Journal articles on the topic 'High speed rotor'
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1
Gerlach, Martin Enno, Maximilian Zajonc, and Bernd Ponick. "Mechanical stress and deformation in the rotors of a high-speed PMSM and IM." e & i Elektrotechnik und Informationstechnik 138, no. 2 (March 2, 2021): 96–109. http://dx.doi.org/10.1007/s00502-021-00866-5.
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AbstractHigh-speed electric machines are gaining importance in the field of traction drives and aviation due to their high power density. The evaluation of the mechanical stress in the rotor is one crucial part in the design process for this type of machines. The mechanical stress cannot be measured directly. Accordingly, a validation of the calculated mechanical stress is difficult and normally not performed. Instead of the mechanical stress, the deformation at the rotor surface can be measured using a spin test machine with distance sensors. The deformation can then be used to validate the calculation results.In this paper, the mechanical load exerted on an IM rotor for a $60\,\text{kW}/20000\,\frac{1}{\text{min}}$ 60 kW / 20000 1 min high-speed electric machine and an PMSM rotor for a $75~\text{kW}/25000\,\frac{1}{\text{min}}$ 75 kW / 25000 1 min high-speed electric machine is analysed in detail. The mechanical stress and the deformation are calculated and analysed using a FEM simulation model. Then, a spin test is performed on the two rotors. First, the burst speed is determined by operating two rotor samples above their defined test speed. Then, the deformation is measured at the rotor surface for different operating speeds and the defined test speed. The measurement and the simulation results are compared and discussed.It can be shown that the two designs do not exceed the maximum mechanical stress for the defined operating range. In the deformation measurement of the IM rotor, a plastic deformation up to $\varepsilon _{\text{IM, pl}} = 8$ ε IM, pl = 8 μm and elastic deformation up to $\varepsilon _{\text{IM, el}}=22$ ε IM, el = 22 μm can be seen. In regards to plastics, PMSM rotor expands up to $\varepsilon _{\text{PMSM, pl}}= 5$ ε PMSM, pl = 5 μm. The maximum elastic deformation of the PMSM rotor is $\varepsilon _{\text{PMSM, el}}=40$ ε PMSM, el = 40 μm. The comparison of the calculated and the measured elastic deformation shows good accordance for the two rotor types. Both models are capable of describing the deformation and the state of stress in the rotors. In burst tests, both rotors withstand rotational speeds far above the defined test speed.
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Liu, Yongguang, Xiaohui Gao, Xiaowei Yang, and Yixuan Wang. "Optimization Design of the Ultra-High-Speed Vertical Rotor’s Supporting Mechanism." Mathematical Problems in Engineering 2014 (2014): 1–11. http://dx.doi.org/10.1155/2014/320240.
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How to increase the rotational speed and decrease vibration of the rotor in the acceleration has become an attractive subject, especially for the vertical rotors. This paper introduces a novel supporting mechanism to make the vertical rotor work at 80000 r/min smoothly. How to design and optimize the sensitive parameters of the supporting mechanism is the core problem to reduce the vibration in passing through critical speeds. Therefore, the FEM (finite element method) considering the gyroscopic couple is introduced to get the dynamic characteristic of the rotor system. The matching principle of the upper and lower supporting mechanism in the two-degree freedom system is extended to the multiple degree-freedom system, which is applied to optimize the parameters of the supporting mechanism combining with dynamic characteristic of the rotors system. At last, the rotor system can work at 80000 r/min smoothly in experiment.
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Yuan, Y., D. Thomson, and R. Chen. "Variable rotor speed strategy for coaxial compound helicopters with lift–offset rotors." Aeronautical Journal 124, no. 1271 (September 27, 2019): 96–120. http://dx.doi.org/10.1017/aer.2019.113.
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ABSTRACTThe coaxial compound helicopter with lift-offset rotors has been proposed as a concept for future high-performance rotorcraft. This helicopter usually utilizes a variable-speed rotor system to improve the high-speed performance and the cruise efficiency. A flight dynamics model of this helicopter associated with rotor speed governor/engine model is used in this article to investigate the effect of the rotor speed change and to study the variable rotor speed strategy. Firstly, the power-required results at various rotor rotational speeds are calculated. This comparison indicates that choice of rotor speed can reduce the power consumption, and the rotor speed has to be reduced in high-speed flight due to the compressibility effects at the blade tip region. Furthermore, the rotor speed strategy in trim is obtained by optimizing the power required. It is demonstrated that the variable rotor speed successfully improves the performance across the flight range, but especially in the mid-speed range, where the rotor speed strategy can reduce the overall power consumption by around 15%. To investigate the impact of the rotor speed strategy on the flight dynamics properties, the trim characteristics, the bandwidth and phase delay, and eigenvalues are investigated. It is shown that the reduction of the rotor speed alters the flight dynamics characteristics as it affects the stability, damping, and control power provided by the coaxial rotor. However, the handling qualities requirements are still satisfied with different rotor speed strategies. Finally, a rotor speed strategy associated with the collective pitch is designed for maneuvering flight considering the normal load factor. Inverse simulation is used to investigate this strategy on maneuverability in the Push-up & Pull-over Mission-Task-Element (MTE). It is shown that the helicopter can achieve Level 1 ratings with this rotor speed strategy. In addition, the rotor speed strategy could further reduce the power consumption and pilot workload during the maneuver.
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Han, D., and G. N. Barakos. "Variable-speed tail rotors for helicopters with variable-speed main rotors." Aeronautical Journal 121, no. 1238 (February 23, 2017): 433–48. http://dx.doi.org/10.1017/aer.2017.4.
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ABSTRACTVariable tail rotor speed is investigated as a method for reducing tail rotor power, and improving helicopter performance. A helicopter model able to predict the main rotor and tail rotor powers is presented, and the flight test data of the UH-60A helicopter is used for validation. The predictions of the main and tail rotor powers are generally in good agreement with flight tests, which justifies the use of the present method in analysing main and tail rotors. Reducing the main rotor speed can result in lower main rotor power at certain flight conditions. However, it increases the main rotor torque and the corresponding required tail rotor thrust to trim, which then decreases the yaw control margin of the tail rotor. In hover, the tail rotor may not be able to provide enough thrust to counter the main rotor torque, if it is slowed to follow the main rotor speed. The main rotor speed corresponding to the minimum main rotor power increases, if the change of tail rotor power in hover is considered. As a helicopter translates to cruise, the induced power decreases, and the profile power increases, with the profile power dominating the tail rotor. Reducing the tail rotor speed in cruise reduces the profile power to give a 37% reduction in total tail rotor power and a 1.4% reduction to total helicopter power. In high-speed flight, varying the tail rotor speed is ineffective for power reduction. The power reduction obtained by the variable tail rotor speed is reduced for increased helicopter weight.
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Ehrich, F. F., and S. A. Jacobson. "Development of High-Speed Gas Bearings for High-Power Density Microdevices." Journal of Engineering for Gas Turbines and Power 125, no. 1 (December 27, 2002): 141–48. http://dx.doi.org/10.1115/1.1498273.
