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Wang Y.,Huazhong University of Science and Technology | Deng C.,Huazhong University of Science and Technology | Wu J.,Huazhong University of Science and Technology | Wang Y.,China Chang Jiang Energy Corporation | Xiong Y.,Ship Research Institute
Engineering Failure Analysis | Year: 2014

Corrective maintenance is a maintenance task performed to identify and rectify the cause failures for a failed system. The engineering equipment gets many components and failure modes, and its failure mechanism is very complicated. Failure of system-level might occur due to failure(s) of any subsystem/component. Thus, the symptom failure of equipment may be caused by multilevel causality of latent failures.This paper proposes a complete corrective maintenance scheme for engineering equipment. Firstly, the FMECA is extended to organize the numerous failure modes. Secondly, the failure propagation model (FPM) is presented to depict the cause-effect relationship between failures. Multiple FPMs will make up the failure propagation graph (FPG). For a specific symptom failure, the FPG is built by iteratively searching the cause failures with FPM. Moreover, when some failure in the FPG is newly ascertained to occur (or not), the FPG needs to be adjusted. The FPG updating process is proposed to accomplish the adjustment of FPG under newly ascertained failure. Then, the probability of the cause failures is calculated by the fault diagnosis process. Thirdly, the conventional corrective maintenance recommends that the failure with the largest probability should be ascertained firstly. However, the proposed approach considers not only the probability but also the failure detectability and severity. The term REN is introduced to measure the risk of the failure. Then, a binary decision tree is trained based on REN reduction to determine the failure ascertainment order. Finally, a case is presented to implement the proposed approach on the ram feed subsystem of a boring machine tool. The result proves the validity and practicability of the proposed method for corrective maintenance of engineering equipment. © 2013 Elsevier Ltd.


Xia L.,Hubei Engineering University | Long W.,Hubei Engineering University | Zhang Y.S.,Hubei Engineering University | Huang J.,Hubei Engineering University | Hu B.S.,China Chang Jiang Energy Corporation
Advanced Materials Research | Year: 2014

Effect of particle size of Al(OH)3 and Mg-containing modifier of binder and hardener on the dry strength and storage stability of high neutralization degree phosphate-bonded no-bake sand were studied. Results show that particle size of Al(OH)3 has little effect on the dry strength and storage stability when its varieties are 4.552 μ m toothpaste-grade Al(OH)3 and 6.136μm industrial special Al(OH)3, 6.136μm industrial special Al(OH)3 is more appropriate in consideration of cost and source. Adding Mg-containing modifier to binder code 32B8M15B cannot improve the dry strength and storage stability, but adopting compound modifier, 2% fused magnesia powder+2% iron powder+4% copper powder,can obtain better properties, dry strength can reach 3.022MPa, and the minimum strength is above 1MPa with humidity fluctuation from 21%RH to 60%RH in 18 days. © (2014) Trans Tech Publications, Switzerland.


Yin D.,China Chang Jiang Energy Corporation | Zhao W.,China Aerospace Science and Technology Corporation | He Y.,China Chang Jiang Energy Corporation | Xiao C.,China Chang Jiang Energy Corporation | Hu B.,China Chang Jiang Energy Corporation
International Conference on Power Engineering 2013, ICOPE 2013 | Year: 2013

Based on a new type independent developed driven turbine blades of 237 mm, the stress of single blade under several different speeds within the rated speed range is calculated by large-scale FEA software, and then the strength of the blade is analyzed, and the rationality of boundary conditions is validated. At the same time, according to cyclic symmetry principle, the full circle blades frequency is calculated, the Campbell diagram is drawn, and the "triple point" vibration analysis is made to the blades. The results show the design method is reasonable and the blades meet the capability specifications.


Zhang X.,China Chang Jiang Energy Corporation | Wu Z.,China Aerospace Science and Technology Corporation | Hu L.,China Chang Jiang Energy Corporation | Hu B.,China Chang Jiang Energy Corporation | And 2 more authors.
International Conference on Power Engineering 2013, ICOPE 2013 | Year: 2013

The investigation of aerodynamic characteristic of control stage is important as its aerodynamic performance deeply affects the economic performance of steam turbines, especially for medium and small power back-pressure turbines. In this paper, the single control stage of a specific high-temperature and high-pressure steam turbine was investigated using CFD (Computational fluid dynamics) method. The flow characteristics and aerodynamic performance of the steam admission section including the main control valves, connecting pipes, regulating valves, nozzle group and rotor blades, were numerically simulated and analyzed. The aerodynamic performance of the control stage subjected to varied operating conditions has been achieved. Distribution of flow parameters and the location of energy loss within control stage have also been achieved, which clearly indicates the non-axial symmetric flow characteristics of control stage. The variation of flux and efficiency of the control stage as a function of the pressure ratio are plotted.


Pan J.,Huazhong University of Science and Technology | Huang Y.,China Chang Jiang Energy Corporation | Gao W.,Huazhong University of Science and Technology | Zhang Y.P.,Huazhong University of Science and Technology
Applied Mechanics and Materials | Year: 2014

The power generation system using Organic Rankine Cycle (ORC) is a new technology for energy recovery, but very few people have studied the control system of the organic working fluid turbine at present. This paper put forward the speed and power control strategy about the organic working fluid turbine. The parameters of the speed and power regulators are tuned to insure the steady of speed and power. A series of dynamic simulation experiments are carried out in Simulink. Through the simulation research of robustness and load disturbance experiments, the designed control system have a good effect on accuracy and dynamic response. © (2014) Trans Tech Publications, Switzerland.

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