Bo L.,Xi'an Jiaotong University |
Bo L.,XiAn Shaangu Power Co. |
Ying J.,XiAn Shaangu Power Co. |
Yuping C.,XiAn Shaangu Power Co.
Proceedings - 9th International Conference on Measuring Technology and Mechatronics Automation, ICMTMA 2017 | Year: 2017
In order to enhance operation safety of unit, at present, state monitoring of large-scale rotary machine has been universally applied. Failure diagnosis technology receives universal emphasis and it is continually developing from machine maintenance at fixed time to maintenance according to actual condition. With the development in communication and network technology, people are no longer satisfy with diagnosis technology of single machine, and they hope diagnosis technology can be share by all so as to solve more and more machine failure. So networking has become to be the inevitable trend for the development of diagnosis technology. Failure diagnosis and maintenance decision auxiliary system of large-scale turbine unit is one distributed network system towards the whole enterprises, it makes networking on 18 sets of large-scale tribune compressor unit of enterprises. System can not only make online monitoring and failure diagnosis on operation state of theses machines, but also it can provide the basic state and artificial monitoring information at fixed time, it combines with vibration data, process parameter and existing artificial periodic monitoring information together to realize periodic evaluation of machine at normal state and comprehensive failure diagnosis analysis at abnormal state, so it provides important base for the early failure discovery and maintenance decision of machine. It fundamentally changes the backward key unit inspection as well as maintenance management way and increases management level of equipment. © 2017 IEEE.
Huang P.X.,Hi Bar MC Technologies LLC |
Yin J.,Xian ShaanGu Power Co.
Proceedings of the ASME Turbo Expo | Year: 2014
High-speed high-pressure ratio compressor surge is a transient breakdown in compression accompanied by an abrupt momentary reversal of gas flow. It commonly exists in dynamic type turbo compressors, particularly in the axial compressor of modern aero-engines. By Newton's Laws of Motion, a force is needed to change the state of any motion. So what is the force that can cause such a dramatic motion as surge? What exactly triggers it, and how do we quantify the transient surge phenomenon? This paper attempts to answer these questions and discuss the transient dynamics of surge at its initial stage. It has generally been accepted that surge is precipitated by the onset of a rotating spike or stall, not only for low speed but for high-speed compressors too. The state of dynamic surge modeling today is best exemplified by the "Greitzer-Moore" model. However, it fails to incorporate the key elements of the transient nature of a surge inception: The extremely short time duration on millisecond scale and the shock wave presence observed experimentally. An indirect approach is taken in this paper to address the transient dynamics of stall and surge by using an analogy to the shock tube. The link is established based on observations that instant zero net through flow inside stalled cascade cell triggers stall/surge. The results from the analogy reveal that surge initiation simultaneously generates a pair of non-linear compression and expansion waves (CW & EW) and induced reverse fluid flow (IRFF). The dynamic forces for instant flow reversal are the pushing force of upstream propagating CW and the pulling force from downstream travelling EW. Surge Rules are deduced and then compared with experimental findings by previous researchers with good agreements. Moreover, the strength of the transient post-surge components, CW, EW and IRFF, can be estimated analytically or numerically by the shock tube theory from known pre-surge conditions and routes to surge. © 2014 by ASME.
Huang P.X.,Hi Bar MC Technologies LLC |
Yin J.,Xian ShaanGu Power Co.
Proceedings of the ASME Turbo Expo | Year: 2013
Compressor surge is a complete breakdown in compression resulting in an abrupt momentary reversal of gas flow and the violent pressure fluctuation with relatively low frequency and high amplitude. It commonly exists in dynamic type turbo compressors, particularly axial compressor and jet engine, or turbo charger for reciprocating engines. It is generally accepted that surge is preceded by a rotating stall, a situation of a few stalled blades rotating around compressor annulus (cascade) with much higher frequency. In jet engine, violent surge event typically produces a frightening loud bang, lots of vibrations and could cause catastrophic structural failures if not timely managed. Naturally, as important matters as rotating stall and surge, there have been tremendous R/D efforts from academia, government and industry devoted to this area, especially since jet engines became the prime powerhouses for modern airplanes. Despite of all the efforts, there still seems to be a more urgent need to understand the physical characteristics of the transition from a rotating stall to surge that has mystified researchers due to its transient nature. Fundamental questions remain unanswered even today, such as: What exactly triggers the surge to take place from a rotating stall? What is the physical nature of a compressor system or a local incipient surge: is it a movement of wave or fluid particles or both? How to estimate the quantitative destructive forces of a severe surge, that is, the maximum possible surge strength? This paper attempts to answer these questions by applying the classical Shock Tube Theory to the transient process from rotating stall to surge. The Shock Tube analogy is established with the hypothesis (implied from experimental observations) that an instant zero through flow condition exists inside a stalled cascade cell or dynamic compressor that triggers surge. It is revealed that surge event consists of a pair of non-linear compression and expansion waves (CW & EW) that instantly reverse gas flow (IRFF) by the pushing force of upstream propagating CW and the pulling force from downstream travelling EW. The surge strength is shown to be proportional to the square root of the pressure ratio of the involved cascade or compressor. Surge Rules are deduced to predict the location of surge initiation, the minimum and maximum surge strengths, travelling directions and speed. Moreover, a pro-active control strategy called SEWI (Surge Early Warning Initiative) is proposed using the unique characteristics of CW-IRFF-EW formation of a cascade cell induced surge as precursors for subsequent warning and controls before the destructive compressor surge takes place. Copyright © 2013 by ASME.