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A 4.2-mm diameter silicon rotor has been operated in a controlled and sustained manner at rotational speeds greater than 1.3 million rpm and power levels approaching 5 W. The rotor, supported by hydrostatic journal and thrust gas bearings, is driven by an air turbine. This turbomachinery/bearing test device was fabricated from single-crystal silicon wafers using micro-fabrication etching and bonding techniques. We believe this device is the first micro-machine to operate at a circumferential tip speed of over 300 meters per second, comparable to conventional macroscale turbomachinery, and necessary for achieving high levels of power density in micro-turbomachinery and micro-electrostatic/ electromagnetic devices. To achieve this level of peripheral speed, micro-fabricated rotors require stable, low-friction bearings for support. Due to the small scale of these devices as well as fabrication constraints that limit the bearing aspect ratio, the design regime is well outside that of more conventional devices. This paper focuses on bearing design and test, and rotordynamic issues for high-speed high-power micro-fabricated devices.
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Bin, Guangfu, Liang Zhang, Feng Yang, and Anhua Chen. "The Influence of Ring-Speed Ratio Dynamic Change on Nonlinear Vibration Response of High-Speed Turbocharger Rotor System." Shock and Vibration 2021 (October 28, 2021): 1–9. http://dx.doi.org/10.1155/2021/9649232.
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The ring-speed ratio is a comprehensive dynamic index of floating ring bearing structure and operating parameters, which directly affects the dynamic behavior of the turbocharger rotor system. The cross stiffness of ring-speed ratio and floating ring bearing and the work of oil film force are analyzed. The influence of dynamic ring-speed ratio change on the vibration response of floating ring bearing was studied. The finite element model of the rotor-floating ring bearing system is constructed; its model parameters are verified through the measured critical rotor speed. Newmark integral method is used to analyze the nonlinear transient response. The results show that when the ring-speed ratio is between 0.18 and 0.24, the rotor is in a good operating state; when it increases from 0.24 to 0.36, the rotor vibration is dominated by frequency division, and the system will be less stable. The square of the ring-speed ratio is inversely proportional to the rotational speed of the journal where the subfrequency vibration occurs. It helps to know the nonlinear vibration by judging the journal speed when the rotor vibration occurs in subfrequency. The conclusion provides a reference for the mechanical dynamics design and intelligent management and maintenance of this kind of turbine rotors.
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Sim, Kyuho, and Daejong Kim. "Design of Flexure Pivot Tilting Pads Gas Bearings for High-speed Oil-Free Microturbomachinery." Journal of Tribology 129, no. 1 (July 27, 2006): 112–19. http://dx.doi.org/10.1115/1.2372763.
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This paper introduces flexure pivot tilting pad gas bearings with pad radial compliance for high-speed oil-free microturbomachinery. The pad radial compliance was for accommodation of rotor centrifugal growth at high speeds. Analytical equation for the rotor centrifugal growth based on plane stress model agreed very well with finite element method results. Parametric studies on pivot offset, preload, and tilting stiffness were performed using nonlinear orbit simulations and coast-down simulations. Higher preload and pivot offset increased both critical speeds of the rotor-bearing system and onset speeds of instability due to the increased wedge effect. Pad radial stiffness and nominal bearing clearance were very important design parameters for high-speed applications due to the physically existing rotor centrifugal growth. From the series of parametric studies, the maximum achievable rotor speed was limited by the minimum clearance at the pad pivot calculated from the rotor growth and radial deflection of pads due to hydrodynamic pressure. Pad radial stiffness also affects the rotor instability significantly. Small radial stiffness could accommodate rotor growth more effectively but deteriorated rotor instability. From parametric studies on a bearing with 28.5mm in diameter and 33.2mm in length, optimum pad radial stiffness and bearing clearance are 1-2×107N∕m and 35μm, respectively, and the maximum achievable speed appears 180krpm. The final design with suggested optimum design variables could be also stable under relatively large destabilizing forces.
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Rezgui, Djamel, and Mark H. Lowenberg. "Nonlinear Blade Stability for a Scaled Autogyro Rotor at High Advance Ratios." Journal of the American Helicopter Society 65, no. 1 (January 1, 2020): 1–19. http://dx.doi.org/10.4050/jahs.65.012005.
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Despite current research advances in aircraft dynamics and increased interest in the slowed rotor concept for high-speed compound helicopters, the stability of autogyro rotors remains partially understood, particularly at lightly loaded conditions and high advance ratios. In autorotation, the periodic behavior of a rotor blade is a complex nonlinear phenomenon, further complicated by the fact that the rotor speed is not held constant. The aim of the analysis presented in this article is to investigate the underlying mechanisms that can lead to rotation-flap blade instability at high advance ratios for a teetering autorotating rotor. The stability analysis was conducted via wind tunnel tests of a scaled autogyro model combined with numerical continuation and bifurcation analysis. The investigation assessed the effect of varying the flow speed, blade pitch angle, and rotor shaft tilt relative to the flow on the rotor performance and blade stability. The results revealed that rotor instability in autorotation is associated with the existence of fold bifurcations, which bound the control-input and design parameter space within which the rotor can autorotate. This instability occurs at a lightly loaded condition and at advance ratios close to 1 for the scaled model. Finally, it was also revealed that the rotor inability to autorotate was driven by blade stall.
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Manas, MP, and AM Pradeep. "Stall inception mechanisms in a contra-rotating fan operating at different speed combinations." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 234, no. 8 (December 17, 2019): 1041–52. http://dx.doi.org/10.1177/0957650919893831.
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Contra-rotating fan is a concept that can possibly replace the present-day conventional fans due to its several aerodynamic advantages. It has the potential to improve the stability limit and can achieve a higher pressure ratio per stage. One of the advantages of a contra-rotating fan is its capability to operate both the rotors at different speeds. In the present study, experiments are carried out at different speed combinations of the rotors and the stall inception phenomenon is captured using high-response unsteady pressure sensors placed on the casing upstream of the leading edge of rotor-1. The unsteady pressure data are investigated using wavelet and Fourier analysis techniques. It is observed that the mechanism of stall inception is different for different speed combinations. The pre-stall disturbances fall in different frequency ranges for different speed combinations. For the range of speed combinations investigated, the frequency of appearance of stall cells of rotor-1 does not depend on the speed of rotor-2. A higher speed of rotation of rotor-1 leads to a higher frequency of appearance of stall cells and a lower speed of rotation of rotor-1 leads to a lower frequency of appearance of stall cells. For all the speed combinations, there is a range of frequency where no disturbance is observed and this range is termed as the ‘no-disturbance zone’. Disturbances are observed at lower frequencies and at frequencies close to the blade passing frequency. In order to understand the flow physics in detail, computational analysis is carried out for different speed combinations of the rotors. For a higher speed of rotor-2, it is observed that the suction effect of rotor-2 is significant enough to pull the tip-leakage flow towards the axial direction. Thus, the suction effect of rotor-2 plays a significant role in determining the stall of the stage.
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Ma, Xunxun, Shujia Li, Wangliang Tian, Xiqiang Qu, Shengze Wang, and Yongxing Wang. "Dynamic Behavior Analysis of the Winding Rotor with Structural Coupling and Time-Frequency Varying Parameters: Simulation and Measurement." Applied Sciences 11, no. 17 (September 1, 2021): 8124. http://dx.doi.org/10.3390/app11178124.
