To see the other types of publications on this topic, follow the link: Model rotor.
Journal articles on the topic 'Model rotor'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Model rotor.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Muszynska, A. "Improvements in Lightly Loaded Rotor/Bearing and Rotor/Seal Models." Journal of Vibration and Acoustics 110, no. 2 (1988): 129–36. http://dx.doi.org/10.1115/1.3269489.
Full textAbstract:
A model for lightly loaded steadily rotating shaft/bearing/seal systems is proposed in this paper. The model is based on modal characteristics for the rotor, and rotational characteristics for the fluid dynamic forces generated in bearings and/or seals. The fluid average circumferential velocity ratio as a nonlinear function of shaft eccentricity represents a key factor in the model. The model is extremely useful for rotor stability analysis. The model adequacy was proved for one and two lateral mode models of rotors.
2
Muhammed Ameen, Yahya, and Jaafar Khalaf Ali. "Flexible rotor balancing without trial runs using experimentally tuned FE based rotor model." Basrah journal of engineering science 21, no. 1 (2021): 20–26. http://dx.doi.org/10.33971/bjes.21.1.4.
Full textAbstract:
A method based on experimentally calibrated rotor model is proposed in this work for unbalance identification of flexible rotors without trial runs. Influence coefficient balancing method especially when applied to flexible rotors is disadvantaged by its low efficiency and lengthy procedure, whilst the proposed method has the advantage of being efficient, applicable to multi-operating spin speeds and do not need trial runs. An accurate model for the rotor and its supports based on rotordynamics and finite elements analysis combined with experimental modal analysis, is produced to identify the unbalance distribution on the rotor. To create digital model of the rotor, frequency response functions (FRFs) are determined from excitation and response data, and then modal parameters (natural frequencies and mode shapes) are extracted and compared with experimental analogies. Unbalance response is measured traditionally on rotor supports, in this work the response measured from rotating disks instead. The obtained results show that the proposed approach provides an effective alternative in rotor balancing. Increasing the number of balancing disks on balancing quality is investigated as well.
3
Kong, Yong-Boon, J. V. R. Prasad, Lakshmi N. Sankar, and Chengjian He. "Finite State Inflow Flow Model for Coaxial Rotor Configuration." Journal of the American Helicopter Society 65, no. 3 (2020): 1–11. http://dx.doi.org/10.4050/jahs.65.032002.
Full textAbstract:
An analytical coaxial rotor inflow model has been developed from potential flow theory using the pressure potential superposition approach. The coaxial rotor pressure potential superposition inflow model (PPSIM) is formulated in statespace form with structure similar to the Peters–He model, except that additional off-diagonal blocks are included in the apparent mass (M-matrix) and influence coefficient matrices (L-matrix). These off-diagonal blocks take into account mutual interference effects present in a coaxial rotor system by relating the rotor's inflows due to other rotor's pressure loadings. Induced inflow distributions on both upper and lower rotors are computed using PPSIM for comparison against predictions from high-fidelity models such as GT-Hybrid and the viscous vortex particle method (VVPM). Good agreement between PPSIM-induced inflow results and GT-hybrid as well as VVPM data has been shown for hover flight condition. At low advance ratio, there are differences in fore-to-aft inflow states between PPSIM and the high-fidelity models. This is because PPSIM assumed rigid, skewed cylindrical wake geometries for both upper and lower rotors during forward flight. But in GT-Hybrid and VVPM, wake structures are allowed to move freely in space and are mainly affected by rotor-induced velocities at low advance ratios. Owing to the close proximity between upper and lower rotors, mutual interference-induced velocities significantly distorted the rotors' wake geometries. The rigid rotor wake geometry assumptions in PPSIM and the distortion captured in higher fidelity models are the reasons behind differences in rotor-induced inflows. At higher advance ratios, wake distortion effects are less prominent since free-stream inflows are significantly larger than rotorinduced velocities. Hence, smaller differences between PPSIM inflow states and those extracted from GT-Hybrid as well as VVPM are observed at high advance ratios.
4
Wang, Nanfei, Dongxiang Jiang, and Hongzhi Xu. "Dynamic characteristics analysis of a dual-rotor system with inter-shaft bearing." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, no. 3 (2017): 1147–58. http://dx.doi.org/10.1177/0954410017748969.
Full textAbstract:
The dual-rotor structure is susceptible to vibration, causing the malfunction of the entire operating system. In order to avoid the resonance during operation, it is significant and necessary to conduct modal analysis of such rotors. The dynamic analysis of the full dual-rotor system under operating conditions is also necessary to study dynamic characteristics of the rotating system. In this paper, one-dimension Timoshenko beam-type model, including the effects of gyroscopic moments, rotary inertias, bending and shear deformations, and three-dimension model for dual-rotor system with inter-shaft bearing are developed. Critical speed tests of dual-rotor are carried out to verify the analytical results. Based on the finite element models, the first critical speed excited by inner rotor and the first two critical speeds excited by outer rotor are calculated. The comparisons between both finite element models indicate that 1D model costs less time, which can be used to predict the critical speeds. Good agreement between the theoretical and experimental results shows the accuracy of the FE models. The Campbell diagram, critical speeds, operational deflection shapes and unbalance response of the dual-rotor are obtained to fully study the dynamic characteristics of the dual-rotor system.
5
Wang, Nanfei, Hongzhi Xu, and Dongxiang Jiang. "Dynamic Model and Fault Feature Research of Dual-Rotor System with Bearing Pedestal Looseness." Mathematical Problems in Engineering 2016 (2016): 1–18. http://dx.doi.org/10.1155/2016/3817405.
Full textAbstract:
The paper presents a finite element model of dual-rotor system with pedestal looseness stemming from loosened bolts. Dynamic model including bearing pedestal looseness is established based on the dual-rotor test rig. Three-degree-of-freedom (DOF) planar rigid motion of loose bearing pedestal is fully considered and collision recovery coefficient is also introduced in the model. Based on the Timoshenko beam elements, using the finite element method, rigid body kinematics, and the Newmark-βalgorithm for numerical simulation, dynamic characteristics of the inner and outer rotors and the bearing pedestal plane rigid body motion under bearing pedestal looseness condition are studied. Meanwhile, the looseness experiments under two different speed combinations are carried out, and the experimental results are basically the same. The simulation results are compared with the experimental results, indicating that vibration displacement waveforms of loosened rotor have “clipping” phenomenon. When the bearing pedestal looseness fault occurs, the inner and outer rotors vibration spectrum not only contains the difference and sum frequency of the two rotors’ fundamental frequency but also contains2Xand3Xcomponent of rotor with loosened support, and so forth; low frequency spectrum is more, containing dividing component, and so forth; the rotor displacement spectrums also contain fewer combination frequency components, and so forth; when one side of the inner rotor bearing pedestal is loosened, the inner rotor axis trajectory is drawn into similar-ellipse shape.
6
Peng, Jifeng. "Effects of Aerodynamic Interactions of Closely-Placed Vertical Axis Wind Turbine Pairs." Energies 11, no. 10 (2018): 2842. http://dx.doi.org/10.3390/en11102842.
Full textAbstract:
In this study, a numerical model was developed to study the effects of aerodynamic interactions between a pair of counter-rotating vertical axis wind turbines (VAWTs) in close proximity. In this model, the rotor rotation is not prescribed as a constant as in most other studies, but is determined by the moment of inertia and the total torque of the rotor, including the aerodynamic torque, generator torque, and a torque representing friction. This model enables study of the behavior of the rotor under an arbitrary ambient wind profile. The model was applied to an isolated rotor with five straight J-blades and pairs of identical rotors placed in close proximity. Compared with an isolated rotor, the aerodynamic interactions between the pair of rotors enhance the aerodynamic torques on the rotors and significantly increase the turbine power output on a per unit basis. The enhancement in turbine power output due to aerodynamic enhancement decreases with the distance between the pair of rotors.
7
Sun, Chuanzhi, Ruirui Li, Ze Chen, et al. "Research on Vibration Suppression Method Based on Coaxial Stacking Measurement." Mathematics 9, no. 12 (2021): 1438. http://dx.doi.org/10.3390/math9121438.
