Effect of Temperature Distribution on Critical Speeds of a Dual-Rotor System

2014 ◽  
Vol 709 ◽  
pp. 21-24
Author(s):  
Gui Yu Xin ◽  
Ke Ming Wang ◽  
Mei Jiao Qu ◽  
Tian Yin Wang
Keyword(s):  
High Pressure ◽  
Temperature Distribution ◽  
Critical Speed ◽  
Axial Direction ◽  
Calculation Model ◽  
Rotor System ◽  
Effect Of Temperature ◽  
Critical Speeds ◽  
Calculation Results ◽  
The Impact

A dual-rotor calculation model which can expand freely in the axial direction is established in this paper, and the effects of one-dimensional axial temperature distribution on critical speeds of the dual-rotor system are analyzed with finite element method. The temperature distribution of the dual-rotor system is given referring to that of similar aero-engine rotor system. Assuming that the left end temperature remains at 0 °C, and the highest temperature on the section of the high-pressure turbine disk is 0 °C, 200 °C, 400 °C, 600 °C, and 800 °C respectively, the critical speeds of the dual-rotor system are calculated, analyzed and compared. Calculation results show that, with the increase of the highest temperature of the dual-rotor system, the reduction percentage of the critical speeds increases, and the impact on the first critical speed is most obvious. When the highest temperature is 800 °C, the first critical speed of the rotor system excited by the low-pressure rotor reduces 13.13%, and that excited by the high-pressure rotor reduces 13.49%.

scholarly journals Dynamical analysis of hollow-shaft dual-rotor system with circular cracks

2020 ◽  
pp. 146134842094828
Author(s):  
Yang Yongfeng ◽  
Wang Jianjun ◽  
Wang Yanlin ◽  
Fu Chao ◽  
Zheng Qingyang ◽  
...  
Keyword(s):  
Critical Speed ◽  
Equations Of Motion ◽  
Harmonic Balance Method ◽  
Circular Crack ◽  
Rotor System ◽  
Resonance Phenomenon ◽  
Dynamical Analysis ◽  
Dynamical Response ◽  
Critical Speeds ◽  
Hollow Shaft

In this paper, we considered a dual-rotor system with crack in shaft. The influence of circular crack in hollow shaft on dynamical response was studied. The equations of motion of 12 elements dual-rotor system model were derived. Harmonic balance method was employed to solve the equations. The critical speed and sub-critical speed responses were investigated. It was found that the circular crack in hollow shaft had greater influence on the first-backward critical speed than the first-forward critical speed. Owing to the influence of crack, the vibration peaks occurred at the 1/2, 1/3 and 1/4 critical speeds of the rotor system, along with a reduction in sub-critical speeds and critical speeds. The deeper crack away from the bearing affected the rotor more significantly. The whirling orbits, the time-domain responses and the spectra were obtained to show the super-harmonic resonance phenomenon in hollow-shaft cracked rotor system.

The Dynamic Simulation and Strength Analysis of the Integrated General Suspension Rack Connector for an Ejection System

2013 ◽  
Vol 712-715 ◽  
pp. 1545-1549
Author(s):  
Jian Bin Zhen ◽  
Cheng Xu ◽  
Tao Wang
Keyword(s):  
High Pressure ◽  
High Frequency ◽  
Dynamic Theory ◽  
Calculation Model ◽  
Strength Analysis ◽  
Original Design ◽  
Locking Mechanism ◽  
Design Plan ◽  
Improved Design ◽  
The Impact

Because the impact of the connector is very important, the mathematics calculation model for the key components of the integrated general suspension rack for an airborne ejection was established, which were under the two questions of safety hanging and accuracy ejection. The integrated general suspension rack was operated by high pressure gas which was generated by the burning of the ejector cartridge, and the entire movement process of the integrated general suspension rack pushing the piston to unlock the locking mechanism and completely discarding from the airborne was analyze using the dynamic theory of gases. The modified and the original design plan for the integrated general connector were analyzed by the strength analysis. Through analysis, compared with original design, the improved design can well achieve the desired goal. The improved design of the connector is checked by field inspection of high frequency vibration to make sure the integrated general suspension rack can be hanged stably on the airborne and being flung out accurately by the modified design plan.

