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  • ASME International  (9)
  • 1
    Online Resource
    Online Resource
    Endwall Film Cooling Performance for a First-Stage Guide Vane With Upstream Combustor Walls and Inlet Injection
    ASME International ; 2019
    In:  Journal of Thermal Science and Engineering Applications Vol. 11, No. 1 ( 2019-02-01)
    Details
    In: Journal of Thermal Science and Engineering Applications, ASME International, Vol. 11, No. 1 ( 2019-02-01)
    Abstract: Effects of an upstream combustor wall on turbine nozzle endwall film cooling performance are numerically examined in a linear cascade in this paper. Film cooling is by two rows of cooling holes at 20% of the axial chord length upstream of the vane leading edge (LE) plane. The combustor walls are modeled as flat plates with square trailing edges (TE) positioned upstream of the endwall film cooling holes. A combustor wall is in line with the LE of every second vane. The influence of the combustor wall, when shifted in the axial and tangential directions, is investigated to determine effects on passage endwall cooling for three representative film cooling blowing ratios. The results show how shed vortices from the combustor wall greatly alter the flow field near the cooling holes and inside the vane passage. Film cooling distribution patterns, particularly in the entry region and along the pressure side of the passage, are affected. The combustor wall leads to an imbalance in film cooling distribution over the endwalls for adjacent vane passages. Results show a larger effect of tangential shift of the combustor wall on endwall cooling effectiveness than the effect of an equal axial shift. The study provides guidance regarding design of combustor-to-turbine transition ducts.
    Type of Medium: Online Resource
    ISSN: 1948-5085 , 1948-5093
    URL: Article
    DOI: 10.1115/1.4041342
    Language: English
    Publisher: ASME International
    Publication Date: 2019
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  • 2
    Online Resource
    Online Resource
    Comparisons of Endwall Overall Effectiveness From Two Film Hole Distribution Patterns at Low and High Exit Mach Numbers
    ASME International ; 2020
    In:  Journal of Turbomachinery Vol. 142, No. 10 ( 2020-10-01)
    Details
    In: Journal of Turbomachinery, ASME International, Vol. 142, No. 10 ( 2020-10-01)
    Abstract: In this paper, detailed overall cooling effectiveness and associated flow patterns are presented for two distinct film hole distribution patterns over a turbine endwall: an axial-row pattern and an iso-Mach number line row pattern. Measurements, in combination with numerical simulations, are performed in a scaled-up cascade. Thermal protection for the endwall is achieved by jet-array impingement on the cold side and discrete film cooling on the hot-gas side, combined with purge air from an inclined slot that simulates the upstream seal cavity. Infrared (IR) thermography techniques are used to obtain overall effectiveness in a wide range of coolant flow ratios of 1.5–3.8%. Mach numbers at the exit of the vane cascade are 0.25 and 0.70, representing the variations of engine operating conditions. Overall effectiveness measurements and computational flowfields show that the iso-Mach number line hole pattern outperforms the hole pattern with axial rows of holes in terms of overall effectiveness levels and thermodynamic energy losses, regardless of coolant flow ratios. Increasing Mach number increases overall effectiveness levels on the endwall and higher Mach numbers generate higher effectiveness improvement for the iso-Mach number line arrangement, relative to the axial-row configuration. Additionally, adding purge air to the endwall considerably improves the overall effectiveness levels and purge air performs better for the axial-row pattern due to no direct interactions with downstream discrete coolant injection.
    Type of Medium: Online Resource
    ISSN: 0889-504X , 1528-8900
    URL: Article
    DOI: 10.1115/1.4047809
    Language: English
    Publisher: ASME International
    Publication Date: 2020
    detail.hit.zdb_id: 56356-0
    detail.hit.zdb_id: 2010462-5
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    Online Resource
  • 3
    Online Resource
    Online Resource
    Experimental Study on Fault Caused by Partial Arc Steam Forces and Its Economic Solution
    ASME International ; 2010
    In:  Journal of Engineering for Gas Turbines and Power Vol. 132, No. 6 ( 2010-06-01)
    Details
    In: Journal of Engineering for Gas Turbines and Power, ASME International, Vol. 132, No. 6 ( 2010-06-01)
    Abstract: It is noticed in a few steam turbines that there are a pad temperature rise of more than 10°C and a radial journal movement of more than 50 μm in the bearings adjacent to control stage when they operate under partial arc admission at 60–80% of their full load. It is found through fault mechanism analysis and experimental study that the fault is caused by partial arc steam forces acting on control stage. A fault characteristic is concluded to help identify this fault. Diagonal admission is therefore proposed as an economic solution for elimination of this fault and it is proved to be effective through practical test.