Full textAbstract:
A dynamic analysis model of the unbalanced vibration response of a single-rotor system is established to study the corresponding mechanism of the unbalanced excitation force and vibration response caused by the deviation of the rotor mass centroid in this paper, and finally to achieve the combined rotor vibration suppression. First, the installation of multi-stage rotors during vibration was studied, and the rotor mass centroid transfer model in the rotating coordinate system was established to obtain the unbalanced excitation force vectors of the rotors at all levels based on the traditional stacking assembly method and axiality measurement. Second, the rotor unbalance excitation force vectors were substituted at all levels to establish the finite element analysis model of the single-rotor system. Finally, a simulation analysis was carried out for the stacking assembly of the three-stage rotor, and the rotor test piece was used for the vibration experiment. The results show that the optimal assembly phase of the multi-stage rotor obtained by the dynamic analysis model of the unbalanced vibration response of the single-rotor system can effectively suppress the vibration of the combined rotor.
8
Shahmiri, Farid. "Twin-rotor hover performance examination using overlap tests." Aircraft Engineering and Aerospace Technology 89, no. 1 (2017): 155–63. http://dx.doi.org/10.1108/aeat-02-2015-0032.
Full textAbstract:
Purpose The aim of this paper was to experimentally examine twin-rotor hover performance for different rotor overlap ratios at practical rotor loading. Design/methodology/approach The methodology was formed based on data measurements for a designed twin-rotor test model and development of hover performance mathematical models. Thus, measurements were made using a central composite test plan, and then mathematical models for thrust power required power loading (PL) and figure of merit (FM) as functions of collective pitch tip speed; rotor overlap ratio was obtained. In the present paper, the test model consisted of two three-bladed rotors with a diameter of 220 mm and a blade aspect ratio of 16.05. The blades were of a rectangular planform with NACA 0012 cross sections and had no twist or taper. The model was built such that the rear rotor was fixed on the fuselage, and the front rotor could move longitudinally for tests up to about 40 per cent overlap ratio in hover. Findings The best hover aerodynamic efficiency (maximum PL of 14.6 kg/kW) was achieved for non-overlapped rotors at a low value of disc loading (DL) and also at FM of 0.6 at that DL. This result was in agreement with blade element momentum theory predictions. Practical implications Results for the twin-rotor test model can be generalized for actual tandem helicopters through the Reynolds number transformation technique and also some modifications. Originality/value Design and construction of the twin-rotor test model and experimental measurements of hover performance based on an optimal test plan were performed for the first time.
9
Guner, Feyyaz, and J. V. R. Prasad. "Combined Momentum Theory and Simple Vortex Theory Inflow Model for Multirotor Configurations." Journal of the American Helicopter Society 67, no. 2 (2022): 1–15. http://dx.doi.org/10.4050/jahs.67.022007.
Full textAbstract:
For conventional main/tail rotor helicopters, momentum theory-based inflow models are still popular for design trade studies and flight simulations. However, simple momentum theory-based inflow models are not readily applicable in design trade studies of multirotor configuration vehicles where complex flow interactions among rotors can have a significant impact on vehicle overall performance, and hence, can impact vehicle sizing. The use of empirically corrected ad hoc inflow models is not often satisfactory. In this study, momentum theory is combined with a simple vortex theory in the development of a combined momentum theory and simple vortex theory (CMTSVT) based inflow model that is readily applicable to generic multirotor configurations. The developed model is validated against some multirotor inflow models and experimental data from the literature through comparisons of inflow predictions and performance predictions for different dual-rotor configurations. Further, inflow predictions using the proposed inflow model for a partially overlapping quad-rotor configuration are presented to illustrate the significance of rotor-on-rotor flow interactions in multirotor vehicle configurations.
10
Povarov, Sergii. "Determination of the aerodynamic characteristics of the tiltrotor with the wingtip-mounted coaxial rotors." MECHANICS OF GYROSCOPIC SYSTEMS, no. 40 (December 26, 2021): 108–16. http://dx.doi.org/10.20535/0203-3771402020248778.
Full textAbstract:
The article describes the study of rotor-to-wing aerodynamic interaction for the wingtip-mounted coaxial rotors configuration of the tiltrotor aircraft.
 The influence of the rotor slipstreams on lift-to-drag ratio characteristic was determined. Obtained results were compared with similar characteristics of the equivalent in thrust conventional single rotor slipstreams impact.
 Using the computational aerodynamics methods (panel-vortex method) the flow around the tiltrotor model with the wingtip-mounted single and coaxial rotors has been simulated. A study of the basic model configuration with conventional single rotors, based on the technical characteristics of the AgustaWestland AW609 tiltrotor, was conducted. Further researches were conducted for a modified model where single rotors were replaced with equivalent in thrust coaxial rotors. The influence of the rotor slipstreams on the aerodynamic characteristics of the model for both directions of rotors rotation in coaxial combination is considered. Also, the dependence of the maximum lift-to-drag characteristic due to the coaxial rotor diameters change has been determined.
 The results show that the coaxial rotor slipstreams-to-wing aerodynamic interaction effect is the similar to the effect of conventional single rotor, but less intensive. Comparison of the results showed that a tiltrotor equipped with wingtip-mounted single rotors has approximately 20% greater maximum lift-to-drag characteristic than one equipped with coaxial rotors with the same thrust. However, the use of coaxial rotors allows getting higher maximum speed, when conventional single rotors lose the efficiency significantly. Therefore, it is advisable to conduct further research for the possibility of using coaxial rotors for tiltrotor aircrafts.
 The research results are presented in graphical form. The obtained data provides a basis for further studies of the described problem, and also will be useful for new tiltrotor design works.
11
Povarov, Sergey. "Comparison of aerodynamic characteristics of convertible models with single and coaxial schemes of propellers." MECHANICS OF GYROSCOPIC SYSTEMS, no. 39 (May 20, 2020): 96–105. http://dx.doi.org/10.20535/0203-3771392020229110.
Full textAbstract:
The article describes the study of rotor-to-wing aerodynamic interaction for the wingtip-mounted coaxial rotors configuration of the tiltrotor aircraft.
 The influence of the rotor slipstreams on lift-to-drag ratio characteristic was determined. Obtained results were compared with similar characteristics of the equivalent in thrust conventional single rotor slipstreams impact.
 Using the computational aerodynamics methods (panel-vortex method) the flow around the tiltrotor model with the wingtip-mounted single and coaxial rotors has been simulated. A study of the basic model configuration with conventional single rotors, based on the technical characteristics of the AgustaWestland AW609 tiltrotor, was conducted. Further researches were conducted for a modified model where single rotors were replaced with equivalent in thrust coaxial rotors. The influence of the rotor slipstreams on the aerodynamic characteristics of the model for both directions of rotors rotation in coaxial combination is considered. Also, the dependence of the maximum lift-to-drag characteristic due to the coaxial rotor diameters change has been determined.
 The results show that the coaxial rotor slipstreams-to-wing aerodynamic interaction effect is the similar to the effect of conventional single rotor, but less intensive. Comparison of the results showed that a tiltrotor equipped with wingtip-mounted single rotors has approximately 20% greater maximum lift-to-drag characteristic than one equipped with coaxial rotors with the same thrust. However, the use of coaxial rotors allows getting higher maximum speed, when conventional single rotors lose the efficiency significantly. Therefore, it is advisable to conduct further research for the possibility of using coaxial rotors for tiltrotor aircrafts.
 The research results are presented in graphical form. The obtained data provides a basis for further studies of the described problem, and also will be useful for new tiltrotor design works.
12
Yang, S.-C. "A mathematical model of the rotor profile of the single-screw compressor." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 216, no. 3 (2002): 343–51. http://dx.doi.org/10.1243/0954406021525052.
Full textAbstract:
This paper presents a method for determining the basic profile of a single-screw compressor including a gate rotor and a screw rotor. The inverse envelope concept for determining the cutting-edge curve of the gate rotor is presented. Based on this concept, the required cutter for machining the screw rotor can be obtained by an envelope of the one-parameter family of obtained screw rotors. The obtained screw rotor is an envelope of the family of gate rotor surfaces. Let the obtained envelope of the one-parameter family of gate rotor surfaces become the generating surface. The inverse envelope can be used to obtain the envelope of the family of generating surfaces. Then, the profile of the gate rotor with the cutting-edge curve can be easily obtained. The proposed method shows that the gate rotor and the screw rotor are engaged along the contact line at every instant. This is essential to reduce the effect of leakage on compressor performance. In this paper, a mathematical model of the meshing principle of the screw rotor with the gate rotor is established. As an example, the single-screw compressor for a compressor ratio of 11:6 is determined with the aid of the proposed mathematical model. Results from these mathematical models should have applications in the design of single-screw compressors.