scholarly journals Analysis of the Partial Demagnetization Process of Magnets in a Line Start Permanent Magnet Synchronous Motor

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5562
Author(s):  
Mariusz Baranski ◽  
Wojciech Szelag ◽  
Wieslaw Lyskawinski
Keyword(s):  
Permanent Magnet ◽  
Permanent Magnet Synchronous Motor ◽  
Experimental Studies ◽  
Experimental Tests ◽  
Synchronous Motor ◽  
Effect Of Temperature ◽  
Start Up ◽  
Calculation Results ◽  
Thermal Phenomena ◽  
The Impact

The paper justifies the validity of analyzing the impact of temperature and the process of partial demagnetization of magnets on the operating parameters of machines. To analyze this impact, a field model of coupled electromagnetic and thermal phenomena in a permanent magnet synchronous motor was proposed. The non-linearity of the magnetic circuit, the effect of temperature on the magnetic, electrical and thermal properties of the materials as well as the developed method of modeling the process of partial demagnetization of the magnet were taken into account. Based on this model, an algorithm and software were developed to analyze the effect of temperature and the process of partial demagnetization of magnets on the work of the line start permanent magnet synchronous motor (LSPMSM). The elaborated software was used to study the effect of temperature during the motor starting phase on the magnetization state of the magnets after the start-up process. The calculation results were compared to the results of experimental studies. The experimental tests were carried out on a specially constructed test stand. The results of the research on the process of partial demagnetization of the magnets are presented and the conclusions resulting therefrom formulated.

Research on Improvement of Merchant Shear Angle Model

2014 ◽  
Vol 894 ◽  
pp. 192-200 ◽  
Author(s):  
Shu Ting Wang ◽  
Yu Cheng Zhang ◽  
Wei Dong Gou ◽  
Chuan Jiang Liu
Keyword(s):  
Metal Cutting ◽  
Friction Angle ◽  
Calculation Model ◽  
Shear Angle ◽  
Zone Model ◽  
Analysis Model ◽  
Calculation Results ◽  
The Impact ◽  
Angle Calculation ◽  
Key Parameter

Shear angle is a key parameter to characterize the metal cutting. In this paper the Merchant analysis model of shear angle is improved. The impact of shear angle on the shear stress is quantitatively analyzed by using of the unequal division shear zone model and Johnson-Cook constitutive model, and the functional relationship between the tool-chip friction angle and the shear angle is established by Schulz empirical formula. Thus the new shear angle calculation model is established. Calculation results and experiments verify the effectiveness of the improved Merchant model.

Analysis to Dynamic Characteristics Influence on Bearing-Load Sensor to the Rotor System

2011 ◽  
Vol 308-310 ◽  
pp. 2551-2554
Author(s):  
Xin Yu Pang ◽  
Zhao Jian Yang
Keyword(s):  
Finite Element ◽  
Dynamic Equation ◽  
Critical Speed ◽  
Rotor System ◽  
The Other ◽  
Test Bed ◽  
Finite Element Software ◽  
Load Sensor ◽  
Bearing Load ◽  
The Impact

For a multi-bearing rotor test bed, using the load sensor designed specially measured directly the bearing load value. In order to analyze the dynamic influence of the load sensor on the rotor system, the dynamic equation of the rotor system with the load sensor established to do the qualitative analysis. On the other hand, quantitative analyzing the two structures that the sensor is installed and is not by finite element software ANSYS, and obtained the impact value. The results show that the load sensor reduced the critical speed of the rotor system, but the effect is not, can be appropriately adjusted work speed according to the results of the analysis.

The Dynamic Analysis of SFD-Sliding Bearing Flexible Rotor System Based on Optimization Design

2012 ◽  
Vol 159 ◽  
pp. 355-360
Author(s):  
Ji Yan Wang ◽  
Rong Chun Guo ◽  
Xu Fei Si
Keyword(s):  
High Speed ◽  
Optimization Design ◽  
Critical Speed ◽  
Structural Parameters ◽  
Rotor System ◽  
Flexible Rotor ◽  
Optimization Analysis ◽  
Sliding Bearing ◽  
Critical Speeds ◽  
Design Variables

