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Abstract :
In order to avoid the high cycle fatigue which leads to the failure of turbine blades, friction structural damping has been widely used in turbine blade designs to reduce vibratory stresses by energy dissipation. A method is developed here to analyze the influence of friction structural damping on the vibration characteristics of turbine blades. Vibratory responses of a long steam turbine blade with shroud and snubber are studied. Finite element contact analysis of the steam turbine blades which are modeled in 3-D solid elements is conducted to obtain the normal contact force on the shroud contact surface and snubber contact surface of adjacent blades under five different rotational speeds (2100rpm, 2200rpm, 2413rpm, 2600rpm and 3000rpm). A rig for the tests of non-rotating turbine blade with friction damping structure is built. The normal contact forces of the shroud and snubber are applied to the blade according to numerical results. The response curves and modal damping ratios of the blade under different normal contact forces, which each one is related to a different rotational speed, are obtained. The experimental results show that with increases in rotational speed, modal damping ratio of the blade experiences an increasing period followed by a decreasing period while the resonance amplitude decreases first and then increases when there is only shroud contact. The effects are similar when there are both shroud and snubber contact. The modal damping ratio of the blade is basically identical with that of the uncoupled blade for the rotational speed above 2600rpm. For this range of rotational speed, the resonance frequency increases with the increase of rotational speed, and the changes of the resonance frequency are very trivial.
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GB/T 7714 | Wu, Jun , Xie, Yonghui , Zhang, Di et al. EXPERIMENTAL FRICTION DAMPING CHARACTERISTIC OF A STEAM TURBINE BLADE COUPLED BY SHROUD AND SNUBBER AT STANDSTILL SET-UP [C] . 2012 : 1315-+ . |
MLA | Wu, Jun et al. "EXPERIMENTAL FRICTION DAMPING CHARACTERISTIC OF A STEAM TURBINE BLADE COUPLED BY SHROUD AND SNUBBER AT STANDSTILL SET-UP" . (2012) : 1315-+ . |
APA | Wu, Jun , Xie, Yonghui , Zhang, Di , Zhang, Minghui . EXPERIMENTAL FRICTION DAMPING CHARACTERISTIC OF A STEAM TURBINE BLADE COUPLED BY SHROUD AND SNUBBER AT STANDSTILL SET-UP . (2012) : 1315-+ . |
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Abstract :
Fir-tree root is widely used inblades of gas turbine and large power steam turbine. The structure of root and rim affects the security of the entire blade to a certain extent. Based on the parametric design language APDL, the fir-tree root and rim with complex three-dimensional contact stress, are numerical studied and optimized with multi-variable using the finite element software ANSYS. The zero-order optimization algorithm and the first-order optimization algorithm are combined in the optimization process to enhance the credibility of results. A novel structure of the turbine blade fir-tree root and rim is then obtained. Moreover, numerical results show that equivalent stress has a reduction after the multi-variable optimization when the maximum equivalent stress of root is set as the objective function. Compared with the results of the initial design, the maximum equivalent stress of the root of the optimized design reduces by 4. 56%, and the maximum equivalent stress of the rim reduces by 4. 40%. Relevant results are expected to support the design of turbine blade in theory and then improve the operation reliability of turbo-machinery to some extent.
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GB/T 7714 | Ma, Dandan , Zhang, Di , Xie, Yonghui . Three-dimensional design optimization for fir-tree root of turbine blade with finite element method [C] . 2010 : 998-1001 . |
MLA | Ma, Dandan et al. "Three-dimensional design optimization for fir-tree root of turbine blade with finite element method" . (2010) : 998-1001 . |
APA | Ma, Dandan , Zhang, Di , Xie, Yonghui . Three-dimensional design optimization for fir-tree root of turbine blade with finite element method . (2010) : 998-1001 . |
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Abstract :
Fir-tree root is widely used inblades of gas turbine and large power steam turbine. The structure of root and rim affects the security of the entire blade to a certain extent. Based on the parametric design language APDL, the fir-tree root and rim with complex three-dimensional contact stress, are numerical studied and optimized with multi-variable using the finite element software ANSYS. The zero-order optimization algorithm and the first-order optimization algorithm are combined in the optimization process to enhance the credibility of results. A novel structure of the turbine blade fir-tree root and rim is then obtained. Moreover, numerical results show that equivalent stress has a reduction after the multi-variable optimization when the maximum equivalent stress of root is set as the objective function. Compared with the results of the initial design, the maximum equivalent stress of the root of the optimized design reduces by 4.56%, and the maximum equivalent stress of the rim reduces by 4.40%. Relevant results are expected to support the design of turbine blade in theory and then improve the operation reliability of turbo-machinery to some extent.