13
Liu, Jingze, Qingguo Fei, Shaoqing Wu, Zhenhuan Tang, Sanfeng Liao, and Dahai Zhang. "An Efficient Dynamic Modeling Technique for a Central Tie Rod Rotor." International Journal of Aerospace Engineering 2021 (June 8, 2021): 1–11. http://dx.doi.org/10.1155/2021/6618828.
Full textAbstract:
Compared with the three-dimensional rotor model for a central tie rod rotor, an equivalent one-dimensional model can greatly improve the computational efficiency in rotor dynamics analysis with a certain accuracy. However, little research work can be found on improving the modeling accuracy of one-dimensional models using experimental data. In this paper, a one-dimensional discrete mass model considering pretightening force is proposed for central tie rod rotors to achieve the purpose of both efficient and accurate modeling. Experimental testing and three-dimensional model analysis are used as reference and verification approaches. A sensitivity-based method is adopted to update the proposed one-dimensional model via minimizing the error in the critical speed comparing with the corresponding three-dimensional finite element model which has been verified by a modal test. Prediction of damped unbalanced response is conducted to show the practicality of the updated one-dimensional model. Results show that the method presented in this research work can be used to simulate a complex preloaded rotor system with high efficiency and accuracy.
14
Tucker, V. A. "Using a Collision Model to Design Safer Wind Turbine Rotors for Birds." Journal of Solar Energy Engineering 118, no. 4 (1996): 263–69. http://dx.doi.org/10.1115/1.2871791.
Full textAbstract:
A mathematical model for collisions between birds and propellor-type turbine rotors identifies the variables that can be manipulated to reduce the probability that birds will collide with the rotor. This study defines a safety index—the “clearance power density”—that allows rotors of different sizes and designs to be compared in terms of the amount of wind energy converted to electrical energy per bird collision. The collision model accounts for variations in wind speed during the year and shows that for model rotors with simple, one-dimensional blades, the safety index increases in proportion to rotor diameter, and variable speed rotors have higher safety indexes than constant speed rotors. The safety index can also be increased by enlarging the region near the center of the rotor hub where the blades move slowly enough for birds to avoid them. Painting the blades to make them more visible might have this effect. Model rotors with practical designs can have safety indexes an order of magnitude higher that those for model rotors typical of the constant speed rotors in common use today. This finding suggests that redesigned rotors could have collision rates with birds perhaps an order of magnitude lower than today’s rotors, with no reduction in the production of wind power. The empirical data that exist for collisions between raptors, such as hawks and eagles, and rotors are consistent with the model: the numbers of raptor carcasses found beneath large variable speed rotors, relative to the numbers found under small constant speed rotors, are in the proportions predicted by the collision model rather than in proportion to the areas swept by the rotor blades. However, uncontrolled variables associated with these data prevent a stronger claim of support for the model.
15
Barkat, Ibtissem, Abdelouahab Benretem, Fawaz Massouh, Issam Meghlaoui, and Ahlem Chebel. "Modeling and simulation of forces applied to the horizontal axis wind turbine rotors by the vortex method coupled with the method of the blade element." International Journal of Power Electronics and Drive Systems (IJPEDS) 12, no. 1 (2021): 413. http://dx.doi.org/10.11591/ijpeds.v12.i1.pp413-420.
Full textAbstract:
This article aims to study the forces applied to the rotors of horizontal axis wind turbines. The aerodynamics of a turbine are controlled by the flow around the rotor, or estimate of air charges on the rotor blades under various operating conditions and their relation to the structural dynamics of the rotor are critical for design. One of the major challenges in wind turbine aerodynamics is to predict the forces on the blade as various methods, including blade element moment theory (BEM), the approach that is naturally adapted to the simulation of the aerodynamics of wind turbines and the dynamic and models (CFD) that describes with fidelity the flow around the rotor. In our article we proposed a modeling method and a simulation of the forces applied to the horizontal axis wind rotors turbines using the application of the blade elements method to model the rotor and the vortex method of free wake modeling in order to develop a rotor model, which can be used to study wind farms. This model is intended to speed up the calculation, guaranteeing a good representation of the aerodynamic loads exerted by the wind.
16
Zaytsev, Nikolay, Denis Zaytsev, Andrey Makarov, and Dmitriy Mineev. "NUMERICAL SIMULATION OF THE DYNAMICS OF A FLEXIBLE ROTOR WITH TWO BALL AUTO-BALANCERS." Perm National Research Polytechnic University Aerospace Engineering Bulletin, no. 62 (2020): 31–44. http://dx.doi.org/10.15593/2224-9982/2020.62.04.
Full textAbstract:
Ball auto-balancing devices can to compensate changes of unbalance "on the move" only for rotors operating at supercritical speeds. For automatic balancing of such rotors, classified as flexible rotors, several auto-balancers located in different cross sections of the shaft are necessary. This makes it necessary to account bending fluctuations on studies of dynamics of the rotor with auto-balancers, that is especially important in the design of the real rotors. In view of the complexity of experimental studies of such rotors in the article the method of direct numerical simulation of the dynamics of the flexible rotor system – supports – auto-balances is considered. The methodological basis of this method is the use of a discrete multi-mass rotor model, which is equivalent in dynamic characteristics to a real rotor, and also the equations of dynamics of the system discrete rotor – supports – auto-balancers, obtained in the direct form of recording. For definition of discrete masses and a matrix of coefficients of influence of stiffness of rotor cross-sections it is supposed to use calculations for finite-element model of a real rotor by existing software complexes of the engineering analysis. The mathematical model of the system dynamics obtained by the Lagrange method takes into account the non-stationarity of the rotor rotation speed, the influence of gravity and the rolling friction of the balls in the auto-balancer cages. Verification of the mathematical model was performed by reproducing the published data using a computational model for a two-support single-disk three-mass rotor with a two-ball auto-balancer. For a four-mass rotor with two two-ball auto-balancers, the results of numerical simulation of dynamics for the modes of acceleration, steady-state rotation and deceleration are presented. It is shown that for the system under consideration, only partial auto-balancing takes place in the steady rotation mode, including after a stepwise increase of the imbalance.
17
Fletcher, T. M., and R. E. Brown. "Modelling the interaction of helicopter main rotor and tail rotor wakes." Aeronautical Journal 111, no. 1124 (2007): 637–43. http://dx.doi.org/10.1017/s0001924000004814.
Full textAbstract:
Abstract The mutual interaction between the main rotor and tail rotor wakes is central to some of the most problematic dynamic phenomena experienced by helicopters. Yet achieving the ability to model the growth and propagation of helicopter rotor wakes with sufficient realism to capture the details of this interaction has been a significant challenge to rotorcraft aerodynamicists for many decades. A novel computational fluid dynamics code tailored specifically for rotorcraft applications, the vorticity transport model, has been used to simulate the interaction of the rotors of a helicopter with a single main rotor and tail rotor in both hover and low-speed quartering flight, and with the tail rotor rotating both top-forward and top-aft. The simulations indicate a significant level of unsteadiness in the performance of both main and tail rotors, especially in quartering flight, and a sensitivity to the direction of rotation of the tail rotor. Although the model thus captures behaviour that is similar to that observed in practice, the challenge still remains to integrate the information from high fidelity simulations such as these into routine calculations of the flight dynamics of helicopters.
18
Grachev, I. A., E. V. Kudashov, M. A. Bolotov, and N. D. Pronichev. "Model for evaluating the end runouts of a rotor with parallel connections of parts." VESTNIK of Samara University. Aerospace and Mechanical Engineering 20, no. 2 (2021): 83–96. http://dx.doi.org/10.18287/2541-7533-2021-20-2-83-96.
Full textAbstract:
The existing methods for calculating the assembly dimensional chains of aircraft engine rotors are analyzed. The factors that have a significant impact on the reliability of the calculation of the controlled assembly parameters of the product are identified. One of these factors is the existence of parallel connections of parts in the rotor. In the drum disk rotors, parallel rotor connections are formed by mating their parts along several end surfaces in the axial direction. A mathematical model is proposed that allows taking into account the parallel connections of the rotor parts. The form of relationship between rotor end run-outs and amplitudes of deviations of the shape of the mating surfaces of the parts and their angular positions in the unit is determined. The determined dependence includes many coefficients that allow taking into account the amplitudes of deviations of the shape of the mating surfaces, parallel connections of parts in the rotor, and their angular position. Determination of dependence coefficients values is solved as a problem of regression analysis. The initial data for obtaining the dependence are formed using the developed parameterized finite element model (FEM) of a part of the rotor of an aircraft engine high-pressure compressor (HPC). The results of research of end run-outs of control surfaces of disks of the considered HPC rotor assembly part are presented. The values of the dependence coefficients for assessing the end run-outs of the rotor are determined.
