The Experts below are selected from a list of 17796 Experts worldwide ranked by ideXlab platform
E. Galloni - One of the best experts on this subject based on the ideXlab platform.
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Influence of the snubber on temperature distribution at last stage Blade exit of a steam turbine during low volume flow operations
Applied Thermal Engineering, 2019Co-Authors: Antonio Mambro, Francesco Congiu, E. GalloniAbstract:Abstract Flow field and temperature distribution at last stage moving Blades outlet for freestanding and snubber Blades have been investigated experimentally and numerically. The same airfoil geometry of a steam turbine last stage Blades, with and without snubber, has been tested in a four-stage scaled steam turbine and computed using ANSYS CFX 16.0. Initially, measurements comparison of the main flow quantities such as velocity components, pressure and temperature distribution at the exit of the last stage Blades is carried out. Afterwards, the CFD results are validated against measurements. Finally, a detailed discussion of the flow field of the two geometries and its influence on maximum temperature is presented. The local cooling effect at the Blade tip experienced by snubber Blades enables a further reduction of the sprayed water during low volume flow operations with a consequent reduction in trailing edge erosion. Snubber Blades, for a given maximum flow tip temperature, can run at even reduced volumetric flow compared to equivalent freestanding Blades. The capability of assessing the maximum temperature achieved by the last stage moving Blades (LSMB) along with the influence of the coupling elements usually required to stiff long last stage Blades, is a key aspect for the optimization of the power plant design for low volume flow operations and lifetime improvement. Furthermore, the flow physics of the freestanding and snubber last stage moving Blades during low volume flow (LVF) operations is presented.
Danmei Xie - One of the best experts on this subject based on the ideXlab platform.
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The Effect of Suction Side Tubercles on Torque Output of a Steam Turbine Low-Pressure Last Stage Blade
Energies, 2020Co-Authors: Jing Zhang, Chun Wang, Ziyue Mei, An Han, Danmei XieAbstract:Flow separation and different kinds of stall flows occur under low load conditions for steam turbine last stage Blades. In order to delay the flow separation and increase turbine power production, we applied suction side tubercles on steam turbine low-pressure last stage Blades in the present study. The amplitude, wavelength, position, and thickness were considered as our design variables. We used the orthogonal test method (OTM) to generate modified Blades with different tubercle variables that were then numerically simulated by a three-dimensional computational fluid dynamics (CFD) analysis. The Blade axial torque of the nine modified tests was compared with the original Blade. The results showed that the application of bionic tubercles on the suction side of the steam turbine Blade is a promising solution to improve the Blade axial torque for all modified tests with a maximum increase of 33.32% due to the turbulent vortices generated by bionic tubercles.
Simon Hogg - One of the best experts on this subject based on the ideXlab platform.
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A novel method of coupling the steam turbine exhaust hood and the last stage Blades using the non-linear harmonic method.
