Nonequilibrium Throughflow Analyses of Low-Pressure, Wet Steam Turbines

1984 ◽  
Vol 106 (4) ◽  
pp. 716-724 ◽  
Author(s):  
C. C. Yeoh ◽  
J. B. Young
Keyword(s):  
Low Pressure ◽  
Computational Method ◽  
Virial Equation ◽  
Complete Analysis ◽  
Steam Turbines ◽  
Wet Steam ◽  
Streamline Curvature ◽  
Low Pressure Turbine ◽  
Aerodynamic Parameters ◽  
Theoretical Test

The paper describes a throughflow computational method that combines wet steam theory with an axisymmetric streamline curvature technique in order to predict nonequilibrium effects in low-pressure steam turbines. The computer program developed is able to deal with both subsonic and fully choked supersonic flows, and steam properties are represented by a truncated virial equation of state. A number of theoretical test cases have been investigated, including the nonequilibrium flow in the primary nucleating stage of a low-pressure turbine and the complete analysis of a six-stage, 320-MW operational turbine. The calculations are the first of their kind in being able to provide information on the spanwise variation of the Wilson point, the average droplet size nucleated, the degree of supercooling throughout the flowfield, the thermodynamic wetness loss, and the nonequilibrium choking mass flow rate in addition to the aerodynamic parameters which are of interest to the designer.

Unsteady Wet-Steam Flows Through Low Pressure Turbine Final Three Stages Considering Blade Number

2015 ◽  
Author(s):  
Satoshi Miyake ◽  
Hironori Miyazawa ◽  
Satoru Yamamoto ◽  
Yasuhiro Sasao ◽  
Kazuhiro Momma ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Low Pressure ◽  
Numerical Results ◽  
Steam Turbines ◽  
Wet Steam ◽  
Flow Simulations ◽  
Low Pressure Turbine ◽  
Blade Number ◽  
Pressure Steam ◽  
Three Stages

Unsteady three-dimensional wet-steam flows through stator–rotor blade rows in the final three stages of a low-pressure steam turbine, taking the blade number into consideration, are numerically investigated. In ASME Turbo Expo 2014, we presented the numerical results of the unsteady flow assuming the same blade number. Here, this previous study is extended to flow simulations using the real blade number. The flows under three flow conditions, with and without condensation and considering the same and real blade numbers are simulated, and the numerical results are compared with each other and with the experimental results. Finally, the effect of the blade number on unsteady wet-steam flows in real low-pressure steam turbines is discussed.

Sequential vs Multidisciplinary Coupled Optimization and Efficient Surrogate Modelling of a Last Stage and the Successive Axial Radial Diffuser in a Low Pressure Steam Turbine

2014 ◽  
Author(s):  
Kevin Cremanns ◽  
Dirk Roos ◽  
Arne Graßmann
Keyword(s):  
Steam Turbine ◽  
Design Process ◽  
Energy Demand ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Low Pressure ◽  
Steam Turbines ◽  
Low Pressure Turbine ◽  
Pressure Steam ◽  
Last Stage

In order to meet the requirements of rising energy demand, one goal in the design process of modern steam turbines is to achieve high efficiencies. A major gain in efficiency is expected from the optimization of the last stage and the subsequent diffuser of a low pressure turbine (LP). The aim of such optimization is to minimize the losses due to separations or inefficient blade or diffuser design. In the usual design process, as is state of the art in the industry, the last stage of the LP and the diffuser is designed and optimized sequentially. The potential physical coupling effects are not considered. Therefore the aim of this paper is to perform both a sequential and coupled optimization of a low pressure steam turbine followed by an axial radial diffuser and subsequently to compare results. In addition to the flow simulation, mechanical and modal analysis is also carried out in order to satisfy the constraints regarding the natural frequencies and stresses. This permits the use of a meta-model, which allows very time efficient three dimensional (3D) calculations to account for all flow field effects.

Numerical Investigation of Three-Dimensional Wet Steam Flows in an Exhaust Diffuser With Non-Uniform Inlet Flows From the Turbine Stages in a Steam Turbine

2012 ◽  
Author(s):  
Tadashi Tanuma ◽  
Yasuhiro Sasao ◽  
Satoru Yamamoto ◽  
Yoshiki Niizeki ◽  
Naoki Shibukawa ◽  
...  
Keyword(s):  
Steam Turbine ◽  
Numerical Investigation ◽  
Evaluation Method ◽  
High Efficiency ◽  
Mechanical Design ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Steam Turbines ◽  
Wet Steam ◽  
Low Pressure Turbine

The purpose of this paper is to present a numerical evaluation method for the aerodynamic design and development of high-efficiency exhaust diffusers in steam turbines, as well as to present the comparison between the numerical results and measured data in an actual real scale development steam turbine. This paper presents numerical investigation of three-dimensional wet steam flows in a down-flow-type exhaust diffuser that has non-uniform inlet flows from a typical last turbine stage. This stage has long transonic blades designed using recent aerodynamic and mechanical design technologies, including superimposed leakages and blade wakes from several upstream low pressure turbine stages. The present numerical flow analysis showed detail three-dimensional flow structures considering circumferential flow distributions caused by the down-flow exhaust hood geometry and the swirl velocity component from the last stage blades, including flow separations in the exhaust diffuser. The results were compared with experimental data measured in an actual development steam turbine. Consequently, the proposed aerodynamic evaluation method was proved to be sufficiently accurate for steam turbine exhaust diffuser aerodynamic designs.

scholarly journals New two-tier low pressure turbine for heavy duty steam turbines