19
El-Shafei, A., A. S. El-Kabbany, and A. A. Younan. "Rotor Balancing Without Trial Weights." Journal of Engineering for Gas Turbines and Power 126, no. 3 (2004): 604–9. http://dx.doi.org/10.1115/1.1762903.
Full textAbstract:
The traditional balancing methods using trial or calibration weights are quite effective, yet too many trials may result in a lengthy balancing process. It had been suggested in the literature that it is possible to balance flexible rotors without the use of trial weights, if a rotor model is available. A procedure is developed in this paper to balance flexible rotors using complex modes and complex vibration measurements. It is shown that a complex rotor model is essential for the success of the technique. Moreover, careful calibration of the rotor model is the major cornerstone of the procedure. Experimental results illustrate the success of the procedure.
20
Scheaua, Fanel Dorel. "Comparative Numerical Analysis on Vertical Wind Turbine Rotor Pattern of Bach and Benesh Type." Energies 13, no. 9 (2020): 2311. http://dx.doi.org/10.3390/en13092311.
Full textAbstract:
In this work, 3D models in classic configuration of Bach and Benesh rotor type, as well as models with modified blade pattern geometry were analyzed from the air circulation point of view inside the rotor enclosure in order to identify the operating parameters differences according to rotor geometric modified configuration. Constructive design aspects are presented, as well as results obtained from the virtual model analysis in terms of circulation velocity and pressure values which enhance rotor operation related to torque and power coefficients. The rotors design pattern is made according to previous results obtained by different researchers who have performed numerical analysis on virtual models and tests on the experimental rotor models using the wind tunnel. The constructive solutions are describing two-bladed rotor models, in four new designed constructive variants and analyzed using ANSYS CFX. The air velocity specific values, static and total pressure recorded at the rotor blade level are highlighted, that influence the obtaining of rotor shaft torque and power. Also torque coefficient (CT) and power coefficient (CP) values according with specific values of tip speed ratio (TSR) are presented for each analyzed case. The analysis results show higher power coefficient values for analyzed Bach V2 and Benesh V2 rotor modified models compared to the classic Bach and Benesh models for 0.3 TSR of 0.11–012 CP, 0.4 TSR of 0.18 CP (Benesh V2 model) and 0.27 CP at 0.6 TSR (Bach V2). The resulted values confirm that Benesh V2 model offers higher CP up to 5% at TSR 0.3, 2% at TSR 0.6 and 3% at TSR 0.4 compared to the Benesh classical model. The Bach V2 model offers 4% higher CP compared to the classic Bach model at TSR 0.6. Based on these results it is intended the further analytical and experimental research in order to obtain optimal rotor pattern.
21
Yang, S.-C. "A mathematical model of a cc-type single-screw compressor." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 218, no. 4 (2004): 437–48. http://dx.doi.org/10.1177/095440620421800408.
Full textAbstract:
In this paper, a method is proposed for determining a basic profile of a cc-type single-screw compressor including the gate rotor and the screw rotor. The cc-type has a cylindrical screw and two cylindrical gate rotors. Based on this method, a mathematical model of the meshing principles of a cc-type screw rotor meshed with a gate rotor, that has either straight edge teeth or conical teeth, is presented. The inverse envelope concept is used to determine the cutting-edge curve of a gate rotor. Based on this concept, the required cutter for machining a cc-type screw rotor can be obtained by the envelope of a one-parameter family. The obtained screw rotor is an envelope to the family of the gate rotor's surfaces. The obtained envelope becomes the generating surface. The inverse envelope can be used to obtain the envelope to the family of generating surfaces. Then the profile of a gate rotor cutting-edge curve can be easily obtained. The surface analysis including contact lines is shown for the design and manufacture of a screw compressor. As an example, the cc-type single-screw compressor with a compressor ratio of 11:6 was determined with the aid of the proposed mathematical model. Using rapid prototyping (RP) and manufacturing technology, a cc-type single-screw rotor with a gate rotor was designed. The RP primitives provide an actual full-size physical model that can be analysed and used for further development. Results from these mathematical models should have applications in the design of cc-type single-screw compressors.
22
Huang, Yao-Tien, Ying-Chieh Liu, Kun-Nan Chen, and Yueh-Mei Lai. "Structural Optimization of Vented Brake Rotors with a Fully Parameterized Model." Applied Sciences 12, no. 4 (2022): 2184. http://dx.doi.org/10.3390/app12042184.
Full textAbstract:
Vented brake rotors used in an automobile behave similarly to centrifugal fans, drawing cool air from the inboard side, passing it through the disc vents, and exhausting it from the periphery. A vented brake rotor with a better heat dispersing ability is often superior to a solid rotor, in both thermal performance and brake efficiency. In this research, a fully parameterized model for a ventilated brake rotor is created using the ANSYS Parametric Design Language, to uniquely define the rotor’s geometry. With this parameterized model, two structural optimization cases are studied in this paper. The first one investigated is a modal frequency separation problem: The frequency differences in a tangential mode sandwiched between two nodal diameter modes of the brake rotor model are maximized. An automatic identification scheme for extracting correct mode orders is implemented in the program to track the correct modes during optimization. The second case is a thermal deformation problem: The distortion on the frictional surfaces of the rotor loaded with heat flux generated during the braking process is minimized. The optimization results show that a brake rotor design with a thinner outboard disc and a thicker inboard disc provides a great choice for rotor coning reduction.
23
Ilie, K., and A. Subic. "Parametric modelling of helical rotors for efficient design of twin-screw superchargers." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 221, no. 2 (2007): 267–72. http://dx.doi.org/10.1243/0954406jmes421ft.
Full textAbstract:
The parametric three-dimensional geometric model of twin-screw supercharger rotors of any aspect ratio was developed. For model validation through visualization, computer-aided design (CAD) rotor models with scalable data were generated in commercial CAD software and calibrated experimentally by laser Doppler velocimetry (LDV) tests. Calibrated rotor profile data can be transferred into CAD-CFD interface for flow simulation for performance optimization.
24
Zhong, Shun, Suxia Zhang, Jie Yang, and Yanan Zhang. "Correlation Analysis and Its Application on an Asymmetry Rotor Structure with Overhang." Applied Sciences 11, no. 23 (2021): 11501. http://dx.doi.org/10.3390/app112311501.
Full textAbstract:
Overhung rotors are widely used in the industrial field. However, compared with normal structure rotors, the prediction and control of overhung rotors cannot achieve good performance. The work aims to investigate the dynamical behaviours of an overhung rotor by means of correlation analysis, and find its possible application. In this work, based on a real type of rotor, the dynamic model of the rotor with overhang is established by means of the finite element method. Simulation of the dynamic model with different input positions and support stiffnesses is conducted. Based on the methodology of correlation analysis, by introducing a correlation parameter of a proportion of amplitude of measured signal and imbalance mass, the position which has most effect on the vibration is found. Meanwhile, an experiment on the same type of overhung rotor is carried out to validate the results. The numerical results and corresponding experimental results prove that the overhung node has the most effect on the vibration amplitudes of the measured points. Choosing the overhung node to add trial weight, the overhung rotor can be easily balanced. The theory provides an alternative approach to modal analysis which needs more knowledge of the system.
25
Varatharajoo, Renuganth, Faizal Mustapha, Dayang Laila Abang Abdul Majid, Rizal Zahari, and Ralph Kahle. "Critical Speeds for Carbon/Epoxy Composite Rotors in Spacecraft Energy Storage Applications." Key Engineering Materials 471-472 (February 2011): 37–42. http://dx.doi.org/10.4028/www.scientific.net/kem.471-472.37.
Full textAbstract:
A numerical investigation to optimize the carbon/epoxy multi layer composite rotor is performed for the spacecraft energy storage application. A high-speed double and triple layer rotor design is proposed and different composite materials are tested to achieve the most suitable recipe. First, analytical rotor evaluation was performed in order to establish a reliable numerical composite rotor model. Subsequently, finite element analysis is employed in order to optimize the double and triple layer composite rotors. Then, the modal analysis was carried out to determine the rotor natural frequencies. The rotor stress distributions and the rotor mode shapes show that a safe operational regime below 46, 000 rotations per minute is achievable.