    Type of Medium: Online Resource
    ISSN: 0742-4795 , 1528-8919
    URL: Article
    DOI: 10.1115/1.4000090
    Language: English
    Publisher: ASME International
    Publication Date: 2010
    detail.hit.zdb_id: 2010437-6
    detail.hit.zdb_id: 165371-4
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  • 4
    Online Resource
    Online Resource
    Establishment of Nonlinear Dynamic Model for Prediction of Rotordynamic Instability of Steam Turbine Rotor-Bearing System Caused by Partial Admission
    ASME International ; 2012
    In:  Journal of Engineering for Gas Turbines and Power Vol. 134, No. 7 ( 2012-07-01)
    Details
    In: Journal of Engineering for Gas Turbines and Power, ASME International, Vol. 134, No. 7 ( 2012-07-01)
    Abstract: A nonlinear dynamic model is developed for a rotor-bearing system with radial steam force due to partial admission, taking into account the prediction of subsynchronous instability of a steam turbine. The optimum schemes are obtained by comparing the rotor responses subjected to maximal radial steam forces in different partial admission schemes. It is found through comparison that the instability of a rotor-bearing system is directly related to the direction of the radial steam force in the partial admission scheme.
    Type of Medium: Online Resource
    ISSN: 0742-4795 , 1528-8919
    URL: Article
    DOI: 10.1115/1.4006078
    Language: English
    Publisher: ASME International
    Publication Date: 2012
    detail.hit.zdb_id: 2010437-6
    detail.hit.zdb_id: 165371-4
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  • 5
    Online Resource
    Online Resource
    A Numerical Study on the Effect of Bleed System on Starting Ability and Flow Performance of Rampressor Inlet
    ASME International ; 2014
    In:  Journal of Engineering for Gas Turbines and Power Vol. 136, No. 12 ( 2014-12-01)
    Details
    In: Journal of Engineering for Gas Turbines and Power, ASME International, Vol. 136, No. 12 ( 2014-12-01)
    Abstract: A unique supersonic compressor rotor with high pressure ratio, termed the Rampressor, is presented by Ramgen Power Systems, Inc., (RPS). Based on the models of Rampressor inlet, the inlet flow field with bleed system is numerically studied. Validation of the employed computational fluid dynamics (CFD) scheme is provided through test cases. The effects of boundary layer bleed location and bleed amount on Rampressor rotor inlet start and flow performance are analyzed. The results indicate that the boundary layer bleed has a significant effect for start and flow performance of Rampressor inlet. Boundary layer bleed technique has been applied to eliminate the emerging flow separation zone for enhancing Rampressor rotor inlet performance and enlarging its stable working range. The starting ability and flow performance of Rampressor inlet are efficiently improved by bleeding system, but the improvement effect is different for Rampressor inlet with different bleed location. Along the position of bleeding system moves forward, the range of Rampressor inlet normal work rotation speed is enlarged. The flow performance of Rampressor inlet improves obviously with the increment of bleed flow rate, and exit stability of Rampressor inlet enhances. And in the same back pressure work condition of Rampressor inlet, bleed system has been shown to be effective that exit stability of Rampressor inlet ameliorates, but the loss of compressed air from the bleed system has a negative effect on overall Rampressor inlet efficiency.
    Type of Medium: Online Resource
    ISSN: 0742-4795 , 1528-8919
    URL: Article
    DOI: 10.1115/1.4027761
    Language: English
    Publisher: ASME International
    Publication Date: 2014
    detail.hit.zdb_id: 2010437-6
    detail.hit.zdb_id: 165371-4
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  • 6
    Online Resource
    Online Resource
    Nonlinear Dynamic Analysis of an Unsymmetrical Generator-Bearing System
    ASME International ; 2007
    In:  Journal of Vibration and Acoustics Vol. 129, No. 4 ( 2007-08-01), p. 448-457
    Details
    In: Journal of Vibration and Acoustics, ASME International, Vol. 129, No. 4 ( 2007-08-01), p. 448-457
    Abstract: Considering both nonlinear oil film force and unsymmetrical stiffness, this paper presents a mechanical model of a generator-bearing system. The complex mode synthesis method is used to reduce the linear degrees of freedom of the high order model in the rotating coordinates, and one-order modal differential equations are obtained which may not be solved directly by Newmark-β method. To solve this problem, a modified Newmark-β method is presented to investigate dynamic effects of the asymmetry of rotor stiffness, the viscosity of oil, the rotor unbalance and the ratio of length to diameter of bearings. Three-dimension diagrams and unfiltered vibration curves are used as tools to examine the dynamic behavior of the system, and some insights into the dynamic behavior are given. Numerical results show that instability of the system may be improved by modifying these parameters.