The paper establishes the mechanical model of SFD-sliding bearing flexible rotor system, adopting Runge-Kutta method to solve nonlinear differential equation, thus acquiring the unbalanced response curve and then gaining the first two critical speeds of the system. Meanwhile, the paper analyzes the sensitivity of the system on the first two critical speeds towards structural parameters, offering design variables to optimization analysis. Based on sensitivity analysis, genetic algorithm is employed to give an optimization analysis on critical speed, which aims to remove critical speed from working speed as much as possible. The critical speed ameliorates after the optimization which supplies theoretical basis as well as theoretical analysis towards the dynamic stability of high-speed rotor system and provides reference for the design of such rotor system.

scholarly journals A Helical Charge Simulation based 3-D Method for Calculating AC Stranded Conductor’s Corona Loss in the Corona cage

2017 ◽  
Author(s):  
Yunpeng Liu ◽  
Shilong Huang ◽  
Shugang Liu ◽  
Daran Liu ◽  
Zhicheng Huang
Keyword(s):  
Transmission Lines ◽  
Axial Direction ◽  
Simulation Method ◽  
Calculation Model ◽  
Loss Calculation ◽  
Simulation Based ◽  
Measurement Results ◽  
Calculation Results ◽  
Ac Transmission ◽  
Design Factors

Corona loss generated from conductors is one of the important design factors on ac transmission lines. Based on helical charge simulation method, the 3-D corona loss calculation model considering the conductors’ outer strands in the corona cage is established. With regard to 2-D corona-loss calculation method, the calculation model proposed in this paper can take the electric field strength’s nonuniformity along the axial direction of stranded conductor into consideration, furthermore, it can also calculate the corona loss when the conductor has sag. The calculation results of the LGJ-300/40 and LGJ-400/35 in the small corona cage well coincide with the measurement results, which indicates that the corona-loss calculation model is appropriate. In addition, the corona loss of the bundle conductors 4 × LGJ720 with sag in UHV corona cage is also analyzed.

scholarly journals Modeling Cantilever Branch Structure of Aero-Engine Power Turbine and Analyzing Its Influence

2018 ◽  
Vol 36 (4) ◽  
pp. 728-734 ◽  
Author(s):  
Yebao Xia ◽  
Xingmin Ren ◽  
Yongfeng Yang
Keyword(s):  
Critical Speed ◽  
Vibration Mode ◽  
Structural Parameters ◽  
Rotor System ◽  
Unbalance Response ◽  
Power Turbine ◽  
Aero Engine ◽  
Turbine Component ◽  
Calculation Results ◽  
Turbine Disks

In the power turbine component of an aero-engine, there exists a unique cantilever branch structure, on which turbine disks are mounted. Due to the cantilever's characteristics, this structure exhibits a vibration of large amplitude; thus its characteristics need to be studied in detail.In this paper, the motion equations combining the structure and the shaft were deduced; then its vibration mode was given, and the criticl speed was computed; finally the unbalance response of an integrated rotor system was simulated.The calculation results are compared with the simulation results without considering the branch structure.Some key parameters' influences are studied thoroughly, e.g., the branch shaft's length, the flange's offset and the installation orientation. As the results show, the branch structure has a large influence on the vibration mode and critical speed of the rotor system, thus it should not be simplified and ignored in modelling; After adjusting the branch structure's parameters, the characteristics of a vibration mode do not change, and the effects of branch structural parameters on critical speed are closely related to the corresponding vibration mode; the bending stiffness and the critical speed of the rotor system both decreased with increasing branch shaft's length; if reducing the flange's offset and fabricating the branch structure reversely, a sharp increase in the unbalance response of the turbine disc will occur. In conclusion, the dynamical characteristics of the integrated rotor system can be optimized through reasonably designing the branch structure.