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To satisfy the requirements of high speed, large capacity and constant winding, a textile winding rotor needs to work in a wide rotation speed range and frequently pass through critical speed points. Thus, the winding rotor adopts the flexible long shaft coupling structure and flexible support with rubber O-rings. This kind of rotor has a multi-coupling structure and frequency-dependent parameters characteristics, especially representative and universal in the dynamic analysis method of the high-speed rotor. In this paper, an approach was proposed to investigate the dynamic behavior of the winding rotor considering the flexible coupling and frequency-dependent supporting parameters. Firstly, a dynamic model of the winding rotor was established by using a Timoshenko beam element. Its dynamic behaviors were simulated by considering the time-varying rotation speed and the frequency-dependent parameters of flexible support. Secondly, a non-contact measuring device was developed for measuring the vibration displacement of the winding rotor in three different speed-up times. Finally, based on simulation and measurement data, how flexible support parameters and the speed-up time affect the winding rotor passing through the critical speed point of the rotor smoothly is revealed. The methods and findings reported here can be used for theoretical and experimental vibration analysis of other types of high-speed flexible rotors.
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Amer, Kenneth B. "Technical Note: High Speed Rotor Aerodynamics." Journal of the American Helicopter Society 34, no. 1 (January 1, 1989): 63. http://dx.doi.org/10.4050/jahs.34.1.63.
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Ehrich, F. F. "Spontaneous Sidebanding in High Speed Rotordynamics." Journal of Vibration and Acoustics 114, no. 4 (October 1, 1992): 498–505. http://dx.doi.org/10.1115/1.2930291.
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Several observations have been made in the Fourier spectra of high speed rotor-dynamic response of uniformly spaced frequency spikes on either side of key synchronous or subharmonic or superharmonic response frequencies. In instances where this so-called “sidebanding” could not readily be explained as the nonlinear interaction or combination tones of two distinct stimuli at slightly different frequencies, we have referred to this class of phenomena as spontaneous sidebanding. It is invariably noted that the sideband spacing frequency appears to be a whole number fraction (1/J) of the operating speed which suggests that the wave form is periodic and completes a full cycle every J rotations of the rotor. Using a numerical model of a rotor which simulates local contact with a stator in close proximity as a bilinear spring, several studies have been carried out to explore the circumstances for this spontaneous sidebanding. Two general classes of this type of response have been found in systems that are effectively single-degree-of-freedom: (A) For highly nonlinear systems, the chaotic-like response in transition zones between successive orders of subharmonic and superharmonic operation is actually periodic, with a repetition index (J), and results in spontaneous sidebands clustered around the key subharmonic or superharmonic frequencies. No systematic relationship has been determined for the value of (J). (B) In transcritical operation of highly nonlinear and very lightly damped systems, a major sideband frequency spike is noted at a frequency which is approximately the system’s natural frequency. Recognition of this fact permits a simple estimate of the repetition index (J). All these observations from operation of the numerical model have been compared with experimental data derived from incidents of spontaneous sidebanding on aircraft gas turbine rotors. Excellent qualitative agreement has been found in most instances.
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Li, Chang He, Sheng Wang, and Yu Cheng Ding. "Analysis of Unbalanced Response for Coupled Double-Rotor Spindle System of High Speed Grinder." Key Engineering Materials 522 (August 2012): 383–87. http://dx.doi.org/10.4028/www.scientific.net/kem.522.383.
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This study was focused on the theoretical modeling and numerical simulation about the unbalanced response for coupled double-rotor spindle system of high speed grinder. Based on the rotor dynamics, a theoretical model was established using the transfer matrix method. The moment balance equations, and the transition matrix, the state vector, field matrix of coupled double-rotor spindle system of high speed grinder were analyzed and calculated. The numerical results showed that the amplitude of unbalance response increased by the same multiple as that of the amount of unbalance at different locations and at different speeds. Furthermore, the position most sensitive to the unbalance was the front end of rotor 2, followed by the middle and back end of rotor 2. Rotor 2 was especially sensitive to unbalance. Moreover, the vibration amplitudes of the front end, front and back bearings of rotor 1 increased in response to unbalanced increase of rotate speed. The vibration amplitude abruptly increased at 17500r/min corresponding to first-order critical speed.
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Wang, Longkai, Yijun Yin, Ailun Wang, Xing Heng, and Miao Jin. "Dynamic Modeling and Vibration Characteristics for a High-Speed Aero-Engine Rotor with Blade Off." Applied Sciences 11, no. 20 (October 17, 2021): 9674. http://dx.doi.org/10.3390/app11209674.
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Blade off that occurs during operation will generate a sudden imbalance excitation and make the rotor become inertially asymmetric, which leads to large instantaneous impact load and induces more complex rotor dynamic phenomena. In order to study the transient dynamic characteristics for complex rotors suffering from blade off, a mathematical model for solving the response of the gas generator rotor in the aero-turboshaft engine is established based on the FE method and DOF condensation, in which the complex structural characteristics, transient impact load, and inertia asymmetry of the rotor are considered. The complex impeller structure is modeled by piecewise linear fitting with cylindrical beam elements and tapered beam elements. Without loss of generality, the modeling method suitable for complex rotors is verified through a general complex test rotor with modal experiments. Based on this, the responses are solved for carrying out parametric studies and an understanding of the transient dynamic characteristics of the rotor under the extreme working conditions of blade off. The results show that the blade off has a great impact effect on the time-domain waveform, frequency components, and rotor orbits. At the instantaneous stage after blade off, the complex motion is composed of synchronous motion and some lower-order natural modes excited by blade off. Although the transient responses with blade off at different rotational speeds have similar time-varying characteristics, the impact factor is sensitive to the rotating speed. Most important is that the parameter of the blade off location will not only have a significant effect on the impact factor, but also on the frequency spectrum. These dynamic characteristics as well as impact effect provide certain guidance for the fault recognition and dynamic analysis to these complex rotors suffering blade off.
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Whalley, R., M. Ebrahimi, and A. Abdul-Ameer. "High-speed rotor-shaft systems and whirling identification." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 221, no. 6 (June 1, 2007): 661–76. http://dx.doi.org/10.1243/0954406jmes314.
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The transverse vibrations of shaft-rotor systems are considered. Interconnected assemblies of distributed parameter, compliant shafts, pointwise lumped rotor, and isentropic bearing units, are investigated. Analysis methods for shaft-rotor systems are formulated from the truncated, series expansion, of the rotor model, impedance matrix elements. Frequency domain evaluation of the determinant of the matrix model, enabling accurate validation, is incorporated. An illustrative application for a high speed, turbo-charger rotor system model is presented. Critical whirling speed conditions are identified. Alternative, established whirling speed evaluation techniques are investigated. Analysis, modelling accuracy, and the computational integrity of the procedures employed are emphasized.
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Bartlett, H., and R. Whalley. "Distributed rotor dynamics." Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 212, no. 4 (June 1, 1998): 249–65. http://dx.doi.org/10.1243/0959651981539442.
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The modelling, simulation and analysis of powered rotors with ‘long’ thin shells is investigated. General results enabling the prediction of the torsional vibrational signature of high-speed assemblies under acceleration or braking conditions are outlined. It is demonstrated that simulated response characteristics can be easily obtained and the effect of varying the rotor geometry can be routinely accommodated. Finally, a rotor for a high-speed paper manufacturing unit is investigated and the torsional behaviour of the assembly is computed. The volatile transient conditions presented are commented upon.
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Kosmynin, Alexander V., Vladimir S. Shchetinin, Sergey M. Kopytov, Alexander V. Ulianov, and Alexander S. Khvostikov. "IMPROVING ROTOR SHAFTS' ROTATIONAL ACCURACY IN HIGH-SPEED ROTOR SYSTEMS." Scholarly Notes of Komsomolsk-na-Amure State Technical University 1, no. 15 (September 30, 2013): 47–51. http://dx.doi.org/10.17084/2013.iii-1(15).8.