Volume 5B: Oil and Gas Applications; Steam Turbines, 2013Co-Authors: Zoe Burton, Grant Ingram, Simon HoggAbstract:The exhaust hood of a steam turbine is a vital area of turbomachinery research its performance strongly influences the power output of the last stage Blades. It is well known that accurate CFD simulations are only achieved when the last stage Blades are coupled to the exhaust hood to capture the strong interaction. This however presents challenges as the calculation size grows rapidly when the full annulus is calculated. The size of the simulation means researchers are constantly searching of methods to reduce the computational effort without compromising solution accuracy.This work uses a novel approach, by coupling the last stage Blades and exhaust hood by the Non-Linear Harmonic Method, a technique widely used to reduce calculation size in high pressure turbine Blades and axial compressors. This has been benchmarked against the widely adopted Mixing Plane method. The test case used is the Generic Geometry, a representative exhaust hood and last stage Blade geometry that is free from confidentiality and IP restrictions and for which first calculations were presented at last year’s conference [1]. The results show that the non-uniform exhaust hood inlet flow can be captured using the non-liner harmonic method, an effect not previously achievable with single passage coupled calculations such as the mixing plane approach. This offers a significant computational saving, estimated to be a quarter of the computation time compared with alternative methods of capturing the asymmetry with full annulus frozen rotor calculations.Copyright © 2013 by ASME
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a generic steam turbine exhaust diffuser with tip leakage modelling and non uniform hood outlet
The 10th European Conference on Turbomachinery Fluid Dynamics and Thermodynamics ETC 10 Lappeenranta Finland 15-19 April 2013 [Conference proceedings], 2013Co-Authors: Zoe Burton, Grant Ingram, Simon HoggAbstract:This paper advances the work of Burton et al. (2012) to highlight the significance of the last stage Blade tip leakage jet on the flow structure in the low pressure (LP) steam turbine exhaust hood, widely regarded as being significant in other published research. The flow structure in the exhaust hood is distinctly asymmetric when the leakage jet is included due to the increased swirl. This paper offers the new contribution of the effect of the condenser on the flow structure within the exhaust hood. It has been shown that the pressure gradient at the condenser inlet due to the heating of the cooling water reduces the asymmetry caused by the tip leakage jet. Improvements have been made to Durham University’s public domain LP exhaust diffuser with accompanying last stage Blades geometry to include the flare of the casing.
Antonio Mambro - One of the best experts on this subject based on the ideXlab platform.
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Influence of the snubber on temperature distribution at last stage Blade exit of a steam turbine during low volume flow operations
Applied Thermal Engineering, 2019Co-Authors: Antonio Mambro, Francesco Congiu, E. GalloniAbstract:Abstract Flow field and temperature distribution at last stage moving Blades outlet for freestanding and snubber Blades have been investigated experimentally and numerically. The same airfoil geometry of a steam turbine last stage Blades, with and without snubber, has been tested in a four-stage scaled steam turbine and computed using ANSYS CFX 16.0. Initially, measurements comparison of the main flow quantities such as velocity components, pressure and temperature distribution at the exit of the last stage Blades is carried out. Afterwards, the CFD results are validated against measurements. Finally, a detailed discussion of the flow field of the two geometries and its influence on maximum temperature is presented. The local cooling effect at the Blade tip experienced by snubber Blades enables a further reduction of the sprayed water during low volume flow operations with a consequent reduction in trailing edge erosion. Snubber Blades, for a given maximum flow tip temperature, can run at even reduced volumetric flow compared to equivalent freestanding Blades. The capability of assessing the maximum temperature achieved by the last stage moving Blades (LSMB) along with the influence of the coupling elements usually required to stiff long last stage Blades, is a key aspect for the optimization of the power plant design for low volume flow operations and lifetime improvement. Furthermore, the flow physics of the freestanding and snubber last stage moving Blades during low volume flow (LVF) operations is presented.
Jing Zhang - One of the best experts on this subject based on the ideXlab platform.
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The Effect of Suction Side Tubercles on Torque Output of a Steam Turbine Low-Pressure Last Stage Blade
Energies, 2020Co-Authors: Jing Zhang, Chun Wang, Ziyue Mei, An Han, Danmei XieAbstract:Flow separation and different kinds of stall flows occur under low load conditions for steam turbine last stage Blades. In order to delay the flow separation and increase turbine power production, we applied suction side tubercles on steam turbine low-pressure last stage Blades in the present study. The amplitude, wavelength, position, and thickness were considered as our design variables. We used the orthogonal test method (OTM) to generate modified Blades with different tubercle variables that were then numerically simulated by a three-dimensional computational fluid dynamics (CFD) analysis. The Blade axial torque of the nine modified tests was compared with the original Blade. The results showed that the application of bionic tubercles on the suction side of the steam turbine Blade is a promising solution to improve the Blade axial torque for all modified tests with a maximum increase of 33.32% due to the turbulent vortices generated by bionic tubercles.
