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Soo-Yong Cho Eui-Soo Yoon Bum-Seog Choi 《Journal of Mechanical Science and Technology》2002,16(8):1154-1164
Losses on the turbine consist of the mechanical loss, tip clearance loss, secondary flow loss and blade profile loss etc.,.
More than 60 % of total losses on the turbine is generated by the two latter loss mechanisms. These losses are directly related
with the reduction of turbine efficiency. In order to provide a new design methodology for reducing losses and increasing
turbine efficiency, a two-dimensional axial-type turbine blade shape is modified by the optimization process with two-dimensional
compressible flow analysis codes, which are validated by the experimental results on the VKI turbine blade. A turbine blade
profile is selected at the mean radius of turbine rotor using on a heavy duty gas turbine, and optimized at the operating
condition. Shape parameters, which are employed to change the blade shape, are applied as design variables in the optimization
process. Aerodynamic, mechanical and geometric constraints are imposed to ensure that the optimized profile meets all engineering
restrict conditions. The objective function is the pitchwise area averaged total pressure at the 30 % axial chord downstream
from the trailing edge. 13 design variables are chosen for blade shape modification. A 10.8 % reduction of total pressure
loss on the turbine rotor is achieved by this process, which is same as a more than 1 % total-to-total efficiency increase.
The computed results are compared with those using 11 design variables, and show that optimized results depend heavily on
the accuracy of blade design. 相似文献
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The technical problems of flow measurement in hypersonic flight could be mitigated through dual-rotor turbine flowmeters (DRT-FMs). In this study, a visual experiment platform was designed to reproduce the flow of a 1.3 cm diameter DRT-FM. A mathematical model considering two rotors was developed to perform a parameterised study and evaluate the rotor responses. Further, the entire flow passage was numerically simulated through an added automatic iterative rotor-dynamic calculation based on the angular momentum balance theory. According to the experimental results, the response range of the rotational speeds was divided into three stages: unresponsive, unstable, and stable. The downstream rotor responded at a lower flow rate, increasing the measurement range of the rotor turbine flowmeter. Considering the region of linear increase in the rotor speed in stable state under different flow media, tip clearances, and number of blades, the mathematical results indicated that the downstream rotor exhibited a compensation effect of the rotational speed on the calculation of rotational speed at the current flow rate conditions, which mitigates the measurement instability of the upstream rotor. Through the simulations, the rotation speed difference of the two rotors resulted in a slight periodic disturbance to the downstream rotor, which was alleviated after flowing through the spacer and could be ignored. Moreover, the high vorticity regions appeared around the rotors and areas of abrupt structural changes in the flow passage; the distribution gradually extended as the vorticity decreased. The present study provides an understanding of the DRT-FM and some recommendations to improve its characteristics. 相似文献
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提出核电汽轮机转子在低周疲劳与高周疲劳交互作用下裂纹扩展寿命的计算与评定方法。介绍核电汽轮机转子的低周疲劳与高周疲劳的应力幅与应力范围、低周疲劳裂纹扩展寿命与高周疲劳扩展寿命的计算方法。给出了核电汽轮机转子在低周疲劳与高周疲劳交互作用下裂纹扩展日历寿命的计算与评定方法,以及1 000 MW级核电汽轮机焊接低压转子疲劳裂纹扩展日历寿命的计算与改进的应用实例。结果表明,高周疲劳对汽轮机转子疲劳裂纹扩展日历寿命有比较大的影响,新研制核电汽轮机的转子结构设计和在役核电汽轮机的转子安全性评定,需要评估转子在低周疲劳与高周疲劳交互作用下裂纹扩展 寿命。 相似文献
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Yean-Ren Hwang Yu-Da Shen Kuo-Kuang Jen 《Journal of Mechanical Science and Technology》2008,22(3):497-505
Air motors are widely used in the automation industry due to special requirements, such as spark-prohibited environments,
the mining industry, chemical manufacturing plants, and so on. The purpose of this paper is to analyze the behavior of a vane-type
air motor and to design a model reference adaptive control (MRAC) with a fuzzy friction compensation controller. It has been
noted that the rotational speed of the air motor is closely related to the compressed air’s pressure and flow rate, and due
to the compressibility of air and the friction in the mechanism, the overall system is actually nonlinear with dead-zone behavior.
The performance of the previous controllers implemented on an air motor system demonstrated a large overshoot, slow response
and significant fluctuation errors around the setting points. It is important to eliminate the dead-zone to improve the control
performance. By considering the effects of the dead-zone behavior, we have developed an MRAC with fuzzy friction compensation
controller to overcome the effect of the dead-zone. The following experimental results are given to validate the proposed
speed control strategy. 相似文献
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Yu-Ta Shen Yean-Ren Hwang Chia-Sheng Cheng 《Journal of Mechanical Science and Technology》2009,23(11):3005-3012
Air motors are often applied in the automation industry in areas with special requirements, such as in spark-prohibited environments,
the mining industry, chemical manufacturing plants, and similar locations. The purpose of this study is to analyze the behaviors
of a ball screw table powered by a vane-type air motor and to design a robust sliding mode controller for the inlet pressure.