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Deng, Wangqun, Chao Fu, and Cong Yue. "Research on Transient High-Speed Dynamical Balancing of Power Turbine Rotor." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 36, no. 2 (April 2018): 375–81. http://dx.doi.org/10.1051/jnwpu/20183620375.
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A novel transient high-speed flexible rotor balancing method is derived and the transient run-up response information based balance method is used to balance a power turbine rotor of turboshaft engine. The balance efficiency is studied systematically to prove its robustness under two disturbance factors, i.e., random disturbed rotating speed and noise polluted vibration signal. Results show that the transient balance method can achieve satisfactory balance efficiency on real rotors. The disturbances have influence on the identification accuracy of the equivalent unbalance, but the robustness is good on most cases and it is a suitable technology for real applications.
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Liu, Yongmeng, Yingjie Mei, Chuanzhi Sun, Pinghuan Xiao, Ruirui Li, Xiaoming Wang, and Chengtian Li. "Multistage Asymmetric Rotors Coaxial Measurement Stacking Method Based on Minimization of Exciting Force." Symmetry 13, no. 6 (June 11, 2021): 1054. http://dx.doi.org/10.3390/sym13061054.
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The unbalanced exciting force of high-speed rotary asymmetric rotor equipment is the main factor causing rotor vibration. In order to effectively suppress the vibration of the asymmetric rotor equipment, the paper establishes a multistage asymmetric rotor coaxial measurement stacking method that minimizes the exciting force. By analyzing the propagation process of the centroid of the multistage asymmetric rotor assembly and analyzing the relationship between the geometric center and the centroid of a single asymmetric rotor, a multistage asymmetric unbalanced rotor propagation model based on geometric center stacking is established. The genetic algorithm is used to optimize the unbalance of the multistage asymmetric rotors. Combined with the vibration principle under the exciting force, the vibration amplitude of the left bearing at different rotation speeds under the minimization of the exciting force and the random assembly phase is analyzed. Finally, the experimental asymmetric rotors are dynamically measured, combined with the asymmetric rotors’ geometric error measurement experiment. The experimental results confirm that the vibration amplitude of the assembly phase with the minimum exciting force is smaller than the vibration amplitude under the random assembly phase at three-speed modes, and the optimization rate reached 73.2% at 9000 rpm, which proves the effectiveness of the assembly method in minimizing the exciting force.
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Wadia, A. R., and W. W. Copenhaver. "An Investigation of the Effect of Cascade Area Ratios on Transonic Compressor Performance." Journal of Turbomachinery 118, no. 4 (October 1, 1996): 760–70. http://dx.doi.org/10.1115/1.2840932.
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Transonic compressor rotor performance is highly sensitive to variations in cascade area ratios. This paper reports on the design, experimental evaluation, and three-dimensional viscous analysis of four low-aspect-ratio transonic rotors that demonstrate the effects of cascade throat area, internal contraction, and trailing edge effective camber on compressor performance. The cascade throat area study revealed that tight throat margins result in increased high-speed efficiency with lower part-speed performance. Stall line was also improved slightly over a wide range of speeds with a lower throat-to-upstream capture area ratio. Higher internal contraction, expressed as throat-to-mouth area ratio, also results in increased design point peak efficiency, but again costs performance at the lower speeds. Reducing the trailing edge effective camber, expressed as throat-to-exit area ratio, results in an improvement in peak efficiency level without significantly lowering the stall line. Among all four rotors, the best high-speed efficiency was obtained by the rotor with a tight throat margin and highest internal contraction, but its efficiency was the lowest at part speed. The best compromise between high-speed and part-speed efficiency was achieved by the rotor with a large throat and a lower trailing edge effective camber. The difference in the shock structure and the shock boundary layer interaction of the four blade was analyzed using a three-dimensional viscous code. The analytical results are used to supplement the data and provide further insight into the detailed physics of the flow field.
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Li, C. H., Z. R. Liu, Y. Zhou, and Y. C. Ding. "Investigation on Critical Speed and Vibration Mode of High Speed Grinder." Noise & Vibration Worldwide 42, no. 10 (November 2011): 47–54. http://dx.doi.org/10.1260/0957-4565.42.10.47.
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The influences of the grinder spindle's major structural parameters on its vibration mode were investigated. Based on the transfer-matrix method and taking into consideration the gyroscopic couple, the shear, the variable cross-section and other influential factors, a dynamic model was established for the multi-disk rotor of the rotor-bearing system of the grinder spindle. The critical speeds of first three orders, the modes of variation and other dynamic characteristic parameters of the grinder spindle were programmed and calculated. The influences of the axial pre-tightening force of the bearing, the span of the fulcrum bearing as well as the changes in the front and rear overhangs on the critical speed of the rotor-bearing system on the grinder spindle and their pattern of changes were analyzed. The results showed that the working speed of the spindle system is much lower than the primary critical speed and can therefore stay away the resonance range effectively.
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Xing, Jun Qiang, Lei Chen, Qi Zhang, and Yun Fei Ma. "Design and Analysis of Fan-Cooling for High Speed Permanent Magnet Machine Rotor." Advanced Materials Research 591-593 (November 2012): 3–6. http://dx.doi.org/10.4028/www.scientific.net/amr.591-593.3.
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Compared with common permanent magnet (PM) machine, the high speed PM machine has smaller size and larger power density. However, owing to high-speed high frequency and small volume, the PM rotor is more easily to become overheated so that irreversible demagnetization of the PM is induced. Traditional cooling methods of machine directly cool the machine stator, the temperature rise of rotor is reduced through heat exchange among stator, air gap and rotor. Owing to rapid temperature rise of high speed PM machine rotor, the method of indirect cooling rotor does not effectively protect PM rotor from overheating. To directly reduce the temperature rise of PM rotor and the volume of machine, design method of fan-cooling for high speed PM machine rotor is proposed in this paper, that is, high speed axial fan rotating synchronously with the high speed PM machine rotor is designed. Finally, the temperature rise of high speed PM machine rotor with the structure of high speed axial fan is analyzed based on the coupling method of fluid-solid, the validity is verified.
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Ling, J., and Y. Cao. "Improving Traditional Balancing Methods for High-Speed Rotors." Journal of Engineering for Gas Turbines and Power 118, no. 1 (January 1, 1996): 95–99. http://dx.doi.org/10.1115/1.2816556.
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This paper introduces frequency response functions, analyzes the relationships between the frequency response functions and influence coefficients theoretically, and derives corresponding mathematical equations for high-speed rotor balancing. The relationships between the imbalance masses on the rotor and frequency response functions are also analyzed based upon the modal balancing method, and the equations related to the static and dynamic imbalance masses and the frequency response function are obtained. Experiments on a high-speed rotor balancing rig were performed to verify the theory, and the experimental data agree satisfactorily with the analytical solutions. The improvement on the traditional balancing method proposed in this paper will substantially reduce the number of rotor startups required during the balancing process of rotating machinery.
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Ehrich, F. F. "High Order Subharmonic Response of High Speed Rotors in Bearing Clearance." Journal of Vibration and Acoustics 110, no. 1 (January 1, 1988): 9–16. http://dx.doi.org/10.1115/1.3269488.