26
Spagnol, Joseph, Helen Wu, and Chunhui Yang. "Application of Non-Symmetric Bending Principles on Modelling Fatigue Crack Behaviour and Vibration of a Cracked Rotor." Applied Sciences 10, no. 2 (2020): 717. http://dx.doi.org/10.3390/app10020717.
Full textAbstract:
Many studies on cracked rotors developed crack breathing models that assume that the neutral axis of bending always remains horizontal for simplification. These models may generate significant discrepancies and thus there is a need to develop more sophisticated models to look into the shifting of the neutral axis for a cracked rotor. Herein, a case study on the shifting of the neutral axis for a cracked rotor is firstly performed by using a three-dimensional finite element model to confirm that the neutral axis becomes inclined as the cracked rotor rotates. In response to this finding, non-symmetric bending principles are used to develop a new crack breathing model which has the advantage of being able to numerically calculate the inclination angle of the neutral axis. When compared to an existing crack model in the literature that assumes that the neutral axis remains horizontal (HNA model), the proposed model is relatively less stiff in bending as a result of an overall lower area moment of inertia. Using the harmonic balance method, a two-dimensional finite element vibration model of a cracked rotor was devised by employing the proposed crack breathing model and the HNA model for validation. It can be found that the vibration amplitudes of the first three frequency components are similar between the two models for shallow cracks and significantly differed for deep cracks. This result highlights the potential of the proposed model for modelling and detecting mid-to-late-stage cracks in rotors.
27
Hayami, H., Y. Senoo, Y. I. Hyun, and M. Yamaguchi. "Effects of Tip Clearance of Nozzle Vanes on Performance of Radial Turbine Rotor." Journal of Turbomachinery 112, no. 1 (1990): 58–63. http://dx.doi.org/10.1115/1.2927421.
Full textAbstract:
In radial turbines with variable nozzles, the flow downstream of the nozzles could be distorted by the leakage flow through the tip clearance of the upstream nozzle vanes. To investigate the effects of flow distortion on the performance of turbine rotors, two rotors with different numbers of blades were tested for three types of distorted velocity distribution at the rotor inlet. In the case of the 20-blade rotor with moderate blade loading, the flow distortion at the rotor inlet had a negligible effect on the rotor characteristics, and the measured data on the turbine performances agreed well with prediction. Predictions were made with a conventional one-dimensional flow model applied to the rotor flow, while a two-layer flow model was applied to the flow in the nozzle with clearance. In the case of the 10-blade rotor with heavy blade loading, however, the rotor performance was found to be sensitive to the inlet flow distortion and was considerably lower than the prediction.
28
Pacholczyk, Michał, and Dariusz Karkosiński. "Parametric Study on a Performance of a Small Counter-Rotating Wind Turbine." Energies 13, no. 15 (2020): 3880. http://dx.doi.org/10.3390/en13153880.
Full textAbstract:
A small Counter-Rotating Wind Turbine (CRWT) has been proposed and its performance has been investigated numerically. Results of a parametric study have been presented in this paper. As parameters, the axial distance between rotors and a tip speed ratio of each rotor have been selected. Performance parameters have been compared with reference to a Single Rotor Wind Turbine (SRWT). Simulations were carried out with Computational Fluids Dynamics (CFD) solver and a Large Eddy Scale approach to model turbulences. An Actuator Line Model has been chosen to represent rotors in the computational domain. Summing up the results of simulation tests, it can be stated that when constructing a CRWT turbine, rotors should be placed at a distance of at least 0.5 D (where D is rotor outer diameter) or more. One can then expect a noticeable power increase compared to a single rotor turbine. Placing the second rotor closer than 0.5 D guarantees a significant increase in power, but in such configurations, dynamic interactions between the rotors are visible, resulting in fluctuations in torque and power. Dynamic interactions between rotor blades above 0.5 D are invisible.
29
Lee, Yu-Been, and Jae-Sang Park. "Hover Performance Analyses of Coaxial Co-Rotating Rotors for eVTOL Aircraft." Aerospace 9, no. 3 (2022): 152. http://dx.doi.org/10.3390/aerospace9030152.
Full textAbstract:
Hover performance analyses of coaxial co-rotating rotors (or stacked rotors), which can be used as lifting rotors for electric VTOL (eVTOL) aircraft, are conducted here. In this study, the rotorcraft comprehensive analysis code, CAMRAD II, is used with the general free-wake model. The generic coaxial co-rotating rotor without the blade taper and built-in twist is considered as the baseline rotor model, and the rotor is trimmed to match a prescribed rotor thrust value. The hover performance, including the rotor power and Figure of Merit (FM), is investigated for various index angles, axial spacings, blade taper ratios, and built-in twist angles. A maximum FM value is obtained near an index angle of 0° and 10° when the axial spacing is below and above 5.27%R, respectively. When the index angle is 0° and axial spacing is 1.44% R, the maximum increments in the FM are 3.03% and 6.06%, respectively, for a rotor with a blade taper ratio of 0.8 and a built-in twist angle of −12°. Therefore, this simulation study demonstrates that the hover performance of coaxial co-rotating rotors can be changed by adjusting the index angle or the axial spacing.
30
Tan, J., Y. Sun, and G. N. Barakos. "Unsteady loads for coaxial rotors in forward flight computed using a vortex particle method." Aeronautical Journal 122, no. 1251 (2018): 693–714. http://dx.doi.org/10.1017/aer.2018.8.
Full textAbstract:
ABSTRACTRecent advances in coaxial rotor design have shown benefits of this configuration. Nevertheless, issues related to rotor-head drag, aerodynamic performance, wake interference, and vibration should also be considered. Simulating the unsteady aerodynamic loads for a coaxial rotor, including the aerodynamic interactions between rotors and rotor blades, is an essential part of analysing their vibration characteristics. In this article, an unsteady aerodynamic analysis based on a vortex particle method is presented. In this method, a reversed-flow model for the retreating side of the coaxial rotor is proposed based on an unsteady panel technique. To account for reversed flow, shedding a vortex from the leading edge is used rather than from the trailing edge. Moreover, vortex-blade aerodynamic interactions are accounted for. The model considers the unsteady pressure term induced on a blade by tip vortices of other blades, and thus accounts for the aerodynamic interaction between the rotors and its contribution to the unsteady airloads. Coupling the reversed-flow model and the vortex-blade aerodynamic interaction model with the viscous vortex-particle method is used to simulate the complex wake of the coaxial rotor. The unsteady aerodynamic loads on the X2 coaxial rotor are simulated in forward flight, and compared with the results of PRASADUM (Parallelized Rotorcraft Analysis for Simulation And Design, developed at the University of Maryland) and CFD/CSD computations with the OVERFLOW and the CREATE-AV Helios tools. The results of the present method agree with the results of the CFD/CSD method, and compare to it better than the PRASADUM solutions. Furthermore, the influence of the aerodynamic interaction between the coaxial rotors on the unsteady airloads, frequency, wake structure, induced flow, and force distributions are analysed. Additionally, the results are also compared against computations for a single-rotor case, simulated at similar conditions as the coaxial rotor. It is shown that the effect of tip vortex interaction plays a significant role in unsteady airloads of coaxial rotors at low speeds, while the rotor blade passing effect is obviously strengthened at high-speed.
31
Chen, Yue, Jiwen Cui, and Xun Sun. "An Unbalance Optimization Method for a Multi-Stage Rotor Based on an Assembly Error Propagation Model." Applied Sciences 11, no. 2 (2021): 887. http://dx.doi.org/10.3390/app11020887.
Full textAbstract:
For the assembly of a multi-stage rotor, such as an aero-engine or gas turbine, the parts need to be assembled optimally to avoid excessive unbalance. We propose a method to optimize the unbalance of a multi-stage rotor during assembly. First, we developed an assembly error propagation model for a multi-stage rotor. The alignment process and distribution of the screw holes of the adjacent rotors was considered for the first time. Secondly, we propose a new assembly datum for unbalance optimization to ensure consistency with the actual conditions of a dynamic balance test. Finally, the unbalance optimization of a multi-stage rotor was achieved using a genetic algorithm, and the corresponding optimal assembly orientations of rotors at different stages were also identified. The results of the simulations showed that the assembly error propagation model had high accuracy and that the genetic optimization process had good convergence. The effect of unbalance optimization was also proven with experiments.