Keyword :
design optimization fir-tree root maximum equivalent stress turbine blade
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GB/T 7714 | Ma Dandan , Zhang Di , Xie Yonghui . Three-dimensional Design Optimization for Fir-tree Root of Turbine Blade with Finite Element Method [C] . 2010 : 998-1001 . |
MLA | Ma Dandan et al. "Three-dimensional Design Optimization for Fir-tree Root of Turbine Blade with Finite Element Method" . (2010) : 998-1001 . |
APA | Ma Dandan , Zhang Di , Xie Yonghui . Three-dimensional Design Optimization for Fir-tree Root of Turbine Blade with Finite Element Method . (2010) : 998-1001 . |
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Abstract :
Existing methods for analyzing the stability of a discretized scheme for convection-diffusion terms are usually based on five assumptions, i.e., one-dimensional, linear, first kind of boundary condition, source term free, and uniform grid system. In this article we examine numerically whether deviation from one of the assumptions may enhance the stability of the discretized scheme. The second part of the article is devoted to the criterion of convective boundedness. It is shown that the convective boundedness criterion (CBC) proposed by Gaskell and Lau is only a sufficient condition. Another region in the normalized variable diagram is proposed within which any scheme defined is convectively bounded. Three new bounded high-resolution schemes defined in this region, SBECBC1, 2, and 3, are proposed, and numerical experiments for two advection problems and one diffusion-convection problem demonstrate the high-resolution ability of the SBECBCs for a sharp change in scalar profile.
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GB/T 7714 | Yu, B , Tao, WQ , Zhang, DS et al. Discussion on numerical stability and boundedness of convective discretized scheme [J]. | NUMERICAL HEAT TRANSFER PART B-FUNDAMENTALS , 2001 , 40 (4) : 343-365 . |
MLA | Yu, B et al. "Discussion on numerical stability and boundedness of convective discretized scheme" . | NUMERICAL HEAT TRANSFER PART B-FUNDAMENTALS 40 . 4 (2001) : 343-365 . |
APA | Yu, B , Tao, WQ , Zhang, DS , Wang, QW . Discussion on numerical stability and boundedness of convective discretized scheme . | NUMERICAL HEAT TRANSFER PART B-FUNDAMENTALS , 2001 , 40 (4) , 343-365 . |
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Abstract :
The dynamical behaviors of a flexible rotor supported by two plain cylindrical bearings surrounded by squeeze film damper are investigated. In this study, the Hopf bifurcation theory is used to investigate the stability of the equilibrium position of the system, then the unbalanced rotor response is determined by the shooting method and the stability of these solution is examined using the Floquet transition matrix method. It is shown that the quasi-periodic motion and period-doubling motion may be excited by the rotor unbalance.
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GB/T 7714 | Zhang, JZ , Xu, QY , Zheng, TS . Stability and bifurcation of a rotor-fluid film bearing system with squeeze film damper [J]. | JOURNAL OF VIBRATION AND ACOUSTICS-TRANSACTIONS OF THE ASME , 1998 , 120 (4) : 1003-1006 . |
MLA | Zhang, JZ et al. "Stability and bifurcation of a rotor-fluid film bearing system with squeeze film damper" . | JOURNAL OF VIBRATION AND ACOUSTICS-TRANSACTIONS OF THE ASME 120 . 4 (1998) : 1003-1006 . |
APA | Zhang, JZ , Xu, QY , Zheng, TS . Stability and bifurcation of a rotor-fluid film bearing system with squeeze film damper . | JOURNAL OF VIBRATION AND ACOUSTICS-TRANSACTIONS OF THE ASME , 1998 , 120 (4) , 1003-1006 . |
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Abstract :
An integration formula of enthalpy flow rate along a pulse tube in pulse tube refrigerators is described on the assumption of sinusoidal mass flow rate and sinusoidal pressure fluctuation. For ideal double inlet and ideal orifice pulse tube with helium as working medium, it is simplified to a polynomial formula. Polynomial formulas for roughly evaluating the volume of the pulse tube in ideal double inlet and ideal orifice pulse tube refrigerators are also given. (C) 1999 Elsevier Science Ltd, All rights reserved.
Keyword :
cryocooler pulse tube refrigerator
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GB/T 7714 | Zhu, SW , Chen, ZQ . Enthalpy flow rate of a pulse tube in pulse tube refrigerator [J]. | CRYOGENICS , 1998 , 38 (12) : 1213-1216 . |
MLA | Zhu, SW et al. "Enthalpy flow rate of a pulse tube in pulse tube refrigerator" . | CRYOGENICS 38 . 12 (1998) : 1213-1216 . |
APA | Zhu, SW , Chen, ZQ . Enthalpy flow rate of a pulse tube in pulse tube refrigerator . | CRYOGENICS , 1998 , 38 (12) , 1213-1216 . |
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Abstract :
Theoretical solution for the solidification process around a horizontal tube with internal convection cooling is described in this paper. Boundary layer analysis and the approximate integral method were applied to obtain the solution for the natural convection in the liquid region and the transient temperature profile in the solid region. Effects of Blot number on the wall temperature and the volume fraction solidified are also discussed in this paper.