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Subharmonic vibration refers to the response of a dynamic system to excitation at a whole-number multiple (n) of its natural frequency by vibrating asynchronously at its natural frequency, that is, at (1/n) of the excitation. The phenomenon is generally associated with asymmetry in the stiffness vs. deflection characteristic of the system. It may be characterized as the “bouncing” of the rotor on the surface of the stiff support, energized by every nth unbalance impulse prior to contact. Second, third and fourth order subharmonic vibration responses have previously been observed in high speed rotating machinery with such an asymmetry in the bearing supports. An incident is reported where 8th and 9th order subharmonic vibration responses have been observed in a high speed rotor. A simple but exact computer model of the phenomenon has been evolved based on the numerical integration of a finite difference formulation. Response curves and wave forms of rotor deflection at individual speeds are computed. It is shown that the response is a series of pseudo-critical peaks at whole-number multiples of the rotational speed. Very high orders of subharmonic vibration are found to be possible for systems with low damping and extreme nonlinearity.
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Sharma, P. B., Y. P. Jain, and D. S. Pundhir. "A Study of Some Factors Affecting the Performance of a Contra-Rotating Axial Compressor Stage." Proceedings of the Institution of Mechanical Engineers, Part A: Power and Process Engineering 202, no. 1 (February 1988): 15–21. http://dx.doi.org/10.1243/pime_proc_1988_202_003_02.
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An experimental investigation of the performance of a contra-rotating stage is reported. The influence of factors such as speed ratio of the two rotors, rotor stagger, pitch-chord ratio and axial spacing between the rotors is examined from tests on a 0.66 hub-tip ratio compressor. The study reveals that the performance of a contra-rotating stage is affected by all these factors. Axial spacing between the rotors and the speed ratio of the rotors both exhibit a strong influence on the stalling behaviour of the stage. It has been found that in a stage with close axial gap, rotating stall on the first rotor is suppressed if the second rotor is contra-rotated at a speed 50 per cent faster than the first rotor. This unique advantage of contra-rotation is not obtained if the axial gap is large. Measurements of sound pressure level are also reported to highlight the high noise problems associated with a contra-rotating stage.
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Whittingham, M. Stanley. "Electrical Energy Storage Using Flywheels." MRS Bulletin 33, no. 4 (April 2008): 419–20. http://dx.doi.org/10.1557/mrs2008.83.
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Flywheel energy storage systems use the kinetic energy stored in a rotor; they are often referred to as mechanical batteries. On charging, the fywheel is accelerated, and on power generation, it is slowed. Because the energy stored is proportional to the square of the speed, very high speeds are used, typically 20,000–100,000 revolutions per minute (rpm). To minimize energy loss due to friction, the rotors are spun in a vacuum and use magnetic bearings. The rotors today are typically made of high-strength carbon composites. One of the main limits to fywheels is the strength of the material used for the rotor: the stronger the rotor, the faster it can be spun, and the more energy it can store.
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Wang, S., and A. Seireg. "Whirl of High-Speed Rotors Driven by Dry or Lubricated Rollers." Journal of Mechanisms, Transmissions, and Automation in Design 107, no. 2 (June 1, 1985): 312–19. http://dx.doi.org/10.1115/1.3258725.
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This paper presents a computer-based simulation of the vibration and dynamic load conditions in rotors driven by dry or lubricated Hertzian contacts. The effect of clearance coefficient of friction, elastohydrodynamic film, number of drive rollers, and contact compliance on the rotor movement and the contact forces is investigated.
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Xiang, Hui Yu, Bao An Han, Chong Jie Leng, and Yan Jue Gong. "Modal Analysis of High-Speed Traction Motor Rotor Shaft." Advanced Materials Research 562-564 (August 2012): 1040–43. http://dx.doi.org/10.4028/www.scientific.net/amr.562-564.1040.
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Being one of the key parts in high-speed traction motor ,rotor shaft has a great influence on the dynamic characteristics of high-speed traction motor. This paper uses the UG to establish a simplified model of high-speed traction motor rotor shaft. The modal parameters were calculated and its inherent frequency characteristics were investigated with the analysis software MSC.Nastran. And we also analyze and calculate the foregoing five model shape of high-speed traction motor rotor shaft. These can provide a basis for the optimization design of high-speed traction motor rotor shaft and its dynamics analysis.
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Song, Ke, Huiting Huan, and Yuchi Kang. "Aerodynamic Performance and Wake Characteristics Analysis of Archimedes Spiral Wind Turbine Rotors with Different Blade Angle." Energies 16, no. 1 (December 29, 2022): 385. http://dx.doi.org/10.3390/en16010385.
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Continuous improvement of wind turbines represent an effective way of achieving green energy and reducing dependence on fossil fuel. Conventional lift-type horizontal axis wind turbines, which are widely used, are designed to run under high wind speed to obtain a high efficiency. Aiming to use the low-speed wind in urban areas, a novel turbine, which is called the Archimedes Spiral Wind Turbine (abbreviated as ASWT), was recently proposed for low-speed wind applications. In the current work, a numerical simulation on the five ASWT rotors with different blade angles was carried out, which were performed to predict the detailed aerodynamic performance and wake characteristics. The results show that the ASWT rotor with a large blade angle has a wider operating tip speed ratio range and a higher tip speed ratio point of maximum power coefficient within a certain range, and yet the ASWT rotor with the larger blade angle has a higher thrust coefficient. Additionally, the ASWT rotor with a large blade angle usually has a large power coefficient and thrust coefficient fluctuation amplitude. On the other hand, the ASWT rotor with a small blade angle permits the undisturbed free stream to pass through the rotor blades more easily than that with a large blade angle. This causes a stronger blockage effect for the ASWT rotor with a large blade angle. Moreover, the blade angle also has a great effect on the shape of the vortex structure. The blade tip vortex of the fixed-angle ASWT rotors is more stable than those of the variable-angle ASWT rotors. The hub vortex of the ASWT rotors with a large blade angle is stronger than those with a small blade angle. Meanwhile, the wake recovery for ASWT rotors with a small blade angle is evidently lower than those with a large blade angle.
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Chang, Seung Hwan, Dai Gil Lee, and Jin Kyung Choi. "Composite rotor for high-speed induction motors." Composite Structures 50, no. 1 (September 2000): 37–47. http://dx.doi.org/10.1016/s0263-8223(00)00068-4.
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Vankov, Alexei A., Vladimir S. Shchetinin, and Alexander V. Kosmynin. "DESCRIPTION OF THE HIGH-SPEED ROTOR DYNAMICS." Scholarly Notes of Komsomolsk-na-Amure State Technical University 1, no. 33 (March 26, 2018): 76–79. http://dx.doi.org/10.17084/ii-1(33).10.
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Khulief, Y. A., M. A. Mohiuddin, and M. El-Gebeily. "A New Method for Field-Balancing of High-Speed Flexible Rotors without Trial Weights." International Journal of Rotating Machinery 2014 (2014): 1–11. http://dx.doi.org/10.1155/2014/603241.