32
Chan, W., and J. Perry. "Use of aerofoil section dynamic stall synthesis methods in rotor design." Aeronautical Journal 116, no. 1179 (2012): 501–20. http://dx.doi.org/10.1017/s0001924000007004.
Full textAbstract:
Abstract The introduction of the original time delay method of Beddoes, an engineering model for the unsteady response of an aerofoil section including dynamic stall, had a profound effect on the design and development of rotor systems in the UK. Over the years, the model expanded to include more and more features of the unsteady flow, with many contributors. It is now in use throughout the world as part of rotor analysis packages. Nevertheless, it retains its essential simplicity. Work to confirm the ability of the most recent version of the dynamic stall model from the University of Glasgow to replicate the complicated behaviour of an advanced rotor aerofoil section at full scale Reynolds and Mach numbers provides an opportunity to review the use of this new engineering model in the helicopter rotor design environment. This note discusses the application of dynamic stall synthesis methods to the problem of classifying and comparing aerofoil sections when designing rotors for the retreating blade stall condition that determines the rotor blade area requirement of the helicopter. The development of the dynamic stall models employed in UK rotor designs is reviewed in this paper and their use in the design process explained, with emphasis on the assumptions that overcome the limitations of the models and exploit their simplicity, enabling accurate and conservative rotor designs. The paper shows how the model may be used to structure the analysis of complex sets of dynamic aerofoil data. It illustrates how structured comparison between the model and the data yields a concise appreciation of the behaviour of the aerofoil and an understanding of the physical processes involved. Some previously unappreciated effects are identified and the model is used to transfer experience of the aerofoil section behaviour from the non-rotating wind-tunnel environment to that of the rotor. Finally, the application of the new engineering model developed at Glasgow University in the rotor design process is outlined. Some remarks on the use of engineering models in comparison with CFD models in the design context are included.
33
Hathout, J. P., A. El-Shafei, and R. Youssef. "Active Control of Multi-Mode Rotor-Bearing Systems Using HSFDs." Journal of Tribology 119, no. 1 (1997): 49–56. http://dx.doi.org/10.1115/1.2832479.
Full textAbstract:
This paper summarizes the modeling and control of hybrid squeeze film dampers (HSFDs) for active control of vibration of rotors exhibiting multiple modes. In a recent paper (El-Shafei and Hathout, 1994), it was shown that the automatically controlled HSFD based on feedback on rotor speed can be a very efficient device for active control of rotor vibration. It was shown that this closed-loop, on-off control strategy results in a much improved behavior of the rotor system. The previous investigation was performed on a Jeffcott rotor model. The model was simple and fluid inertia effects were not taken into consideration. In this paper, major strides were made in both the modeling of the rotor and the HSFD. Modal analysis was implemented in the dynamic analysis of the squeeze film damper supported rotor in a novel and unique manner of performing modal analysis on nonlinear rotor systems. This allowed the modeling of any number of modes using modal analysis and hence to verify the capability of the HSFD to control multiple modes. Also, fluid inertia forces were considered in our model for the HSFD due to their direct influence in changing the behavior of the damper (El-Shafei and Crandall, 1991). A complete mathematical model of this open-loop system is developed and is implemented on a digital computer. Finally, based on the feedback on speed, the closed-loop behavior was studied from both steady-state and transient points of view and showed an overall enhanced behavior for the rotor system.
34
Ye, Ting, Zhengdong Wang, and Fu-Zhen Xuan. "Modeling the creep damage effect on the creep crack growth behavior of rotor steel." Open Physics 16, no. 1 (2018): 517–24. http://dx.doi.org/10.1515/phys-2018-0068.
Full textAbstract:
AbstractTo evaluate the fracture life of steam turbine HP-IP rotors more accurately, an understanding of the creep damage effect on creep cracking performance of service-exposed rotor steel, and a proper creep crack growth (CCG) model considering the creep damage effect, is essential. In the present work comparative CCG tests were carried out on virgin and rotor steel that had been in service for 16 years, to examine the differences in creep crack microstructure and CCG rate between these two specimen types. Test results showed that the CCG rate of service-exposed steel is accelerated by creep damage due to metallurgical deterioration. Based on the CCG model derived by Webster, an improved CCG model is proposed by replacing the constant exponent with a creep-damage-related variable. To validate the improved model, a comparison of da/dt vs. C* between experiment data and the CCG models was conducted. The predictive result of the improved model is in better agreement with the experiment results than the classical CCG and Webster models for the service-exposed rotor steel. With decrement of C* value within the improved CCG model, the remaining life of HP-IP rotors may be predicted more accurately.
35
Su, Jianmin, Chengyue Su, Sheng Xu, and Xiaoxing Yang. "A Multibody Model of Tilt-Rotor Aircraft Based on Kane’s Method." International Journal of Aerospace Engineering 2019 (April 16, 2019): 1–10. http://dx.doi.org/10.1155/2019/9396352.
Full textAbstract:
A tilt-rotor aircraft can switch between two flight configurations (the helicopter configuration and the fixed-wing plane configuration) by tilting its rotors. In the process of rotor tilting, the nacelles which drive the rotors tilt together with the rotors. Because the mass of the nacelles cannot be ignored compared to the mass of the whole aircraft, the tilting of the nacelles is a coupling motion of the body and the nacelles. In order to better character the aircraft dynamics during the nacelle tilting, a multibody model is established in this paper. In this multibody model, Kane’s method is used to build a dynamic model of a tilt-rotor aircraft. The generalized rates are used to describe the movement of the body and the nacelles (with rotors). The generalized active forces and generalized inertial forces of both the body and the nacelles (with rotors) are obtained, respectively, and the first-order differential equations of the generalized rates are obtained. The longitudinal trim of the XV-15 aircraft is calculated according to the single-body model and our multibody model, in this paper, and the results verify the correctness of the multibody model. In the process of nacelle inclination angle command tracking, the multibody model can provide more information about the disturbance torque of the nacelle than the single-body model, and model inversion control based on the proposed multibody model can obtain a better tracking result than a PID control method only using nacelle angle feedback information.
36
Zhang, Yiming, Jiqiang Tang, and Tong Wen. "A Modified Transfer Matrix Method for Modal Analysis of Stepped Rotor Assembly Applied in the Turbomolecular Pump." Shock and Vibration 2022 (February 27, 2022): 1–13. http://dx.doi.org/10.1155/2022/3692081.
Full textAbstract:
An accurate modal analysis of the stepped rotor assembly is significant in the design process of rotors. The transfer matrix method (TMM) is widely used in the modal analysis of the rotor. However, the influences of the step and the assembling modes are not considered in the traditional TMM. In this paper, a modified transfer matrix method is presented for the modal calculation of the rotor in the turbomolecular pump. The stiffness reduction of stepped segments and the effect of assembled components are considered in this modified method. First of all, the traditional transfer matrix model is built. Then, the stepped segments of the rotor are changed into conical segments and the lumped mass model of conical segments is calculated. Next, the conicities of conical segments are analyzed and relations between conicities and dimensions of the rotor are discovered. Finally, the stiffness factors which can describe the effects of different assembling modes are introduced and optimized. The optimized stiffness factors are analyzed and explained from the perspective of contact stress. The modal of the stepped rotor assembly could be computed with high accuracy by using this method.
37
Zheng, Nan, Mo-li Chen, Gui-Huo Luo, and Zhi-Feng Ye. "Dynamic Behavior Analysis of Intermediate Bearing-Squeeze Film Dampers-Rotor System under Constant Maneuvering Overload." Shock and Vibration 2021 (April 30, 2021): 1–24. http://dx.doi.org/10.1155/2021/5512409.
Full textAbstract:
Under the flight maneuvering of an aircraft, the maneuvering load on the rotor is generated, which may induce the change of dynamic behavior of aeroengine rotor system. To study the influence on the rotor dynamic behavior of constant maneuvering overload, a nonlinear dynamic model of bearing-rotor system under arbitrary maneuver flight conditions is presented by finite element method. The numerical integral method is used to investigate the dynamic characteristics of the rotor model under constant maneuvering overload, and the simulation results are verified by experimental works. Based on this, the dynamic characteristics of a complex intermediate bearing-squeeze film dampers- (SFD-) rotor system during maneuvering flight are analyzed. The simulation results indicate that the subharmonic components are amplified under constant maneuvering overload. The amplitude of the combined frequency components induced by the coupling of the inner and outer rotors is weakened. The static displacements of the rotor caused by the additional excitation force are observed. Besides, the period stability of the movement of the rotor deteriorates during maneuver flight. The design of counterrotation of the inner and outer rotors can effectively reduce the amplitude of subharmonic under constant maneuvering overload.