Effect of temperature on the strength of a centrifugal compressor impeller for a turbocharger

2012 ◽  
Vol 227 (5) ◽  
pp. 896-904 ◽  
Author(s):  
Xinqian Zheng ◽  
Lei Jin ◽  
Tao Du ◽  
Binlin Gan ◽  
Fenghu Liu ◽  
...  
Keyword(s):  
High Pressure ◽  
Tensile Strength ◽  
Temperature Distribution ◽  
Ultimate Tensile Strength ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Critical Role ◽  
Effect Of Temperature ◽  
High Pressure Ratio ◽  
Compressor Impeller

High pressure ratio turbocharger technology is used to decrease fuel consumption, reduce emissions and improve power density of an internal combustion engine. The centrifugal compressor is the turbocharger’s core component. The reliability of its impeller becomes critical as the pressure ratio gets higher and the temperature starts playing an important role. In order to study the effect of the flow temperature on the reliability of a centrifugal compressor impeller, solid–fluid coupling is used to calculate the temperature distribution on the impeller surface. This temperature distribution is then applied as boundary condition in three-dimensional finite element analysis to analyze impeller stress. The results show that the percentage of impeller stress caused by thermal load remains approximately constant (about 2%) at different pressure ratios, which does not increase with increasing pressure ratio. Centrifugal load plays an absolutely critical role in the impeller stress at different pressure ratios. High pressure ratio also leads to an increase of air temperature, which causes higher material temperature and consequently the lower ultimate tensile strength of the impeller material. The maximum compressor pressure ratio which the impeller can bear decreases from 4.6 to 4.2 for the researched compressor if the effect of temperature on the ultimate tensile strength was considered. That means the effect of the temperature on compressor impeller strength and reliability at high pressure ratio should be considered while it can be ignored at low pressure ratio.

scholarly journals ДОСЛІДЖЕННЯ ВПЛИВУ ЗМІЩЕННЯ ПАКУВАННЯ ВЗДОВЖ ОСІ БОБІНОТРИМАЧА НА КРИТИЧНІ ШВИДКОСТІ

2020 ◽  
Vol 144 (2) ◽  
pp. 13-23
Author(s):  
Б. С. Завертанний ◽  
О. П. Манойленко ◽  
О. О. Акимов
Keyword(s):  
High Speed ◽  
Center Of Mass ◽  
Axial Direction ◽  
Dynamic Loads ◽  
Practical Significance ◽  
Stable Operation ◽  
Direct Drive ◽  
Critical Speeds ◽  
The Impact

Creation of a mathematical model of the mechanism of winding of rewinding machines, research of influence of size of shift of packing on critical speeds and development of recommendations for the decision of the set task. Method. When working out the thread for packaging, high-speed winding mechanisms are subject to high requirements, both for the quality of the resulting packaging and for the speed of the bobbin holder. When installing the spool on the spool holder, it is possible to shift it in the axial direction from the design position, which leads to a change in the position of the center of mass of the package with the spool, and in accordance with changes in dynamic loads on the spool holder. Therefore, there is a need to determine the magnitude of the impact of the displacement of the package along the axis of the bobbin holder on the operating speeds of the equipment and the quality of the resulting packages. In the winding process, the placement of the package on the bobbin holder of the winding mechanism of the rewinding machine plays an important role. The displacement of the center of mass of the package affects both the operating speed of the equipment and the quality of the package. In rewinding machines, a mechanism for controlling the thickness of the package is installed, which controls the speed processes during winding. When the coil is shifted towards the top of the cone, incomplete packing (less weight) is developed. When shifted to the side opposite the top of the packing cone, on the contrary, the weight of the packing increases. In addition, the magnitude of the displacement of the package affects the dynamic loads of the winding mechanism. Results. The influence of the magnitude of the packing displacement along the axis of the bobbin holder on the critical speeds of the winding mechanism and the quality of packing is determined. Scientific novelty. The study and analysis of the influence of the magnitude of the displacement of the bobbin with packaging on the critical speeds of the winding mechanism are conducted. The magnitude of the influence of the position of the masses of the center of the coil with packing relative to the bobbin holder on the value of the critical speeds of the winding mechanism is determined. The obtained results allow to control the range of working speeds of the winding mechanism depending on the parameters of the position of the spool on the spool holder, which can be used to adjust the speed of the winding process when packing the spool and make changes when designing the rewinding equipment. The method of determining the maximum possible speeds in the process of rewinding textile material on rewinding machines with direct drive of the bobbin, taking into account the position of the bobbin on the bobbin holder, which can be used in the design of new mechanisms or modernization of existing ones. Practical significance. A dynamic model of the winding mechanism has been developed. The magnitude of the influence of packing displacement on critical speeds is shown. Methods and designs for improving the quality of packaging and stable operation of equipment are proposed.

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