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Flexible rotor balancing, in general, relies to a great extent on physical insight into the modal nature of the unbalance response. The objective of this investigation is to develop a hybrid experimental/analytical technique for balancing high-speed flexible rotors. The developed technique adopts an approach that combines the finite element modeling, experimental modal analysis, vibration measurements, and mathematical identification. The modal imbalances are identified and then transformed to the nodal space, in order to determine a set of physical balancing masses at some selected correction planes. The developed method does not rely on trial runs. In addition, the method does not require operating the supercritical rotor in a high-speed balancing facility, while accounting for the contribution of higher significant modes. The developed scheme is applied to a multidisk, multibearing, high-speed flexible rotor, where the interaction between the rotor-bending operating deflections and the forces resulting from the residual unbalance are appreciable. Some new benchmark solutions and observations are reported. The applicability, reliability, and challenges that may be encountered in field applications are addressed.
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Zhang, Xiu Hua, Xue Feng Zhao, and Xing Lei Zhang. "Analysis of High-Speed Energy-Storing Flywheel Rotor." Applied Mechanics and Materials 214 (November 2012): 249–53. http://dx.doi.org/10.4028/www.scientific.net/amm.214.249.
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Appropriate rotor material and reasonable structure should be used for increase energy-storing density of flywheel. Theoretical analysis and design to high-speed energy-storing flywheel rotor with maximum energy-storing density is studied in the paper．The ratio of inner diameter and outer diameter and structure dimensions of a given condition flywheel rim is obtained by calculating. And the interference fit of rim/hub of the flywheel is analyzed with finite element software. One efficient and reliable calculating foundation and analysis method for the structure design of the flywheel rotor is provided.
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He, Tianran, Ziqiang Zhu, Fred Eastham, Yu Wang, Hong Bin, Di Wu, Liming Gong, and Jintao Chen. "Permanent Magnet Machines for High-Speed Applications." World Electric Vehicle Journal 13, no. 1 (January 7, 2022): 18. http://dx.doi.org/10.3390/wevj13010018.
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This paper overviews high-speed permanent magnet (HSPM) machines, accounting for stator structures, winding configurations, rotor constructions, and parasitic effects. Firstly, single-phase and three-phase PM machines are introduced for high-speed applications. Secondly, for three-phase HSPM machines, applications, advantages, and disadvantages of slotted/slotless stator structures, non-overlapping/overlapping winding configurations, different rotor constructions, i.e., interior PM (IPM), surface-mounted PM (SPM), and solid PM, are summarised in detail. Thirdly, parasitic effects due to high-speed operation are presented, including various loss components, rotor dynamic and vibration, and thermal aspects. Overall, three-phase PM machines have no self-starting issues, and exhibit high power density, high efficiency, high critical speed, together with low vibration and noise, which make them a preferred choice for high-performance, high-speed applications.
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Leong, Foo-Hong, Nan-Chyuan Tsai, and Hsin-Lin Chiu. "Infinite-stage magnetic clutch for shaft speed amplification." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 231, no. 1 (August 9, 2016): 193–204. http://dx.doi.org/10.1177/0954406215616654.
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An innovative design of magnetic coupler for shaft speed amplification is proposed and verified by experiments. The structure of proposed magnetic coupler is similar to an infinite-stage gearbox. In addition, the mathematical model of flux density is derived to look into the equation of adjustable gear ratio and effect of speed amplification. Moreover, two sets of experiments, namely verification of gear ratio and observation of stall phenomenon, are built up to examine the capability and drawback of the proposed variable-gear-ratio magnetic coupler. Three types of gear ratio are presented by theoretically analysis at first and then examined by experiments. The gear ratios for these three specific types between the input and output rotors are 4.75, 5.75, and 10.5, respectively. That is, the rotational speed of the output rotor can be precisely and realistically amplified. Besides, in order to reduce the torque inertia of outer rotor, a ferrite bush is inserted to the inner side of the core rotor to decrease the flux density at air gap. On the other hand, the overlapped area of permanent magnets, which are attached onto the inner rotor and outer rotor, has to be appropriately chosen. The smaller the overlapped area, the weaker is the magnetic attractive force at air gap. As long as these two modifications (an inserted ferrite bush and the aforesaid overlapped area) are validated, the torque inertia of outer rotor can be significantly reduced. Accordingly, the required power to rotate the outer rotor can be greatly reduced if the overlapped depth is shortened. However, insufficient overlapped depth between the high-speed rotor and low-speed rotor will bring about stall phenomenon caused by the magnetic attractive force between the high-speed rotor and the low-speed rotor being weaker than the start-up torque inertia. In other words, the reduced overlapped depth can also reduce the start-up torque inertia but stall phenomenon may easily occur relatively.
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Etemad, M. R., K. Pullen, C. B. Besant, and N. Baines. "Evaluation of Windage Losses for High-Speed Disc Machinery." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 206, no. 3 (August 1992): 149–57. http://dx.doi.org/10.1243/pime_proc_1992_206_025_02.
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Design and development of experimental apparatus is detailed for stator drag torque measurement as well as a method to evaluate rotor windage losses directly from air mass flow and temperature changes. Effects of air jets at the rotor rim were also investigated. Results are presented for air windage losses associated with ultra-high-speed machinery. These show that within the range investigated the air gap length between the rotor and the stator has an insignificant effect on windage losses. The lowest windage losses were encountered when air was forced through the rotor/stator gap from the direction of rim to bore.
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Hussain, Tanveer, Farooq Ahmed Arain, and Zulfiqar Ali Malik. "Use of Taguchi Method and Grey Relational Analysis to Optimize Multiple Yarn Characteristics in Open-End Rotor Spinning." Autex Research Journal 17, no. 1 (March 1, 2017): 67–72. http://dx.doi.org/10.1515/aut-2015-0046.
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Abstract Rotor speed and twist per metres (tpm) are two key parameters in open-end rotor spinning of cotton yarns. High spinning productivity can be obtained by keeping the rotor speed high and twist level as low as possible. However, too high rotor speed may result in yarn imperfections and too low twist level may result in lower tenacity yarns. This study aimed at optimising the multiple yarn characteristics in open-end rotor spinning using the Taguchi method and the grey relational analysis. Cotton yarn samples of 30 tex were produced on rotor spinning machine with different twist levels (i.e. 500, 550, 600 and 700 tpm) at different rotor speeds (i.e. 70,000, 80,000, 90,000 and 100,000 rpm) according to the Taguchi design of experiment. Optimal spinning process parameters were determined using the grey relational grade as the performance index. It was concluded that for the cotton fibres and yarn count used in this study, optimum properties of the yarns could be obtained at 90,000 rpm rotor speed and 700 tpm.
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Wu, Jingbo, Yongwei Wang, and Zhijun Guo. "Hybrid Pulse High-Frequency Voltage Injection Control Algorithm of Sensorless IPMSM for Vehicles." Computational Intelligence and Neuroscience 2022 (September 9, 2022): 1–9. http://dx.doi.org/10.1155/2022/4248643.
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A hybrid pulse vibration high-frequency voltage signal injection method is proposed to solve the problems that the conventional sensorless control algorithm of vehicle IPMSM may generate a large estimated rotor position error and opposite directions in identifying the polarity of magnetic poles under zero-speed and high-torque starting and low-speed operation. The magnetic pole polarity is identified by the saturation effect of the flux chain by injecting a high-frequency sinusoidal voltage signal and opposite pulse voltage signal into the axis d ^ of the assumed coordinate system simultaneously. Subsequently, the position relationship between the assumed d ^ axis and the actual d axis is studied in accordance with the amplitude of response current to acquire the rotor position and speed information. The simulation and experimental results suggest that the algorithm is capable of accurately identifying the magnetic pole polarity and estimating the rotor position at zero speed and low speeds, starting the motor smoothly at zero speed, and then operating the motor stably at low speeds.
