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Reliability design method for steam turbine blades
SHI Jinyuan
Front. Energy. 2008, 2 (4): 363-368.
https://doi.org/10.1007/s11708-008-0073-7
Based on theories of probability and statistics, and taking static stresses, dynamic stresses, endurance strength, safety ratios, vibration frequencies and exciting force frequencies of blades as random variables, a reliability design method for steam turbine blades is presented. The purport and calculation method for blade reliability are expounded. The distribution parameters of random variables are determined after analysis and numerical calculation of test data. The fatigue strength and the vibration design reliability of turbine blades are determined with the aid of a probabilistic design method and by interference models for stress distribution and strength distribution. Some blade reliability design calculation formulas for a dynamic stress design method, a safety ratio design method for fatigue strength, and a vibration reliability design method for the first and second types of tuned blades and a packet of blades on a disk connected closely, are given together with some practical examples. With these methods, the design reliability of steam turbine blades can be guaranteed in the design stage. This research may provide some scientific basis for reliability design of steam turbine blades.
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Computation model for corrosion resistance of
nanocrystalline zircaloy-4
ZHANG Xiyan, ZHU Yutao, LIU Qing, LUAN Baifeng, HUANG Guangjie, LI Cong, ZHANG Xiyan, SHI Minghua, LIU Nianfu, ZHANG Xiyan, LI Cong
Front. Energy. 2008, 2 (4): 386-389.
https://doi.org/10.1007/s11708-008-0102-6
A computation model of the corrosion rate versus grain size of nanocrystalline zircaloy-4 was presented. The influence of the second phase on the conductivity of alloy was considered. By this model, the corrosion rate of nanocrystalline zircaloy-4 at different temperature was calculated. The results show that the corrosion rate constant and weight gain of nanocrystalline zircaloy-4 decrease with the decrease of grain size, and that the corrosion weight gain of nanocrystalline zircaloy-4 is less than that of zircaloy-4 of coarse grain. The computational result is coincident with the experimental result.
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Centrifugal compressor blade optimization based
on uniform design and genetic algorithms
SHU Xinwei, GU Chuangang, XIAO Jun, GAO Chuang
Front. Energy. 2008, 2 (4): 453-456.
https://doi.org/10.1007/s11708-008-0083-5
An optimization approach to centrifugal compressor blade design, incorporating uniform design method (UDM), computational fluid dynamics (CFD) analysis technique, regression analysis method and genetic algorithms (GA), is presented. UDM is employed to generate the geometric information of trial samples whose performance is evaluated by CFD technique. Then, function approximation of sample information is performed by regression analysis method. Finally, global optimization of the approximative function is obtained by genetic algorithms. Taking maximum isentropic efficiency as objective function, this optimization approach has been applied to the optimum design of a certain centrifugal compressor blades. The results, compared with those of the original one, show that isentropic efficiency of the optimized impeller has been improved which indicates the effectiveness of the proposed optimization approach.
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Gas dynamic characteristic of displacer in Stirling
cryocoolers
LIU Xinguang, LIU Dongyu, WANG Yong, WU Yinong
Front. Energy. 2008, 2 (4): 499-503.
https://doi.org/10.1007/s11708-008-0090-6
Based on the vector analysis of the dynamic characteristic of the displacer in split-type Stirling cryocoolers, experimental study was performed on a 2 W@80 K cooler to uncover the relationship among pressure fluctuation, damped impedance, inherent frequency, cold-tip temperature and the cooling performance. The result shows that the pressure amplitude and phase shift between pressure and displacer motion decrease when the cooling temperature decreases; the dynamic damp of the displacer increases at lower cooling temperature, which results in the increase of pressure drop of the regenerator, the decrease of average pressure of the cold cubage, the decrease of gas dynamic pressure, the decrease of phase shift between pressure and displacer motion, and the displacement of the regenerator and the PV power; at lower cooling temperature, the inherent frequency of the displacer increases because of the augmentation of gas spring constant. And as the inherent frequency is getting closer to the operating frequency, the drive current of the motor decreases; the piston of the compressor affects the displacer by the pressure fluctuation engendered by its motion, and the displacer reacts by changing the mass and momentum distribution to adjust the gas spring constant and the damp coefficient.
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36 articles
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