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Xie W.-L.,Shanghai JiaoTong University | Wang H.-T.,Shanghai JiaoTong University | Zhu X.-C.,Shanghai JiaoTong University | Zhou D.-W.,Shanghai Turbine Co. | Du Z.-H.,Shanghai JiaoTong University
Shiyan Liuti Lixue/Journal of Experiments in Fluid Mechanics | Year: 2011

The flow structure in a low-pressure exhaust hood model of a stream turbine was investigated using a time-resolved particle image velocimetry (TR-PIV). The velocity vector and the vorticity contours of some characteristic plane of the exhaust hood model were gained through measurement. Several vortexes were observed at the top of the model, and they combined together to form a large passage vortex during flowing down to the outlet. This passage vortex movement played a main role in the flow field of the model with the vorticity of it decreasing gradually. Another invention of the experiment was that baffles arranged at the bottom of the model could compel the fluid to flow along the direction of the mainstream, which would give a positive impact on the improvement of the performance of the exhaust hood.

Jiang P.N.,Shanghai JiaoTong University | Jiang P.N.,Shanghai Turbine Company | Wang W.Z.,Shanghai JiaoTong University | Liu Y.Z.,Shanghai JiaoTong University | Meng G.,Shanghai JiaoTong University
Archive of Applied Mechanics | Year: 2012

A comparative analysis of the influence of steam leakage through vane, gland, and shaft seals on the rotordynamics of the high-pressure rotor of a 1,000 MW ultra-supercritical steam turbine was performed using numerical calculations. The rotordynamic coefficients associated with steam leakage through the three labyrinth seals were calculated using the control-volume method and perturbation analysis. A stability analysis of the rotor system subject to the steam forcing induced by the leakage flow was performed using the finite element method. An analysis of the influence of the labyrinth seal forcing on the rotordynamics was carried out by varying the geometrical parameters pertaining to the tooth number, seal clearance, and inner diameter of the labyrinth seals, along with the thermal parameters with respect to pressures and temperatures. The results demonstrated that the steam forcing with an increase in the length of the blade for the vane seal significantly influences the rotordynamic coefficients. Furthermore, the contribution of steam forcing to the instability of the rotor is decreased and increased with increases in the seal clearance and tooth number, respectively. The comparison of the rotordynamic coefficients associated with steam leakage through the vane seal, gland seal, and shaft seal convincingly disclosed that, although the steam forcing attenuates the stability of the rotor system, the steam turbine is still operating under safe conditions. © 2011 Springer-Verlag.

Wang P.,Shanghai JiaoTong University | He J.,Shanghai Turbine Co. | Liu Y.,Shanghai JiaoTong University
Dongli Gongcheng Xuebao/Journal of Chinese Society of Power Engineering | Year: 2016

The three-dimensional steam flow in control valve system of a nozzle-governing feed-water pump steam turbine was extensively modeled at the rated condition by using computational fluid dynamics (CFD), so as to study the influence of upstream/downstream structures on internal steam flow field in the piping of control valve system when all the valves are open. In simulation, the shear stress transport (SST) model was used to solve the closure problem of classic governing equations, while the multiple reference frame (MRF) method was used to simulate the flow field around the rotor in the governing state, with focus on the pressure loss and flow distribution in different valve passages, and on the flow characteristics of superheated steam in the control valve system; meanwhile, an analysis was conducted to the complicated three-dimensional steam flow patterns in following components, such as in the multi-valve chamber, the diffuser downstream the valve exit and in the tube bends, etc. Results show that the flow capacity of control valve is mainly determined by the quantity of downstream nozzles, which is greatly influenced by the distance from the control valve to the inlet of the valve system. © 2016, Editorial Department of Chinese Society of Power Engineering. All right reserved.