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Wang, Ji Qiang, and Feng Xiang Wang. "Rotor Design for High Speed PM Machine Based on Riccati Transfer Matrix Method." Advanced Materials Research 383-390 (November 2011): 337–43. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.337.
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The rotor under study is a PM rotor of a synchronous machine intended for operation at 60 000 rpm. It is well known that design of high speed permanent magnetic (PM) rotor is quite different from that of a normal PM rotor. The determination of the rotor structure and dimensions must take consideration of the strength, stiffness and the magnetic properties of the PM rotor. Based on the Riccati transfer method, the dynamic model of the rotor-bearing system has been established. Then the supporting stiffness of the magnetic bearing is estimated and the PM rotor’s critical speeds and the corresponding vibration modes have been found. A prototype has been built and some test results proved the correct of the calculation.
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Ran, Shaolin, Yefa Hu, Huachun Wu, and Xin Cheng. "Active vibration control of the flexible high-speed rotor with magnetic bearings via phase compensation to pass critical speed." Journal of Low Frequency Noise, Vibration and Active Control 38, no. 2 (December 18, 2018): 633–46. http://dx.doi.org/10.1177/1461348418819404.
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In modern industries, high-speed motors and generators have received great attention, and they are widely used in micro turbine, centrifugal compressor, blower, etc. However, the resonance vibration of flexible rotor will become a challenging issue when the rotor has to operate above the first bending critical speed. In this paper, a phase compensation method is proposed to improve the damping level of the flexible rotor around the first bending critical speed. The dynamic characteristics of the flexible rotor are analyzed, and the modal frequency is obtained. The rotor finite element model is verified by the modal test. Based on Proportion-Integration-Differentiation (PID) controller, the phase of the control system is shaped with different general filters to improve the damping level of the flexible rotor around the first bending critical speed. The simulation and experimental results indicate that the first bending mode damping of rotor is obviously enhanced by phase compensation. The phase compensation method can effectively suppress the resonance vibration of the rotor and make the rotor smoothly pass the first bending critical speed, achieving supercritical operation.
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Van Zante, Dale E., John J. Adamczyk, Anthony J. Strazisar, and Theodore H. Okiishi. "Wake Recovery Performance Benefit in a High-Speed Axial Compressor." Journal of Turbomachinery 124, no. 2 (April 1, 2002): 275–84. http://dx.doi.org/10.1115/1.1445793.
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Rotor wakes are an important source of loss in axial compressors. The decay rate of a rotor wake is largely due to both mixing (results in loss) and stretching (no loss accrual). Thus, the actual loss associated with rotor wake decay will vary in proportion to the amounts of mixing and stretching involved. This wake stretching process, referred to by Smith (1996) as recovery, is reversible and for a 2-D rotor wake leads to an inviscid reduction of the velocity deficit of the wake. It will be shown that for the rotor/stator spacing typical of core compressors, wake stretching is the dominant wake decay process within the stator with viscous mixing playing only a secondary role. A model for the rotor wake decay process is developed and used to quantify the viscous dissipation effects relative to those of inviscid wake stretching. The model is verified using laser anemometer measurements acquired in the wake of a transonic rotor operated alone and in a stage configuration at near peak efficiency and near stall operating conditions. Results from the wake decay model exhibit good agreement with the experimental data. Data from the model and laser anemometer measurements indicate that rotor wake straining (stretching) is the primary decay process in the stator passage. Some implications of these results on compressor stage design are discussed.
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Fan, Na, Zhi Quan Deng, Xiao Yuan Chen, Yu Yang Mao, and Pei Lin Xu. "Speed Closed-Loop Control for Switched Reluctance Motor with Segmental Rotors Based on Angle Position Regulation." Advanced Materials Research 433-440 (January 2012): 6789–94. http://dx.doi.org/10.4028/www.scientific.net/amr.433-440.6789.
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This paper describes the structure and the magnetic circuit of switched reluctance motor with segmental rotors (SSRM), and presents the control strategy of speed closed-loop by regulating the turn-on angle of the main switches in the power converter based on PI algorithm. The turn-off angle is optimized according to different speeds of the motor. The deviation of the rotor speed is the input control parameter of PI controller, and the turn-on angle is the output control parameter. The strategy of current chopping control is used for comparing with angle position control when rotor speed is high. Both the simulation and experimental results show the well transient, steady performance and robustness of SSRM based on the angle position controller.
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Ma, Deji, Baozhi Tian, Xuejie Zheng, Yulin Li, Shibo Xu, and Ruilin Pei. "Study of High-Silicon Steel as Interior Rotor for High-Speed Motor Considering the Influence of Multi-Physical Field Coupling and Slotting Process." Materials 15, no. 23 (November 29, 2022): 8502. http://dx.doi.org/10.3390/ma15238502.
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Currently, high-speed motors usually adopt rotor structures with surface-mounted permanent magnets, but their sheaths will deteriorate performance significantly. The motor with interior rotor structure has the advantages of high power density and efficiency. At the same time, high silicon steel has low loss and high mechanical strength, which is extremely suitable for high-speed motor rotor core material. Therefore, in this paper, the feasibility of using high silicon steel as the material of an interior rotor high-speed motor is investigated. Firstly, the magnetic properties of high silicon steel under multi-physical fields were tested and analyzed in comparison with conventional silicon steel. Meanwhile, an interior rotor structure of high-speed motor using high silicon steel as the rotor core is proposed, and its electromagnetic, mechanical, and thermal properties are simulated and evaluated. Then, the experimental comparative analysis was carried out in terms of the slotting process of the core, and the machining of the high silicon steel rotor core was successfully completed. Finally, the feasibility of the research idea was verified by the above theoretical analysis and experimental characterization.
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Pan, Xin, Zhen Xie, Juan Lu, Haiqi Wu, Jinji Gao, and Zhinong Jiang. "Novel Liquid Transfer Active Balancing System for Hollow Rotors of High-Speed Rotating Machinery." Applied Sciences 9, no. 5 (February 26, 2019): 833. http://dx.doi.org/10.3390/app9050833.
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With the development of high-speed rotating machinery, the unbalance vibration feature of each rotor system has a greater influence on the work efficiency, bearing life, operational time, etc. Therefore, an active balancing system is necessary to automatically reduce the unbalance vibration in the process of rotor operation. This study introduced a novel liquid transfer active balancing system for the hollow rotors, and compensation mass was performed by balance liquid transmission between two pairs of contra-positioned chambers. The performance of this new balance actuator was analyzed, including balancing velocity, balancing accuracy, and the effect on rotor dynamics. A monitoring and control program was constructed to control the balance actuator. Two extraction methods of synchronic vibration were introduced and quantitatively compared through simulation. A control program was developed and the control accuracy was within 1 ms. Furthermore, the effectiveness of the new balancing system was verified through active balance experiments and the maximum speed was 15,600 rpm. The results indicate that the balancing system could effectively decrease the unbalance vibration of the rotor system within 10 s, and the amount of decrease was more than 80%.
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Freakley, P. K., and S. R. Patel. "Internal Mixing: A Practical Investigation of the Flow and Temperature Profiles during a Mixing Cycle." Rubber Chemistry and Technology 58, no. 4 (September 1, 1985): 751–73. http://dx.doi.org/10.5254/1.3536091.
