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Wang X.J.,Harbin Institute of Technology | Wang N.Z.,Harbin Institute of Technology | Wang L.Y.,Harbin Turbine Company Ltd | Hu X.S.,Harbin Institute of Technology | And 3 more authors.
Materials and Design

The novel stir casting assisted by ultrasonic treatment processing was studied. Unlike traditional stir casting, short semi-solid stir time was needed for addition and pre-dispersion of the particles in the novel processing. For ultrasonic treatment, there existed an optimal time. Both too short and too long time for the treatment resulted in nonhomogeneous particle distribution. Furthermore, the liquid stirring after ultrasonic treatment was proved to be necessary to further improve particle distribution. The mechanical properties of the composites fabricated by different parameters indicated that ultrasonic treatment evidently improved the mechanical properties compared with traditional stir casting. 5-20% SiCp/AZ91 composites were fabricated by the novel processing. The particle distribution was uniform in these composites. The grains were refined by addition of SiC particles. Grain sizes of composites decreased with the increases of particle contents. The ultimate tensile strength, yield strength and elastic modulus were enhanced as the particle contents increased. © 2014 Elsevier Ltd. Source

Bin G.-F.,Beijing University of Chemical Technology | Bin G.-F.,Hunan University of Science and Technology | He L.-D.,Beijing University of Chemical Technology | Gao J.-J.,Beijing University of Chemical Technology | Li L.-B.,Harbin Turbine Company Ltd
Zhendong yu Chongji/Journal of Vibration and Shock

Using the conventional influence coefficient method and a high-speed dynamic balancing machine is usually difficult to balance some large flexible rotors, a new method for LP rotor balancing of a large steam turbine based on modal shape analysis was developed here. Analyzing the rotor system structure and considering the dynamic characteristics of a dynamic balancing machine, a rotor-bearing-pedestal system model was established by using DyRoBeS software to get its critical speeds and modal shape. Then, a reasonable balance process including balancing planes and rotating speed points was designed based on modal shapes combined with the influence coefficient method of a flexible rotor. The balancing method of order by order was adopt to meet dynamic balancing requirements of this kind of large rotors. Finally, a large 660 MW steam turbine LP-rotor produced by Harbin Turbine Company Limited was taken as an example. The results showed that using the proposed method can balance a large flexible rotor effectively, and reduce balancing times, and save balancing cost. Source

Wang Y.-L.,Dalian Maritime University | Sun L.-Q.,Harbin Turbine Company Ltd | Cui Y.,Dalian Maritime University | Han Y.,Dalian Maritime University
Hangkong Dongli Xuebao/Journal of Aerospace Power

In order to study the dynamics similarily of actual rotor system with gyroscopic effect similar to the corresponding scaled model, the dynamic similarity criteria for rotor-support system considering gyroscopic moment were derived by using dimensional analysis method, and the similarity ratios of physical variables of actual rotor system and model were obtained. And the correctness of dynamics similarity criteria of rotor system with gyroscopic effect was verified by solving the analytical solution of critical speed for a Jeffcott rotor system at different similarity ratios, and by studying the similarity of critical speeds and modes for an actual rotor system based on the finite element simulation software ANSYS. It shows that the natural frequency of actual rotor system is similar to its scaled model in similarity speed, and the critical speed is similar for rotor system considering gyroscopic moment, simple support and Rayleigh proportional damping. © 2015, BUAA Press. All right reserved. Source

Zhao C.,Harbin Engineering University | Zhao Y.,Harbin Turbine Company Ltd | Jin T.,Harbin Engineering University | Zhang H.,Harbin Engineering University
Harbin Gongcheng Daxue Xuebao/Journal of Harbin Engineering University

Because ZG1Cr10MoWVNbN heat-resistant steel works under high temperature for a long term, its long-term high temperature aging performance is very important. After a test on a sample of long-term aging heat treatment process under 600℃ for 17000 hours, the carbide microstructure's change in performance before and after the aging test were compared, along with the influence of precipitates on mechanical properties. The results show that after the 600℃ long-term aging process, the martensite lath becomes wider, the interface between laths becomes blurred; before and after the aging, the ZG1Cr10MoWVNbN steel's mechanical properties decrease to a varying extent, among which the plastic index and the impact power is reduced more obviously; after the aging, the sizes of NbC carbide granules precipitated are still small, manifesting the main phase after reinforcement under high temperature, it is beneficial to keeping steel's better performance under high temperature, reducing the performance decaying of alloy under high temperature, the precipitated M23C6 carbide becomes coarsened obviously, which leads to worsening of martensite and reducing in strength. ©, 2015, Editorial Board of Journal of HEU. All right reserved. Source

Zhang H.,Harbin Institute of Technology | Zhang H.,Harbin Turbine Company Ltd | Wang X.,Harbin Institute of Technology | Yan P.,Harbin Institute of Technology | Han W.,Harbin Institute of Technology
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering

In order to study the feasibility of the leaf seal replacing the labyrinth seal used in turbine stage, the labyrinth seal of the corresponding parts of one and a half high-pressure turbine stage is replaced by leaf seal, numerical simulation is carried on by using the commercial software CFX, and the result is compared with the original one and a half stage with labyrinth seal. The result shows that, although the simple seal replacement reduces the leakage flow of the seal, but does not reduce the leakage loss of turbine stage, and enhance the interference of the leakage flow to mainstream, the simple design is not feasible. So as to match the leaf seal, the balance hole and the axial gap reasonably, on the basis of the original design, the leaf seal is used as the stator diaphragm seal and the rotor tip seal, and the labyrinth seal is set in the axial gap of the turbine stage. To the final scheme of leaf seal applied to turbine stage, the leaf seal and balance hole achieve reasonable match, and improve the aerodynamic performance, reduce the leakage loss, provide a good inlet condition to the next turbine stage at the same time. © 2014 Journal of Mechanical Engineering. Source

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