Zhao W.,Shanghai JiaoTong University | Lu F.,Shanghai JiaoTong University | Li Z.,Shanghai JiaoTong University | Wang D.,Shanghai JiaoTong University | And 3 more authors.
Zhongguo Jiguang/Chinese Journal of Lasers | Year: 2014

Stellite6 coating is cladded on the 17-4PH stainless steel using a diode laser. Fatigue behaviors of substrate specimens, as-cladded specimens and the cladded specimens with heat treatment (550 ℃ for 6 h) are tested with the tension and compression loading method. The fracture surface is characterized by scanning electron microscopy (SEM). The results show that the fatigue strength with 107 cycles of substrate specimens is 470 MPa which is higher than that of the as-cladded specimens with 380 MPa, while the fatigue strength of cladded specimens with heat treatment can reach to 440 MPa. The fatigue surface of substrate specimen shows that the fatigue crack initiates at the surface or inner defects, then propagates forward with the parallel fatigue striations and dimple appearance, while the crack of cladded specimens initiates at the defects in the coating or the interface between the coating and the substrate, then extends to the coating which shows the brittle inter-dendritic fracture and the substrate shows the ductile fatigue fracture respectively.

Wang W.Z.,Shanghai JiaoTong University | Liu Y.Z.,Shanghai JiaoTong University | Meng G.,Shanghai JiaoTong University | Jiang P.N.,Shanghai Turbine Company
Journal of Mechanical Science and Technology | Year: 2010

An extensive investigation of influence of rub grooves on dynamics and stability of the rotor, which is subjected to aerodynamic forcing associated with the leakage flow through 44 straight-through seals, was performed by using numerical calculations based on the single control-volume method and the perturbation analysis. Three cases of different groove configurations were chosen for the comparative study, e.g., the seal without rub groove (case1), the seal with upstream shifting of the seal tooth in respect to the rub groove (case2) and the seal with location of the seal tooth in the middle station of the rub groove (case3). The orifice contract coefficient adopted in reduction of rotordynamic coefficients was provided by using Computational Fluid Dynamics (CFD). Influence of rub grooves on the leakage flow was obtained in terms of the close-up view of the flow pattern near the seal tooth, leakage flow rate, distributions of the mean pressure and circumferential velocity in cavities. In comparison to case 1, the leakage flow in case 3 is considerably intensified, while which in case 2 is slightly increased. Dynamics and instability of the rotor in all cases was discussed in terms of the rotordynamic coefficients and the logarithmic decrement, respectively. The results disclosed that the aerodynamic forcing in case 2 intensified the destabilization of the rotor system. © 2010 The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg.

Wang W.Z.,Shanghai JiaoTong University | Liu Y.Z.,Shanghai JiaoTong University | Meng G.,Shanghai JiaoTong University | Jiang P.N.,Shanghai Turbine Company
Journal of Mechanical Science and Technology | Year: 2010

A nonlinear model of flow-structure interaction between steam leakage through labyrinth seal and the whirling rotor was presented. The particular concern was placed on incorporating thermal properties of the steam fluid into the mathematical model. To see the influence of the steam fluid on the whirling rotor, two sets of thermal parameters of the steam fluid, e.g., temperature and pressure drop in each seal cavity, were selected from the typical 1000 MW supercritical and 300 MW subcritical power units in China. The interlocking seal widely employed in practical situations was chosen for study. The rotor-seal system was modeled as a Jeffcott rotor subject to shear stress and pressure force associated with the steam leakage. Spatio-temporal variation of the steam forcing on the rotor surface in the coverage of the seal clearance and the cavity volume was specifically delineated by using the Muzynska model and the perturbation analysis, respectively. The governing equation of rotor dynamics including the influence of the steam leakage was solved by using the fourth-order Runge-Kutta method, resulting in the orbit of the whirling rotor. Stability of the rotor was inspected by using Liapunov's first method. The results showed that the destabilization speed of the rotor was significantly influenced by the steam leakage. © KSME & Springer 2009.