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Abstract From the results of mixing trials with a highly instrumented BR Banbury and biconical rotor rheometry of mixed batches, a detailed analysis of flow and mixing characteristics in the region of a rotor wing has been undertaken. An ‘angled spreader blade’ analogy of the rotor wing is proposed as being a viable basis for mathematical modelling. A one-dimensional flow analysis is used, in which power-law flow behavior and isothermal conditions are assumed. Dispersive mixing, which depends on the stress levels generated during mixing, is shown to occur throughout the entire mass of material swept in front of the rotor wing and not simply at the rotor tip. In addition, the stress levels depend more strongly on batch temperature than on rotor speed. High rotor speeds tend to lead to reduced stress levels as a result of the associated rapid rise in batch temperature, although choosing an appropriate fill factor can minimize temperature rise by promoting efficient heat transfer to the cooling water. During each rotor revolution, the rotor wing collects a mass of material from the reservoir between the rotors. This mass of material is then progressively reduced by leakage flow under the rotor tip and flow around the end of the wing, until the revolution is completed by the return of a residue to the reservoir. The flow around the end of the rotor is shown to be consistently greater than the leakage flow, although the ratio can be influenced by both fill factor and rotor speed. At high rotor speeds and low fill factors, it appears that material is retained in the regions of the side frames of the mixer and may give batch inhomogeneity through poor distribution mixing.
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Halder, B., A. Mukherjee, and R. Karmakar. "Theoretical and Experimental Studies on Squeeze Film Stabilizers for Flexible Rotor-Bearing Systems Using Newtonian and Viscoelastic Lubricants." Journal of Vibration and Acoustics 112, no. 4 (October 1, 1990): 473–82. http://dx.doi.org/10.1115/1.2930131.
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A combination of a squeeze film damper and a plane journal bearing is studied as a stabilizing scheme. The damper is made to play the role of a stabilizer to postpone the instability threshold speeds of flexible rotors. Both Newtonian and viscoelastic fluids are used in the rotor-bearing system. Dynamics of the system is theoretically analyzed using bond graphs. Analysis reveals that the use of a Newtonian fluid in the stabilizer largely improves the high speed stability range. However, viscoelastic stabilizing fluid has a detrimental effect on highly flexible rotors. Experimental investigations, conducted on a flexible rotor (natural frequency, 30 Hz), confirm the theoretical findings. In addition, experiments indicate that though the use of viscoelastic stabilizing fluids leads to instability in flexible rotors, the growth of large amplitude whirl is postponed to very high speeds.
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Sankar, T. S., S. A. Ramu, and R. Ganesan. "Stochastic Finite Element Analysis for High Speed Rotors." Journal of Vibration and Acoustics 115, no. 1 (January 1, 1993): 59–64. http://dx.doi.org/10.1115/1.2930315.
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The general problem of the dynamic response of highspeed rotors is considered in which certain system parameters may have a spatial stochastic variation. In particular the elastic modulus and mass density of a rotating shaft are described through one dimensional stochastic field functions so that the imperfections in manufacture and measurement can be accounted for. The stochastic finite element method is developed so that the variability of the response of the rotor can be interpreted in terms of the variation of the material property. As an illustration the whirl speed analysis is performed to determine the stochastics of whirl speeds and modes through the solution of a random eigenvalue problem associated with a non self-adjoint system. Numerical results are also presented.
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Dvořák, Karel, Adéla Macháčková, Simona Ravaszová, and Dominik Gazdič. "Effect of Imposed Shear Strain on Steel Ring Surfaces during Milling in High-Speed Disintegrator." Materials 13, no. 10 (May 13, 2020): 2234. http://dx.doi.org/10.3390/ma13102234.
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This contribution characterizes the performance of a DESI 11 high-speed disintegrator working on the principle of a pin mill with two opposite counter-rotating rotors. As the ground material, batches of Portland cement featuring 6–7 Mohs scale hardness and containing relatively hard and abrasive compounds with the specific surface areas ranging from 200 to 500 m2/kg, with the step of 50 m2/kg, were used. The character of the ground particles was assessed via scanning electron microscopy and measurement of the absolute/relative increase in their specific surface areas. Detailed characterization of the rotors was performed via recording the thermal imprints, evaluating their wear by 3D optical microscopy, and measuring rotor weight loss after the grinding of constant amounts of cement. The results showed that coarse particles are ground by impacting the front faces of the pins, while finer particles are primarily milled via mutual collisions. Therefore, the coarse particles cause higher abrasion and wear on the rotor pins; after the milling of 20 kg of the 200 m2/kg cement sample, the wear of the rotor reached up to 5% of its original mass and the pins were severely damaged.
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Xavier Dias, Letícia Betânia, Pedro Afonso de Melo Queiroz, Thaís Cardoso de Castro, Marco Antonio Moreira de Freitas, Érica Fernandes Leão-Araújo, and Warley Marcos Nascimento. "Physiological quality of mechanically harvested chickpea seeds." Revista Engenharia na Agricultura - Reveng 29 (March 26, 2021): 28–35. http://dx.doi.org/10.13083/reveng.v29i1.10907.
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Our objective was to evaluate the occurrence of mechanical damage in chickpea seeds with the combination of two harvester speeds (2.5 and 3.5 km.h-1) and three adjustments for rotor rotation speeds (500, 700, and 850 rpm). Harvesting was carried out in a seed production field. Seeds were evaluated for purity, germination (G), first count (FC), germination speed index (GSI), hypochlorite, electrical conductivity, and tetrazolium tests. There was an effect of harvester speeds on seed physiological quality for the first count (FC), germination (G), germination speed index (GSI), especially when combining with high rotor rotation speed. In these cases, the speed of 2.5 km.h-1 resulted in lower values. This harvester speed also had worse results when combining with 850 rpm for purity and hypochlorite tests. The tetrazolium test was not efficient in identifying differences in seed quality. There was no significant interaction between harvester speeds and rotor rotation speeds for the conductivity test. Evaluating the harvester speed’s isolated effect (3.5 km.h-1), we identified problems in seed vigor due to the higher value of exudates in the electrical conductivity test. Low harvester speed (2.5 km.h-1) associated with high rotor rotation speeds (700 and 850 rpm) causes a reduction of the physical and physiological quality of seeds.
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Jiang, Yuening, Hai Li, and Hongguang Jia. "Aerodynamics Optimization of a Ducted Coaxial Rotor in Forward Flight Using Orthogonal Test Design." Shock and Vibration 2018 (May 28, 2018): 1–9. http://dx.doi.org/10.1155/2018/2670439.
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To investigate the aerodynamic complexities involved in the combination of freestream and propeller’s suction flow field of ducted coaxial rotors system in forward flight, an orthogonal L16(43) test design has been applied to optimize the design parameters including forward speed, pitch angle, and axial spacing between rotors. Multiblock grids and Multiple Frame of Reference (MFR) method are adopted for calculating aerodynamic performance of the system, hover characteristic was compared with experimental data obtained from the test stand, and the thrust performance is well predicted for various rotor spacing and a range of rpm. This solution approach is developed for the analytical prediction of forward flight and the simulation results indicated that the design parameters influenced lift, drag, and torque reduced in the order: wind speed > rotor spacing > pitch angle, wind speed > pitch angle, and rotor spacing > wind speed > pitch angle, respectively. The optimal rotor spacing and pitch angle were determined to maximize the aerodynamic performance considering high lift, low drag, and trimmed torque.