The rotational speed of the air motor is closely related to the pressure and flow rate of the compressed air. Furthermore,
the compressibility of the air and the friction in the mechanism mean that the overall system is nonlinear, with fluctuating
input. A robust sliding mode control is developed to overcome the effects of variations in the inlet pressure and air leakage
problems. The experimental results validate the robustness of the proposed position control strategy. 相似文献
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This work is devoted to the evaluation of the influence of the curve shape of the ineradicable initial deflection of a two-span rotor with the residual imbalance on the transition vibration amplitudes at low critical speeds under the rundown. The model corresponds to a high-pressure rotor–combined mid-low-pressure rotor (HPR–MLPR) system of a turbine unit. It is assumed that rotors are connected by a rigid coupling and installed on anisotropic elastic damper supports. It is supposed that the resulting deflection (bend) of this system is formed as a result of the fact that a high-pressure rotor acquires the initial deflection during the operation or because of abnormal launch conditions, the curve shape of which for a load-free rotor is known. The influence of the mutual arrangement of the residual imbalances of rotors and the imbalances caused by the resulting deflection of shafting in a system on the amplitudes of its transition vibration under the rundown of a turbine unit has been studied for two shapes of the initial rotor deflection curve that have the highest and lowest values of the shape parameter. The values of the initial rotor bending deflection and the residual imbalance of both rotors have been set equal to the maximum acceptable values for the operation of a turbine unit. Amplitude calculations have been performed for rotors of a K-300-23.5 Leningrad Mechanical plant (LMZ) turbine. 相似文献
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350 t转子超速动平衡试验站用于大型汽轮机发电设备和大型核能发电设备上转子的超速动平衡试验。本文对上海电气350 t转子超速动平衡试验站在建设过程中的设计、制造、安装、调试环节进行了介绍。 相似文献
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Water droplet erosion is one of major concerns in the design of modern large fossil steam turbines because it causes serious
operational problems such as performance degradation and reduction of service life. A new erosion model has been developed
in the present study for the prediction of water droplet erosion of rotor blades operated in wet steam conditions. The major
four erosion parameter ; impact velocity, impacting droplet flow rate, droplet size and hardness of target are involved in
the model so that it can also be used for engineering purpose at the design stage of rotor blades. Comparison of the predicted
erosion rate with the measured data obtained from the practical steam turbine operated for more than 90.000 hours shows good
agreement. 相似文献
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Mohammad Dadkhah Yousef Hojjat Mehdi Modabberifar Toshiro Higuchi 《The International Journal of Advanced Manufacturing Technology》2009,43(3-4):211-216
In this paper, the design and fabrication of a rotational electrostatic motor with air bearing is presented. Electrostatic motors have many advantages such as convenient fabrication and compact size. In this study, the rotor is a Plexiglas disc with 38-mm diameter and 1-mm thickness and stator is a round set of electrodes etched by standard printed circuit board technique. Plexiglas was used in laser disc optical media and has been developed for use in CDs and DVDs. To reduce the friction between the rotor and the stator, an air bearing is used. Also, in this paper, kinetics of the motion, design, and fabrication process of a prototype is described and then some parameters influencing motor operation are experimentally investigated; experimental results show successful motor operation. In addition, high rotational velocity and optimum acceleration are achieved throughout the operation of the motor. 相似文献
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以当前广泛应用的汽轮机冷态滑参数启动过程为重点研究工况,建立汽轮机转子的全尺寸有限元分析模型.并采用加载等效质量块的方法对其进行简化;采用工程热力学及传热学知识对汽轮机转子边界蒸汽温度和各部位的对流放热系数进行计算.将其作为边界条件加载到汽轮机转子有限元模型上。通过有限元分析软件ANSYS对转子进行温度场的计算与分析,得到温度分布规律、温差最大时刻及出现的部位;采用热应力间接耦合分析法对转子的应力场进行计算分析,得到其应力分布变化情况、等效应力最大值及出现的时刻和部位。根据分析计算结果对汽轮机在使用时应注意的问题提出了合理化建议。 相似文献
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Choon-Yeol Lee Jae-Do Kwon Young S. Chai Ki-Sang Jang 《Journal of Mechanical Science and Technology》2000,14(2):207-214
Fracture phenomenon has been reported on blades, rotors, connections and rotor discs of LP turbines of nuclear power plants, which is caused by fatigue, stress corrosion and erosion. In this study, as a tool of reliability evaluation, a number of stress and fracture analyses were performed on the defected area under various operating conditions using the finite element method. Possible defects on key-way and rotor disc were assumed to be two-dimensional cracks and centrifugal force, temperature distribution and shrink-fit effect were included as external loads. From stress analysis results, stress intensity factors were obtained and these values can be utilized to evaluate reliability and predict remaining lifetime of the turbine discs. 相似文献
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Evaluation of impact dynamics and contact forces in a hydropower rotor due to variations in damping and lateral fluid forces 总被引:1,自引:0,他引:1
Rolf. K. Gustavsson Jan-Olov Aidanp 《International Journal of Mechanical Sciences》2009,51(9-10):653-661
Damages due to contact between the runner and the discharge ring have been observed in several hydroelectric power units. The damage can cause high repair costs of the runner and the discharge ring as well as considerable production losses.In this paper a rotor model of a 45 MW hydropower unit is used for the analysis of the rotor dynamical phenomena occurring due to contact between the runner and the discharge ring for different grades of lateral force on the turbine and bearing damping. The rotor model consists of a generator rotor and a turbine, which is connected to an elastic shaft supported by three isotropic bearings. The discrete representation of rotor model consists of 32 degrees of freedom; to increase the speed of the analysis, the size of the model was reduced with the IRS method to a system with 8 degrees of freedom.Results are presented in bifurcation diagrams, maximum contact force, Poincaré map and phase portrait. Simulations indicate that the contact forces between the turbine and the discharge ring are large, with considerable risks for serious damage as a consequence. The analysis shows that the risk for contact and damage are large for relatively small lateral turbine loads when the gap between the turbine and the discharge ring is small and the contact stiffness is high. 相似文献
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从挠性转子的动平衡方程出发,以660 MW汽轮机转子为例,介绍了挠性转子的低速动平衡的原理与方法。 相似文献