Guo B.,Harbin Institute of Technology |
Zhao Q.,Harbin Institute of Technology |
Li H.,Xian Shaangu Power Co.
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | Year: 2014
The ultra-precision wheel normal grinding of binderless tungsten carbide aspheric mold is researched. The influence of grinding wheel initial position error on grinding accuracy is analyzed. The ground surface morphology and quality of binderless tungsten carbide aspheric are presented. And then, the grinding error compensation is optimized and the subsurface damage of mold is studied by focus ion beam. The results show that the grinding wheel initial position error model is useful to enhance the grinding wheel initial position accuracy. The morphology and quality of binderless tungsten carbide aspheric surface are inhomogeneous. The surface quality of aspheric center is better than that of aspheric edge round. Finally, after 3 times error compensation, there binderless tungsten carbide aspheric molds with 0.3 μm (PV) form accuracy and 8 nm (Ra) surface roughness are obtained, and no crack is found in subsurface of these molds. © 2014 Journal of Mechanical Engineering.
Guo B.,Harbin Institute of Technology |
Zhao Q.,Harbin Institute of Technology |
Li H.,XiAn Shaangu Power Co.
International Journal of Advanced Manufacturing Technology | Year: 2014
In aerospace industry, TiC-based cermet hemisphere couples are widely used as dry sliding bearing and gyro due to its high resistance to wear and heat. To enhance the grinding precision, this paper presents an ultraprecision grinding technique for machining TiC-based cermet hemisphere couples. The factors affecting the form and dimension accuracy of the hemisphere couples in ultraprecision grinding were analyzed theoretically. The optimization of grinding conditions and ground surface morphology of TiC-based cermets were investigated. In addition, the subsurface damage of ground TiC-based cermet hemisphere couples was observed by focused ion beam FIB. The research results show that position errors have more significant impact on concave in grinding of hemisphere couples. The TiC-based cermet ground surface revealed a smooth surface covered by micropits, traces, and reliefs because of the special material properties, and the surface roughness could be improved by the decrease of feed rate, while the different feed rates did not influence form accuracy. Finally, TiC-based cermet hemisphere couples with 16 nm surface roughness, 0.3 μm PV form accuracy, radius deviation of less than 3 μm, and subsurface damage depth of less than 2.5 μm were obtained. © 2014 Springer-Verlag London.
Wang Y.-T.,Xi'an Jiaotong University |
Wang Y.-T.,Xian Shaangu Power Co. |
Wang D.,Xian Shaangu Power Co. |
Xu J.,Xian Shaangu Power Co. |
Huang S.-J.,Xi'an Jiaotong University
Kung Cheng Je Wu Li Hsueh Pao/Journal of Engineering Thermophysics | Year: 2010
This paper mainly focuses on the design of an axial compressor with features of high humidity ratio, high pressure ratio and extremely low pressure for a certain project. The medium of the compressor is exhausted gas, which has complex constituents and high humidity. The compressor has a wide range of operating conditions. The pressure ratio is 2~55, the inlet pressure is 2~50 kPa(a), the inlet temperature is 5~40°C. The gas is always in a saturated condition, and the nature of the gas is varied by inlet conditions at all time. The influence of low Reynolds number and high humidity on the performance of the compressor has been studied in detail in this paper. The compressor is mainly characterized by wide range of parameters of medium, high humidity, low Reynolds number. Considering the low Reynolds number and wide change of parameters, we replace the exhausted gas with air to simplify the design. The design of two axial compressors matching in tandem also has been studied. The optimized approaches and solutions concluded in this paper could be taken as a good reference for the design and optimization of similar compressors.