Sun L.,Tsinghua University | Cai Z.,Tsinghua University | Pan J.,Tsinghua University | Liu X.,Shanghai Turbine Company | And 2 more authors.
Zhongguo Jixie Gongcheng/China Mechanical Engineering | Year: 2014

The fatigue crack growth properties were important to the welded rotor in nuclear turbine. The fitting relations between the fatigue crack growth rate and stress intensity factor range for submerged arc weld metal of 25Cr2Ni2MoV simulating product of nuclear power low pressure turbine rotors were researched. The critical points between stable and near-threshold fatigue crack propagation were different in different specimens and their locations were determined by the method of backward inference. After the observation of the microstructure around the critical points, a good correspondence between the size of prior austenite and the maximum size of monotonic plastic zone on the crack tip was confirmed. The differences of the critical points between different specimens are caused by the heterogeneous microstructures in the multi-pass and multi-layer weld metal, and become an important reason for the dispersion of the experimental threshold values. ©, 2014, China Mechanical Engineering Magazine Office. All right reserved.

Sun L.,Tsinghua University | Cai Z.,Tsinghua University | Pan J.,Tsinghua University | Liu X.,Shanghai Turbine Company | And 2 more authors.
Zhongguo Jixie Gongcheng/China Mechanical Engineering | Year: 2015

The high cycle fatigue properties for submerged arc welding (SAW) joints and tungsten inert gas (TIG) welding joints of 25Cr2Ni2MoV simulating product of nuclear power low pressure turbine rotors were researched and compared. and the TIG welding joints were found to be better. The interior crack origins of SAW were porosities and inclusions, while these of TIG were porosities. For the conditions of porosities, an approach to evaluate the high cycle fatigue properties was established with the measurement and calculation of characteristic size of crack initiation zones (without crack origins) and crack initiation rate. For the researched welding joints, white-light interfering profilometer was used to measure the characteristic size, and the crack initiation rate of TIG joint is lower, which is in agreement with the experiments. © 2015, China Mechanical Engineering Magazine Office. All right reserved.

Li L.,Xi'an Jiaotong University | Xue T.,Xi'an Jiaotong University | Liu Q.,Xi'an Jiaotong University | Wu X.,Shanghai Turbine Co. | And 2 more authors.
Hsi-An Chiao Tung Ta Hsueh/Journal of Xi'an Jiaotong University | Year: 2014

Aiming at providing guidelines for design of suction slots of hollow stator blade under wet steam flow condition, experiments were implemented on a wet steam test rig with eight hollow stator blades to investigate the water removal performance by varying the position, shape and width of suction slots. The wetness fraction at the inlet section of the test cascade was consistent with the real running condition. It is shown that the amount of removed water is affected by the main flow Mach number and suction pressure difference. When suction pressure difference increases to a moderate value, vaporization of water film occurs and acts as an additional important factor leading to degraded water removal performance. With the position of suction surface slot moving from 0.24 to 0.42 of axial chord, the amount of removed water is continuously increased. Compared with the straight slot, the step-shaped slot cannot improve water removal performance. On the contrary, it results in poor performance when the Mach number is beyond 0.7 due to increased number of sharp corners, which leads to water vaporization. A suction slot with arc-shaped inlet is able to eliminate vaporization of water film and improve water removal performance. A suction slot of 0.35 mm width is apt to allow water film across, a suction slot of 2 mm width cannot form an effective suction pressure difference, and both lead to degraded water removal performance. Suction slots of 0.7 mm and 1 mm width have good water removal performance, but the later is more slightly influenced by water vaporization. ©, 2014, Hsi-An Chiao Tung Ta Hsueh/Journal of Xi'an Jiaotong University. All right reserved.

Long R.-R.,Beijing Institute of Technology | Chen X.,Shanghai Turbine Company | Zhang Q.-M.,Beijing Institute of Technology | Chen L.,Beijing Institute of Technology
Beijing Ligong Daxue Xuebao/Transaction of Beijing Institute of Technology | Year: 2013

The structure characteristic and working principle of the hydro-pneumatic buffer for ship were summarized. Based on the fundamental dynamics knowledge, the mathematics model between shock input and shock output of hydro-pneumatic buffer was established. Through numerical simulation of Matlab, the relation between shock resistance of hydro-pneumatic buffer and influence parameters, such as orifice in compression stroke, orifice in expansion stroke, inner diameter of oil chamber, and the height of the gas chamber was established.

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