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GB/T 7714 | Zhang, YW , Chen, ZQ , Faghri, A . Heat transfer during solidification around a horizontal tube with internal convective cooling [J]. | JOURNAL OF SOLAR ENERGY ENGINEERING-TRANSACTIONS OF THE ASME , 1997 , 119 (1) : 44-47 . |
MLA | Zhang, YW et al. "Heat transfer during solidification around a horizontal tube with internal convective cooling" . | JOURNAL OF SOLAR ENERGY ENGINEERING-TRANSACTIONS OF THE ASME 119 . 1 (1997) : 44-47 . |
APA | Zhang, YW , Chen, ZQ , Faghri, A . Heat transfer during solidification around a horizontal tube with internal convective cooling . | JOURNAL OF SOLAR ENERGY ENGINEERING-TRANSACTIONS OF THE ASME , 1997 , 119 (1) , 44-47 . |
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Abstract :
This paper reports the outcome of our research for resolving the very severe disagreement between the computed and measured results of the 90 deg duct how with strong curvature. Three kinds of turbulence models (standard k-epsilon eddy-viscosity turbulence model, RNG k-epsilon model and RNG k-epsilon model with C-mu modification) have been used to predict the above mentioned flow. The results demonstrate that RNG model and the revised model can provide satisfactory computed results. Both of the mean velocities and Reynolds shear stresses are in quantitiative agreement with the experimental data. We feel that the RNG k-epsilon model suggested in this paper can be a useful turbulence model for practical engineering and scientific computations.
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GB/T 7714 | Yin, M , Shi, F , Xu, Z . Renormalization group based kappa-epsilon turbulence model for flows in a duct with strong curvature [J]. | INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE , 1996 , 34 (2) : 243-248 . |
MLA | Yin, M et al. "Renormalization group based kappa-epsilon turbulence model for flows in a duct with strong curvature" . | INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE 34 . 2 (1996) : 243-248 . |
APA | Yin, M , Shi, F , Xu, Z . Renormalization group based kappa-epsilon turbulence model for flows in a duct with strong curvature . | INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE , 1996 , 34 (2) , 243-248 . |
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Abstract :
The coupled heat and mass transfer problem of gas flow over a UHF flat plate with its wall coated with sublimable substance has been solved by local non-similarity method. Considerations have been given also to the effect of non-saturation of the sublimable substance in the oncoming flow and the normal injection velocity at the surface. Analytical results are given for local Nusselt and Sherwood numbers at the various locations.
Keyword :
Heat-mass transfer Laminar flow Uniform heat flux
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GB/T 7714 | Zhang, Yuwen , Chen, Zhongqi , Chen, Mingyong . Local non-similarity solution of coupled heat-mass transfer of a flat plate with uniform heat flux in a laminar parallel flow [J]. | Journal of Thermal Science , 1996 , 5 (2) : 112-116 . |
MLA | Zhang, Yuwen et al. "Local non-similarity solution of coupled heat-mass transfer of a flat plate with uniform heat flux in a laminar parallel flow" . | Journal of Thermal Science 5 . 2 (1996) : 112-116 . |
APA | Zhang, Yuwen , Chen, Zhongqi , Chen, Mingyong . Local non-similarity solution of coupled heat-mass transfer of a flat plate with uniform heat flux in a laminar parallel flow . | Journal of Thermal Science , 1996 , 5 (2) , 112-116 . |
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Abstract :
The dependence of the void growth parameter on the local stress triaxiality and local effective plastic strain near the crack tip of ductile materials provides the motivation to seek for parameters that could rank the ductility of steels. Experimental data for AS 1405-180, AS 1204-350, HY-80 and C-Mn steels show that the crack tip opening displacement (CTOD) at initiation delta(c), decreases with increasing crack tip stress triaxiality. This trend is confirmed by analysis. As the critical local effective plastic strain epsilon(ec) also decreases with increasing local stress triaxiality, the ratio delta(c)/epsilon(ec) is found to remain nearly constant or independent of the local constraint, i.e., the stress triaxiality. These parameters are given for a class of steels in this paper. Their association with the resistance to ductile fracture remains to be investigated.
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GB/T 7714 | WANG, TJ , LI, DJ , MA, FS et al. INFLUENCE OF STRESS TRIAXIALITY ON DAMAGE AND CRACK-TIP OPENING DISPLACEMENT PARAMETERS FOR STEELS [J]. | THEORETICAL AND APPLIED FRACTURE MECHANICS , 1995 , 22 (2) : 151-158 . |
MLA | WANG, TJ et al. "INFLUENCE OF STRESS TRIAXIALITY ON DAMAGE AND CRACK-TIP OPENING DISPLACEMENT PARAMETERS FOR STEELS" . | THEORETICAL AND APPLIED FRACTURE MECHANICS 22 . 2 (1995) : 151-158 . |
APA | WANG, TJ , LI, DJ , MA, FS , KUANG, ZB . INFLUENCE OF STRESS TRIAXIALITY ON DAMAGE AND CRACK-TIP OPENING DISPLACEMENT PARAMETERS FOR STEELS . | THEORETICAL AND APPLIED FRACTURE MECHANICS , 1995 , 22 (2) , 151-158 . |
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