｔ转子系统的油膜稳定性研究，发现其油膜失稳区有上限，在其之上存在一个稳定工作区（上稳定区），由此，提出一种新方法来解决油膜稳定性问题，即让转子在失稳区上方的上稳定区工作。还推荐了一些提高稳定性的措施。

考虑表面粗糙度影响的低温涡轮泵特性与动静间隙流动分析

为分析低温涡轮泵过流部件表面粗糙度对其性能特性的影响,阐明表面粗糙度对涡轮泵动静间隙流场的影响机制,选择增材制造闭式叶轮涡轮氧泵为研究对象,在考虑低温介质热力学效应影响的前提下,采用液氮作为增压输送介质,对涡轮泵低温性能开展实验测试和数值计算。研究结果表明:在13 500~26 000 r/min转速范围内,相较于光滑壁面,考虑过流部件表面粗糙度后,采用液氮作为模拟介质得到的涡轮氧泵数值计算结果与实验测试数据吻合较好;随着离心叶轮及蜗壳等主流表面粗糙度从光滑壁面增加至36μm,涡轮氧泵扬程及效率分别下降了9.1%、10.6%;随着动静间隙过流部件表面粗糙度从0增加至20μm,涡轮泵叶轮轴向力合力系数显著降低了25.8%。研究结果对后续深入揭示表面粗糙度对低温涡轮泵动静间隙流场特性影响规律以及过流部件表面质量分区控制具有重要借鉴意义及参考价值。

主动磁轴承控制器对Jeffcott转子裂纹故障特征的影响

建立主动磁轴承(active magnetic bearing,AMB)系统中裂纹转子的动力学模型,从理论上分析主动磁轴承转子系统中裂纹转子的动力学特性,讨论主动磁轴承的控制方法及控制参数对转子裂纹故障动力特性的影响,以及裂纹对主动磁轴承转子系统的稳定性影响等问题。结果表明,主动磁轴承转子系统中转子的裂纹故障动力特性比传统的裂纹转子的动力特性更为复杂。控制器采用PID控制方式时,传统的用来诊断转子裂纹故障的特征参数在一定条件下能被继续用来检测裂纹的存在;同时,研究结果证明,控制器采用最优控制时,不能采用传统方法检测裂纹。

Jeffcott刚性支承转子系统的稳定性与动刚度分析

高速旋转产生的转轴离心随动载荷效应将对转子系统的稳定性和动刚度产生显著影响。基于同步转动坐标系描述转子系统的相对运动,采用Rayleigh-Ritz方法建立了系统量纲归一化动力学模型,系统分析了Jeffcott转子系统正进动平衡解的稳定性,并研究了刚性支承单圆盘偏心转子系统正进动平衡解的稳定性与动刚度,包括偏心及不同激励频率对系统稳定性和动刚度的影响规律。获得了临界转速与系统参数的关系以及转子动刚度/共振频率随运转速度的变化关系。分析表明:刚性支承单圆盘偏心转子系统的刚度将随着系统运行转速变化,且在超临界运行时具有更高的动刚度和抗扰动能力,进一步厘清了对Jeffcott转子系统动力学行为的一些认识。

燃气轮机透平转静盘腔内流动与传热研究进展

转静系盘腔是燃气轮机二次空气系统中的重要组成部分,盘腔内流动和传热特性对整机安全稳定运行十分重要。随着燃气透平进口温度的不断提升,对透平冷却设计的要求不断提高,透平盘腔流动换热特性研究也越来越受关注。研究人员从流动与换热两个方面对转静系盘腔进行实验测量和数值模拟研究,形成相对比较成熟的研究体系。总结近年来燃气透平转静盘腔流动传热及冷却的相关研究进展,根据结构的不同分别对中心进气和预旋进气转静系盘腔及转静系盘腔的轮缘密封进行介绍,分析3种不同盘腔结构内部流动型态,介绍了预旋系统结构和轮缘密封结构对盘腔内流动传热特性影响的相关实验与数值研究现状。最后,基于当前研究热点和发展趋势,总结并展望了转静系盘腔未来研究的发展方向。