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Lang G.,Xian Jiaotong University | Liao Y.,Xian Jiaotong University | Liao Y.,Xian Shaangu Power Co. | Liu Q.,Xian Jiaotong University | Lin J.,Xian Jiaotong University
Journal of Sound and Vibration | Year: 2015

The vibration responses of different linear faults all possess some common features, which make fault diagnosis very difficult. Based on the multi-sensor information fusion theory, this paper presents a new qualitative identification method for the diagnosis of linear faults. The excitation-response dynamic equation is constructed and system balancing response with full consideration of system anisotropy is analyzed. Through discussion of the precession orbit shape difference and its dispersive situation, the orbit shape average difference coefficient and the corresponding dispersion term are estimated to obtain the theoretical balancing effect. Finally, the qualitative identification of linear fault can be done according to whether the calculated balancing effect meets the safe operation requirement or not. The dynamic characteristic of the system difference coefficients is verified by a simulation experiment and the case study further testifies the capability and reliability of the proposed method. © 2014 Elsevier Ltd. All rights reserved. Source

Li J.,Xian University of Technology | Chao L.,Xian University of Technology | Xu J.,Xian Shaangu Power Co. | Zhang M.,Xian University of Technology
Zhongguo Jixie Gongcheng/China Mechanical Engineering | Year: 2012

Stress and deformation of a welded TRT volute by static load and water pressure were stimulated initially with the method of elastic-plastic finite element method. The results show that the function of the whole volute's stress value in the static load is not big. The greatest stress is 19.1MPa and in terms of constraint place the maximum equivalent stress is mainly concentrated. The maximum displacement is 0.0776mm in the whole volute and, it appears in lower shell in supporting pole.In water pressure test, the whole volute stress value is all between 40 to 85MPa, only local small-scale is reached 382MPa. Under the action of water pressure, maximum overall displacement of the whole cabinet appears on export baffle, and the value is 1.511mm. Deformation in the volute is not remarkable. Source

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. Source

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. Source

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. Source

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