38
Panayotov, Filip, Ivan Dobrev, Fawaz Massouh, and Michael Todorov. "Experimental study of a helicopter rotor model in hover." MATEC Web of Conferences 234 (2018): 01002. http://dx.doi.org/10.1051/matecconf/201823401002.
Full textAbstract:
This paper presents the results from an experimental study of the aerodynamic performance and efficiency of a model helicopter rotor in steady hover at Reynolds numbers below 70000. Results are shown for a two-, three- and four-bladed rotor configuration for various pitch angles and speeds of rotation. The influence of the rotor solidity on the aerodynamic efficiency in terms of the Figure of Merit is highlighted. The profile drag component is evaluated as a function of the Reynolds number. The internal friction losses of the test stand are estimated and taken into account in all measurements. A brief description of the designed test stand is provided. The experimental setup allows for the measurement of thrust and torque of helicopter rotors with diameters of up to 1 meter, for pitch angles varying from -12° to +24° and for rotational speeds of up to 3000 RPM. Conclusions are drawn about the aerodynamic performance and efficiency of the studied rotor configurations. This experimental study provided a significant database, which will serve for validation purposes.
39
Dai, Yuting, Linpeng Wang, Chao Yang, and Xintan Zhang. "Dynamic Gust Load Analysis for Rotors." Shock and Vibration 2016 (2016): 1–12. http://dx.doi.org/10.1155/2016/5727028.
Full textAbstract:
Dynamic load of helicopter rotors due to gust directly affects the structural stress and flight performance for helicopters. Based on a large deflection beam theory, an aeroelastic model for isolated helicopter rotors in the time domain is constructed. The dynamic response and structural load for a rotor under the impulse gust and slope-shape gust are calculated, respectively. First, a nonlinear Euler beam model with 36 degrees-of-freedoms per element is applied to depict the structural dynamics for an isolated rotor. The generalized dynamic wake model and Leishman-Beddoes dynamic stall model are applied to calculate the nonlinear unsteady aerodynamic forces on rotors. Then, we transformed the differential aeroelastic governing equation to an algebraic one. Hence, the widely used Newton-Raphson iteration algorithm is employed to simulate the dynamic gust load. An isolated helicopter rotor with four blades is studied to validate the structural model and the aeroelastic model. The modal frequencies based on the Euler beam model agree well with published ones by CAMRAD. The flap deflection due to impulse gust with the speed of 2m/s increases twice to the one without gust. In this numerical example, results indicate that the bending moment at the blade root is alleviated due to elastic effect.
40
Jiang, Minghong, Zhaoli Zheng, Yonghui Xie, and Di Zhang. "Local Sensitivity Analysis of Steady-State Response of Rotors with Rub-Impact to Parameters of Rubbing Interfaces." Applied Sciences 11, no. 3 (2021): 1307. http://dx.doi.org/10.3390/app11031307.
Full textAbstract:
Local sensitivity analysis, which describes the relative importance of specific design parameters to the response of systems, is crucial for investigating dominant factors in optimal design. In this paper, local sensitivity analysis of the response of rotors with rub-impact to parameters of rubbing interfaces is carried out. The steady-state motion of the rotor is evaluated by a harmonic balance method and the sensitivity coefficients for every rotation speed over the speed range are derived analytically. Two classical models, including the Duffing oscillator and the gap model, are utilized to validate the accuracy and capability of the adopted methods and high accuracy is shown. Numerical investigations of sensitivities of steady-state response of rotors to parameters of rubbing interfaces are then carried out, based on a lumped Jeffcott rotor and a finite element model respectively. Conclusions are drawn that the response of rotors subjected to rubbing problems is more sensitive to initial clearance than other parameters of the applied friction model. With increase of initial gap, the response of rotors becomes more sensitive and the range of region subjected to rub-impact forces shrinks until the separation of rotor and stator.
41
Ghaisas, Niranjan S., Aditya S. Ghate, and Sanjiva K. Lele. "Effect of tip spacing, thrust coefficient and turbine spacing in multi-rotor wind turbines and farms." Wind Energy Science 5, no. 1 (2020): 51–72. http://dx.doi.org/10.5194/wes-5-51-2020.
Full textAbstract:
Abstract. Large eddy simulations (LESs) are performed to study the wakes of a multi-rotor wind turbine configuration comprising four identical rotors mounted on a single tower. The multi-rotor turbine wakes are compared to the wake of a conventional turbine comprising a single rotor per tower with the same frontal area, hub height and thrust coefficient. The multi-rotor turbine wakes are found to recover faster, while the turbulence intensity in the wake is smaller, compared to the wake of the conventional turbine. The differences with the wake of a conventional turbine increase as the spacing between the tips of the rotors in the multi-rotor configuration increases. The differences are also sensitive to the thrust coefficients used for all rotors, with more pronounced differences for larger thrust coefficients. The interaction between multiple multi-rotor turbines is contrasted with that between multiple single-rotor turbines by considering wind farms with five turbine units aligned perfectly with each other and with the wind direction. Similar to the isolated turbine results, multi-rotor wind farms show smaller wake losses and smaller turbulence intensity compared to wind farms comprised of conventional single-rotor turbines. The benefits of multi-rotor wind farms over single-rotor wind farms increase with increasing tip spacing, irrespective of the axial spacing and thrust coefficient. The mean velocity profiles and relative powers of turbines obtained from the LES results are predicted reasonably accurately by an analytical model assuming Gaussian radial profiles of the velocity deficits and a hybrid linear-quadratic model for the merging of wakes. These results show that a larger power density can be achieved without significantly increased fatigue loads by using multi-rotor turbines instead of conventional, single-rotor turbines.
42
Chen, Yue, Jiwen Cui, and Xun Sun. "A Vibration Suppression Method for the Multistage Rotor of an Aero-Engine Based on Assembly Optimization." Machines 9, no. 9 (2021): 189. http://dx.doi.org/10.3390/machines9090189.
Full textAbstract:
The assembly quality of the multistage rotor is an essential factor affecting its vibration level. The existing optimization methods for the assembly angles of the rotors at each stage can ensure the concentricity and unbalance meet the requirements, but it cannot directly ensure its vibration responses meet the indexes. Therefore, in this study, we first derived the excitation formulas of the geometric and mass eccentricities on the multistage rotor and introduced it into the dynamics model of the multistage rotor system. Then, the coordinate transfer model of the geometric and mass eccentricities errors, including assembly angles of the rotors at all stages, was established. Moreover, the mathematical relationship between the assembly angles of the rotors at all stages and the nodal vibration responses was established by combining the error transfer model with the dynamics model of the multistage rotor system. Furthermore, an optimization function was developed, which takes the assembly angles as the optimization variables and the maximum vibration velocity at the bearings as the optimization objective. Finally, a simplified four-stage high-pressure rotor system was assembled according to the optimal assembly angles calculated in the simulations. The experimental results showed that the maximum vibration velocity at the bearings under the optimal assembly was reduced by 69.6% and 45.5% compared with that under the worst assembly and default assembly. The assembly optimization method proposed in this study has a significant effect on the vibration suppression of the multistage rotor of an aero-engine.
43
Wang, Jun Yu, Dong Mei Ji, Xiu Ping Yao, Jin Yuan Shi, and Yu Yang. "Research on Stress Field of the Steam Turbine Rotor Based on SVM and the Finite Element Analysis." Advanced Materials Research 354-355 (October 2011): 446–53. http://dx.doi.org/10.4028/www.scientific.net/amr.354-355.446.
Full textAbstract:
A model for on-line calculation of equivalent stresses in steam turbine rotors has been built up based on Support Vector Machine (SVM) neural network and the finite element method. Regarding 125MW steam turbine rotor as an object, SVM method is employed as a tool to train large numbers of date about the equivalent stress of the rotor, which obtained from the finite element method. A model can be gotten after finishing training the data. Equivalent stresses of rotor obtained with finite element and SVM model are compared during cold start. Results show that similar calculation results of equivalent stress may be obtained with either finite element or SVM model. However, with the latter one, the calculation becomes easier and fast, which is applicable for on-line calculation of equivalent stresses in turbine rotors, and may serve as a reference for on-line life management of turbine rotors.