    Type of Medium: Online Resource
    ISSN: 1048-9002 , 1528-8927
    URL: Article
    DOI: 10.1115/1.2731407
    Language: English
    Publisher: ASME International
    Publication Date: 2007
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  • 7
    Online Resource
    Online Resource
    Performance Analysis of Oil Lubricated Foil Bearing With Flexible Supported Back Spring Structure—Part I: Model Development and Numerical Investigation
    ASME International ; 2014
    In:  Journal of Engineering for Gas Turbines and Power Vol. 136, No. 11 ( 2014-11-01)
    Details
    In: Journal of Engineering for Gas Turbines and Power, ASME International, Vol. 136, No. 11 ( 2014-11-01)
    Abstract: A new type of multileaf oil lubricated foil bearing with flexible supported back spring structure was proposed to satisfy the requirement of high rotating velocity for turbo pump, where the rotor was submerged in the hydraulic oil. The numerical analysis was carried out in this paper. Based on the structure of oil foil bearing, the film thickness model was established without foil deformation. By employing Castigliano's theorem, the total flexibility matrix including the elastic back spring and cantilevered curved beam was calculated, and then compared with commercial finite element software to verify the accuracy of the proposed model. The obtained flexibility matrix was brought into the static and dynamic oil lubricated Reynolds equation. The Reynolds boundary condition was considered to simulate the oil film rupture effect. The deformation equation for the structure and the Reynolds equation were solved coupled by the successive over relaxation method. The static and dynamic characteristics of the oil lubricated multileaf foil bearing with supported back spring were acquired. The effect of the foil thickness on the load capacity was discussed. The variation of the dynamic coefficients with bearing load was acquired. By employing Routh–Hurwitz method, the stability of the bearing was analyzed. The results indicated that the load capacity of the foil bearing with back supported spring was bigger than that of the foil bearing without back supported spring. The stability characteristics of the foil bearing with back supported structure was better than traditional rigid self-acting bearing, particular for the high rotating speed case.
    Type of Medium: Online Resource
    ISSN: 0742-4795 , 1528-8919
    URL: Article
    DOI: 10.1115/1.4027602
    Language: English
    Publisher: ASME International
    Publication Date: 2014
    detail.hit.zdb_id: 2010437-6
    detail.hit.zdb_id: 165371-4
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  • 8
    Online Resource
    Online Resource
    Nonlinear Dynamic of a Geared Rotor System With Nonlinear Oil Film Force and Nonlinear Mesh Force
    ASME International ; 2012
    In:  Journal of Vibration and Acoustics Vol. 134, No. 4 ( 2012-08-01)
    Details
    In: Journal of Vibration and Acoustics, ASME International, Vol. 134, No. 4 ( 2012-08-01)
    Abstract: To investigate the effect of oil film force on a geared rotor system, a short journal bearing model was applied to represent nonlinear oil film force. A dynamic model of the geared rotor oil journal bearing system was presented. The nonlinear gear mesh force and nonlinear oil film force were considered in the model. The nonlinear dynamic responses of the system were investigated by numerical integration method. This article shows that when the rotational speed is relatively low, the vibration of the system is mainly affected by nonlinear mesh force. With the increase of rotational speed, the influence of nonlinear oil film force also increases gradually, and the subsynchronous forward precession phenomena appear. When the speed increases to a certain value, the amplitude of the subsynchronous forward precession exceeds the amplitude of the rotational frequency, and the nonlinear mesh force is greatly affected by the nonlinear oil film force. However, the linear oil film force does not affect the nonlinear mesh force. The subsynchronous forward precession is difficult to be predicted by linear oil film force which was previously applied. This experiment is performed to validate the correctness of the dynamic model presented, and the numerical integration results of low speeds are validated by the experimental data.
    Type of Medium: Online Resource
    ISSN: 1048-9002 , 1528-8927
    URL: Article
    DOI: 10.1115/1.4005032
    Language: English
    Publisher: ASME International
    Publication Date: 2012
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  • 9
    Online Resource
    Online Resource
    Performance Analysis of Oil Lubricated Foil Bearing With Flexible Supported Back Spring Structure—Part II: Comparison of Predictions and Measured Test Data
    ASME International ; 2014
    In:  Journal of Engineering for Gas Turbines and Power Vol. 136, No. 11 ( 2014-11-01)
    Details
    In: Journal of Engineering for Gas Turbines and Power, ASME International, Vol. 136, No. 11 ( 2014-11-01)
    Abstract: As described in Part I (Zhang et al., “Performance Analysis of Oil Lubricated Foil Bearing With Flexible Supported Back Spring Structure—Part I: Model Development and Numerical Investigation”, ASME J. Eng. Gas Turbines Power, 136(11), p. 112501), a new type of multileaf oil lubricated foil bearing with flexible supported back spring structure was proposed and the characteristics were obtained by theoretical analysis and numerical simulation. Until now, nearly no paper about the modeling method and experimental verification for this type foil bearing published. So it is necessary to study the performance of this kind bearing by experiments. The experimental rig for the static and dynamic characteristics of the bearing was installed and the experiments were carried out. The stiffness of the back supported spring was measured. By employing the dynamic coefficients identification algorithm for oil foil bearing, the data acquisition delay was compensated. The load capacity, stiffness coefficients and damping coefficients were obtained. The load capacity resulting from the experiment was coincided with the theoretical simulation well. The stiffness and damping coefficients from the experiments had the similar tendency with those from the theoretical analysis. The stiffness coefficients obtained from experiments were coincided well with the numerical simulation results, and the difference of damping coefficients was a little bigger.
    Type of Medium: Online Resource
    ISSN: 0742-4795 , 1528-8919
    URL: Article
    DOI: 10.1115/1.4027603
    Language: English
    Publisher: ASME International
    Publication Date: 2014
    detail.hit.zdb_id: 2010437-6
    detail.hit.zdb_id: 165371-4
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