Wen G.,Xi'an Jiaotong University |
Li Y.,Xi'an Jiaotong University |
Liao Y.,Xi'an Jiaotong University |
Liao Y.,Xian Shaangu Power Co. |
He Q.,Xi'an Jiaotong University
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | Year: 2013
A faulty rotor system vibration acceleration signal integration method based on precise information reconstruction is proposed in this paper by summarizing the advantages and disadvantages of current integration method both in time domain and frequency domain. This method utilizes the characteristic structure of the faulty rotor system vibration signal, which is mainly composed of the rotational frequency and its superharmonic and/or subharmonic frequency components. The fast Fourier transform is performed to the acceleration signal to get its spectrum, then the characteristic frequency components are searched. Comparing the amplitudes of all the extracted components with a threshold set by SNR. The components, whose amplitudes are below the threshold, will be considered as noise components and will be discarded and only those whose amplitudes are above the threshold will be reserved. The high-accuracy spectrum correction is then made with those components reserved to get the precise information, including frequency, amplitude and phase information, needed for the integration and signal reconstruction. The velocity signal and displacement signal are therefore reconstructed with the precise information of all the reserved components. Precise Information Reconstruction is excellent at removing the broadband noise. The reliability and effectiveness of the proposed method are testified by the simulation analysis and the application examples. © 2013 Journal of Mechanical Engineering.
Lin L.,University of Science and Technology Beijing |
Wang X.,North China Electrical Power University |
Wang Z.,Xian Shaangu Power Co.
Yingyong Jichu yu Gongcheng Kexue Xuebao/Journal of Basic Science and Engineering | Year: 2012
Based on selecting the proper formulas of thermal conductivity and viscosity for nanofluids, a three-dimensional fluid-solid conjugated model was developed to analyze the effect of the heat sink structure, the nanoparticle kind, diameter and volume fraction, and the base fluid kind on the cooling performance of microchannel heat sink. The results showed that: (1) thermal dispersion effect caused by nanoparticle random motion enhanced the thermal convection of nanofluid thus enhances significantly the cooling performance of heat sink; (2) the enhancement of nanofluids was closely dependent on the heat sink structure and the dependence was distinct from the pure fluid, hence the heat sink structure was needed to be optimized for nanofluids as coolants; (3) as the nanoparticle volume fraction increases, the thermal resistance reduced and the pressure increased, the water-based Al 2O 3 nanofluid with 0.5% volume fraction was the optimal coolant which caused 10.1% decrease in the thermal resistance and only 0.38% increased in the pressure drop; (4) although the nanoparticle size had a small effect on the thermal resistance, nanoparticles with small diameter were recommended with consideration of stability of nanofluids; (5) Al 2O 3 nanoparticle was superior to TiO 2 and CuO, and water was the better base fluid than ethylene glycol and engine oil.
Liu Y.,Northwestern Polytechnical University |
Liu Y.,XiAn Shaangu Power Co. |
Liu L.-G.,XiAn Shaangu Power Co. |
Wang H.,XiAn Shaangu Power Co.
Chinese Physics Letters | Year: 2012
The small-world network model represented by a set of evolution equations with time delay is used to investigate the nonlinear dynamics of networks, and the nature of instability phenomena in traffic, namely, congestion and bursting in the networks, are studied and explained from bifurcation analysis. Then, the governing equation in the vector field is further reduced into a map, and the ensuing period-doubling bifurcation, sequence of period-doubling bifurcation and period-3 are studied intuitively. The existence of chaos is verified numerically. In particular, the influences of time delay on the nonlinear dynamics are presented. The results show that there are a rich variety of nonlinear dynamics related to the intermittency of the traffic flows in the system, and the results can gain a fundamental understanding of the instability in the networks, and the time delay can be used as a key parameter in the control of the systems. © 2012 Chinese Physical Society and IOP Publishing Ltd.
Liu J.-S.,Xi'an University of Architecture and Technology |
Yuan S.-C.,Xi'an University of Architecture and Technology |
Jiang X.-K.,Xi'an University of Architecture and Technology |
Zhang Q.-Y.,Xian Shaangu Power Co.
Guangdianzi Jiguang/Journal of Optoelectronics Laser | Year: 2010
A novel BP neural network on camera calibration approach is proposed based on Zernike moment and particle swarm optimization algorithm. First to improve the accuracy of training data, the subpixel coordinates of circular centers are detected by Zernike moment and curvature preserving. And secondly optimal weights and thresholds of neural networks are optimized by PSO algorithm to improve convergence rate and generalization ability. The experiments show that the errors are less than 0.06 mm in the X and Y axis direction and the root-mean-square error of test set is merely 0.194 mm, which indicate that the technique is feasible and effective.