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Shanghai, China

Chi Z.,Shanghai JiaoTong University | Liu H.,CAS Shanghai Advanced Research Institute | Zang S.,Shanghai JiaoTong University | Jiao G.,Shanghai Turbine Works Co.
Proceedings of the ASME Turbo Expo

This paper discusses the methodology of impingement cooling optimization of a gas turbine 2nd stage vane with 3D conjugate heat transfer (CHT) CFD analysis applied. The vane is installed with a novel impingement cooling structure in the leading cavity and a pin-fin array in the trailing edge. This study involves the optimization of the impingement cooling structure, including the location of the jet holes and the diameter of each hole. The generation of 3D model and CHT mesh was realized using an in-house code developed specifically for turbine cooling optimization. A constant pressure drop was assumed within the cooling system during optimization. To make the optimization computationally faster, a metamodel which can predict the detailed distribution of metal temperature on the vane surface was used in the second-level search together with a genetic algorithm. An optimal nonuniform impingement cooling structure in the leading cavity was automatically designed by the optimization process costing only dozens of CFD runs, which provided a more uniform temperature distribution on the vane surface and required no more coolant amount compared with the initial impingement cooling structure. © Copyright 2015 by ASME. Source

Liu L.,Shanghai JiaoTong University | Zhou D.,Shanghai Turbine Works Co. | Liu H.,Shanghai JiaoTong University | Zhu X.,Shanghai JiaoTong University | Du Z.,Shanghai JiaoTong University
Proceedings of the ASME Turbo Expo

The cooling protection of the hot end is the key technique for ultra-supercritical steam turbine to cool the hot components. In this paper, the internal flow mechanism and cooling characteristics in the tangential direction cooling channel in the intermediate pressure cylinder (IPC) are investigated using the method of computational fluid dynamics. Various turbulence models and mesh sizes are evaluated (the k-ε model, the k-ω model, the SST model). Also, calculated results of the nonrotating bottom wall are compared with the experimental results in a previous research to show the reliability of the CFD program used. Detailed predictions of the contours of velocity, pressure and temperature are carried out. The focus of this study is to investigate the effects of inlet Mach number, turbulent Prandtl number, rotational wall speed, and inlet turbulence intensity on the cooling effectiveness of the vortex channel. The inlet Mach number, the turbulent Prandtl number, the rotational wall speed and the inlet turbulence intensity varied from 0.315 to 0.512, from 0.71 to 1.0, from 0 to 3000rpm, and from 1% to 10%, respectively. Results show that the parameters have different effects on the cooling effectiveness of the vortex cooling chamber. The cooling effect of the vortex channel increases with increasing inlet Mach number and rotational wall speed, while decreases with the increasing turbulent Prandtl number. As the inlet turbulence intensity increases, the cooling effect increases firstly, and then decreases. Copyright © 2015 by ASME. Source

Guo Q.,Shanghai JiaoTong University | Lu F.,Shanghai JiaoTong University | Cui H.,Shanghai JiaoTong University | Yang R.,Shanghai Turbine Works Co. | And 2 more authors.
Journal of Materials Processing Technology

Crack propagation behavior in different zones of advanced 9Cr/CrMoV dissimilar steel welded joint was simulated by ABAQUS software. The Gurson-Tvergaard-Needleman (GTN) damage model and brittle cracking model were introduced to analyze the crack propagation behavior for ductile and brittle region on the dissimilar steel welded joint, respectively. It is found that the numerically calculated J-Δa resistance curves for the ductile regions i.e., the CrMoV base metal (CrMoV-BM), the heat affected zone of CrMoV (CrMoV-HAZ) and weld metal (WM) matched the experimental results, implying the reliability of the model developed in the present study. Three cases with different initial crack length (a0) were simulated to probe into the effect of a0 on the crack propagation resistance. The simulated results revealed that higher equivalent plastic strain and stress triaxiality occurred on the right ahead of the crack tip for longer initial crack length, which induces the lower crack propagation resistance. The brittle crack propagation behavior in 9Cr base metal (9Cr-BM) and heat affected zone of 9Cr (9Cr-HAZ) was well simulated by the brittle cracking model. The local stress distribution around the crack tip before crack destabilization could be obtained from the established model for BM and HAZ of 9Cr steel. © 2015 Elsevier B.V. All rights reserved. Source

Liu W.,Shanghai JiaoTong University | Lu F.,Shanghai JiaoTong University | Yang R.,Shanghai Turbine Works Co. | Tang X.,Shanghai JiaoTong University | Cui H.,Shanghai JiaoTong University
Journal of Materials Processing Technology

Five kinds of thermal cycle, with different peak temperatures ranging between 1150 °C and 1350 °C were taken to simulate HAZs with same heating and cooling rate. The microstructure of different simulated HAZs was characterized by optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM). The micro-hardness, grain size and tensile test at 750 °C of simulated HAZs were conducted. Coarsened carbides along the grain boundaries are observed in the HAZs simulated at 1200 °C and 1250 °C. For the HAZs simulated at 1300 °C and 1350 °C, the carbides inside grains vanish, and continuous lamellar structure occurs at the grain boundaries. The microstructure of HAZ simulated at 1150 °C is similar to that of base metal (BM). The micro-hardness and average grain size of simulated HAZs have no obvious variation compared to the BM. Tensile test results show that the yield stress (YS) and ultimate tensile stress (UTS) decrease as simulation peak temperature increases, which attributes to the coarsened carbides and continuous lamellar structure occurring at the grain boundaries at higher temperature. © 2015 Elsevier B.V. All rights reserved. Source

Ren W.,Shanghai JiaoTong University | Lu F.,Shanghai JiaoTong University | Yang R.,Shanghai Turbine Works Co. | Liu X.,Shanghai Turbine Plant of Shanghai Electrical Power Generation Equipment Co. | And 2 more authors.
Materials and Design

A comparative study on the influence of fiber laser welding (FLW) and CO2 laser welding (CLW) on the weld bead geometry and the microstructure of fusion zone (FZ) of Inconel 617 was investigated. In CLW joints, the weld bead geometry is Y-type shape. In FLW joints, the weld bead geometry transforms from Y-type to I-type with the decrease of the heat input. The minimum heat input required to achieve the full penetration of the weldment in FLW is lower than the CLW. The melting efficiency in FLW is higher than that in CLW. From the top to the root regions, the secondary dendrite arm spacing (SDAS) in fiber laser welded FZ undergoes a smaller change than that in CO2 laser welded FZ. The elements of Ti, Mo, Cr and Co segregate into the interdendritic regions both in FLW and CLW process. The second phases in CLW with the highest input of 360J/mm are much larger and more than ones in FLW with the highest heat input of 210.5J/mm. © 2015 Elsevier Ltd. Source

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