44
Mimmi, G., and P. Pennacchi. "Analytical model of a particular type of positive displacement blower." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 213, no. 5 (1999): 517–26. http://dx.doi.org/10.1243/0954406991522743.
Full textAbstract:
Many papers exist in the literature that deal with the twin-screw compressor. This usually has two different rotors, a male and a female, and is commonly used to produce compressed gas for industrial uses. However, a different type of positive displacement rotary compressor with two screws is sometimes used, one of its typical applications being in car engine supercharging. The present paper deals with the latter type, which is defined as a two-screw blower. This blower has two identical helical rotors, each with three lobes. The kinematics and the geometry of the rotors are analysed here, and a complete mathematical model for the rotor is defined. Moreover, different possible shapes of the rotors, depending on the design parameters, are analysed and the limitations in the choice of the design parameters are presented. Finally, an analysis of the theoretical specific slipping of the rotors is presented, showing which zones of the profile are the most stressed. This model will be useful for further studies on rotor pressure loads and blower dynamics.
45
Park, J. S., and S. N. Jung. "Comprehensive multibody dynamics analysis for rotor aeromechanics predictions in descending flight." Aeronautical Journal 116, no. 1177 (2012): 229–49. http://dx.doi.org/10.1017/s0001924000006813.
Full textAbstract:
AbstractThis paper studies the rotor aeromechanics in descending flight using a nonlinear flexible multibody dynamic analysis code, DYMORE. A freewake model is included in DYMORE to improve the rotor wake modelling. The wind-tunnel test data of the Higher-harmonic Aeroacoustics Rotor Test (HART) II rotor, with and without higher harmonic pitch control (HHC), and the flight test data of the full-scale utility helicopter rotor in descent are used for the aeromechanics correlation at an advance ratio of 0·15. The blade-vortex interaction (BVI) airloads are reasonably predicted for both the HART II and utility helicopter rotors, although some BVI peaks are missed on the advancing sides for both the rotors. The flap deflections and elastic torsion deformations at the blade tip are fairly correlated against the measured data of the HART II rotor. The correlation of blade structural moments for both HART II and utility helicopter rotors are not as good as the lift predictions; however, a reasonable prediction is obtained for the utility helicopter rotor.
46
Wang, Danyang, Chunrong Hua, Dawei Dong, Biao He, and Zhiwen Lu. "Crack Parameters Identification Based on a Kriging Surrogate Model for Operating Rotors." Shock and Vibration 2018 (October 8, 2018): 1–12. http://dx.doi.org/10.1155/2018/9274526.
Full textAbstract:
Parameters identification of cracked rotors has been gaining importance in recent years, but it is still a great challenge to determine the crack parameters including crack location, depth, and angle for operating rotors. This work proposes a new method to identify crack parameters in a rotor-bearing system based on a Kriging surrogate model and an improved nondominated sorting genetic algorithm-III (NSGA-III). A rotor-bearing system with a breathing crack is established by the finite element method and the superharmonic components are used as index to detect the cracks, the Kriging surrogate model between crack parameters and the superharmonic component amplitudes of the vibration response for rotors are constructed, and an improved NSGA-III is proposed to obtain the optimal crack parameters. Numerical experiments show that the proposed method can identify the crack location, depth, and angle accurately and efficiently for operating rotors.
47
Srinivasarao, Gopisetti, Arun K. Samantaray, and Sanjoy K. Ghoshal. "Bond graph modeling and multi-body dynamics of a twin rotor system." Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 235, no. 1 (2020): 117–44. http://dx.doi.org/10.1177/0959651819899267.
Full textAbstract:
The dynamics of a twin-rotor multi-input multi-output system, which is similar to that of a helicopter in many ways, is highly nonlinear in nature. In this article, a detailed dynamical model of twin-rotor multi-input multi-output system is developed and simulated by using bond graph approach. Nonlinear nature of the interface gain, thrust, and drag forces, and the stiffness of cable attached to support column joint are estimated. The rotors are modeled through the Newton–Euler equations. The bond graph model is created by using the generic sub-models and the same set of sub-models can be assembled differently to model many other similar systems such as tricopters and quadcopters. Inertial forces and moments, rotor thrust and drag forces, active and reactive motor torques, and direct current motor dynamics are considered in the model. The responses from the model are compared with the test data for validation.
48
Knotek, Jiří, Pavel Novotný, Ondřej Maršálek, Peter Raffai, and Jozef Dlugoš. "The Influence of Rotor Unbalance on Turbocharger Rotor Dynamics." Journal of Middle European Construction and Design of Cars 13, no. 3 (2015): 8–13. http://dx.doi.org/10.1515/mecdc-2015-0010.
Full textAbstract:
Shrnutí Članek analyzuje vliv nevyvahy na dynamiku rotoru turbodmychadla. Je zde prezentovan 3D vypočtovy model rotoru turbodmychadla a hydrodynamicky model kluzne ložiska. Sestaveni vysledneho vypočtoveho modelu na urovni virtualniho prototypu je provedeno v prostředi software pro řešeni dynamiky těles. Članek prezentuje vybrane vysledky, na kterych je podrobně rozebran vliv velikosti nevyvahy na dynamiku rotoru turbodmychadla.
49
Wang, Aiming, Yujie Bi, Yun Xia, Xiaohan Cheng, Jie Yang, and Guoying Meng. "Continuous Rotor Dynamics of Multi-Disc and Multi-Span Rotor: A Theoretical and Numerical Investigation on the Continuous Model and Analytical Solution for Unbalance Responses." Applied Sciences 12, no. 9 (2022): 4351. http://dx.doi.org/10.3390/app12094351.
Full textAbstract:
Continuous rotor dynamics remains stagnant. In this paper, aim at multi-span and multi-disc rotor-bearing system, the continuous rotor dynamic analysis method (CRDAM) is proposed. The force acting on the shaft by the rotating eccentric disc is simulated as a point force. The counterforce of bearing is also considered as a point force. The shaft is considered free-ended. A continuous rotor dynamic model is obtained and an analytical solution is proposed to express the unbalance response as function of the position, unbalance, support stiffness and damping. The proposed method is validated by numerical experiments in which unbalance responses obtained by it are compared with that obtained by the two classical methods the finite element method (FEM) and Ricatti method. The results indicate that the proposed method is applicable to calculating unbalance response of multi-disc and multi-span rotor. Moreover, it is closer to FEM than Ricatti and can be applied to actual high speed rotors. Among the three methods, the calculating speed of Ricatti is the fastest, CRDAM is the second fastest and FEM is the slowest. The proposed method, which solves the forward problems of the continuous rotor dynamics for the multi-disc and multi-span rotors, can provide theoretical basis for further studies on inverse problems such as identification of rotor unbalance and bearing stiffness and damping coefficients without test runs and external excitations.
50
Wang, Aiming, Yujie Bi, Yun Xia, Xiaohan Cheng, Jie Yang, and Guoying Meng. "Continuous Rotor Dynamics of Multi-Disc and Multi-Span Rotor: A Theoretical and Numerical Investigation on the Continuous Model and Analytical Solution for Unbalance Responses." Applied Sciences 12, no. 9 (2022): 4351. http://dx.doi.org/10.3390/app12094351.
Full textAbstract:
Continuous rotor dynamics remains stagnant. In this paper, aim at multi-span and multi-disc rotor-bearing system, the continuous rotor dynamic analysis method (CRDAM) is proposed. The force acting on the shaft by the rotating eccentric disc is simulated as a point force. The counterforce of bearing is also considered as a point force. The shaft is considered free-ended. A continuous rotor dynamic model is obtained and an analytical solution is proposed to express the unbalance response as function of the position, unbalance, support stiffness and damping. The proposed method is validated by numerical experiments in which unbalance responses obtained by it are compared with that obtained by the two classical methods the finite element method (FEM) and Ricatti method. The results indicate that the proposed method is applicable to calculating unbalance response of multi-disc and multi-span rotor. Moreover, it is closer to FEM than Ricatti and can be applied to actual high speed rotors. Among the three methods, the calculating speed of Ricatti is the fastest, CRDAM is the second fastest and FEM is the slowest. The proposed method, which solves the forward problems of the continuous rotor dynamics for the multi-disc and multi-span rotors, can provide theoretical basis for further studies on inverse problems such as identification of rotor unbalance and bearing stiffness and damping coefficients without test runs and external excitations.