2017 ◽  
Vol 891 ◽  
pp. 012257 ◽  
Author(s):  
A E Zaryankin ◽  
A N Rogalev ◽  
S K Osipov ◽  
N M Bychkov
Keyword(s):  
Low Pressure ◽  
Steam Turbines ◽  
Heavy Duty ◽  
Low Pressure Turbine

Nonequilibrium Streamline Curvature Throughflow Calculations in Wet Steam Turbines

1982 ◽  
Vol 104 (2) ◽  
pp. 489-496 ◽  
Author(s):  
C. C. Yeoh ◽  
J. B. Young
Keyword(s):  
High Pressure ◽  
Computer Program ◽  
Calculation Method ◽  
Stage Model ◽  
Steam Turbines ◽  
Wet Steam ◽  
Equilibrium Solutions ◽  
High Pressure Turbine ◽  
One Dimensional ◽  
Streamline Curvature

The paper describes a computer program which combines the streamline curvature throughflow calculation method with one-dimensional wet steam theory. Two subsonic applications are described in detail: (i) the nucleating flow in a convergent-straight annular duct and (ii) the flow in a 14-stage model high pressure turbine. Comparisons are made between the full nonequilibrium and conventional equilibrium solutions. Experimental results for the turbine show that the decrease in efficiency between dry and wet operation is underestimated by the theoretical calculation.

Three-Dimensional Blade-Stacking Strategies and Understanding of Flow Physics in Low-Pressure Steam Turbines—Part I: Three-Dimensional Stacking Mechanisms

2015 ◽  
Vol 138 (5) ◽  
Author(s):  
Said Havakechian ◽  
John Denton
Keyword(s):  
Guide Vane ◽  
Three Dimensional ◽  
Low Pressure ◽  
Stagnation Pressure ◽  
Steam Turbines ◽  
Wet Steam ◽  
Pressure Steam ◽  
Computational Fluid Dynamics Cfd ◽  
Last Stage ◽  
3D Stacking

Optimization of blade stacking in the last stage of low-pressure (LP) steam turbines constitutes one of the most delicate and time-consuming parts of the design process. This is the first of two papers focusing on the stacking strategies applied to the last stage guide vane (G0). Following a comprehensive review of the main features that characterize the LP last stage aerodynamics, the three-dimensional (3D) computational fluid dynamics (CFD) code used for the investigation and options related to the modeling of wet steam are described. Aerodynamic problems related to the LP last stage and the principles of 3D stacking are reviewed in detail. In this first paper, the results of a systematic study on an isolated LP stator row are used to elucidate the effects of stacking schemes, such as lean, twist, sweep, and hub profiling. These results show that stator twist not only has the most powerful influence on the reaction variation but it also produces undesirable spanwise variations in angular momentum at stator exit. These may be compensated by introducing a positive stagnation pressure gradient at entry to the last stage.

scholarly journals The applicability of two-tier low pressure turbine in high-power condensing steam turbines

2018 ◽  
Author(s):  
Zaryankin Arkadiy ◽  
Osipov Sergey ◽  
Krutitskii Vladislav
Keyword(s):  
High Power ◽  
Low Pressure ◽  
Steam Turbines ◽  
Low Pressure Turbine

Development of a model for thin films and numerical sensitivity tests

2018 ◽  
Vol 232 (5) ◽  
pp. 525-535 ◽  
Author(s):  
Amélie Simon ◽  
Jean-Marc Dorey ◽  
Michel Lance
Keyword(s):  
Surface Tension ◽  
Shear Stress ◽  
Thin Liquid Film ◽  
Low Pressure ◽  
Liquid Films ◽  
Steam Turbines ◽  
Low Pressure Turbine ◽  
Plane Plate ◽  
Dimensional Version ◽  
The Waves

Because the unsteady behavior of liquid films in steam turbines is a key point for additional friction losses and atomization process (that leads to coarse water generation), the development of a dedicated model has been found necessary. A two-dimensional computational fluid dynamics code for unstructured mesh is being developed using the finite volume method to simulate this thin liquid film. The aim is to predict the formation of the waves in the film since it is suspected to be a key parameter for friction and atomization. Applied as a first step to a plane plate, the code has been verified in a one-dimensional version with analytical solutions and is tested in low-pressure turbine steam conditions. Falling films computations (without gas shear stress) show that the model is capable to reproduce the waves’ shape of experiments from the literature. With steam under low-pressure turbine conditions, and compared to experimental data from the University of Michigan, the model including shear stress and surface tension provides good results for heights. Sensitivity calculations have been undergone showing the crucial influence of the surface tension and the generation of solitary waves for high velocities is captured by the code. The effect of gravity is also quantified.

The Verification of Concentrated Impurities in Low-Pressure Steam Turbines

1983 ◽  
Vol 105 (1) ◽  
pp. 192-198 ◽  
Author(s):  
W. G. Steltz ◽  
P. K. Lee ◽  
W. T. Lindsay
Keyword(s):  
Saturated Vapor ◽  
Field Testing ◽  
Low Pressure ◽  
Steam Turbines ◽  
Expansion Process ◽  
Low Pressure Turbine ◽  
Pressure Steam ◽  
Vapor Line ◽  
Low Levels ◽  
First Time

The problem of corrosion-assisted low-pressure blade failures is discussed from the water chemistry and aerothermodynamic viewpoints. The physical chemistry of particular steam impurities existing in low-pressure steam turbines is reviewed with special applicability to blade path steam conditions. The interaction of the turbine expansion line with the salt solution zone has been verified by field testing which has, for the first time, demonstrated the existence of concentrated impurities within the low pressure turbine blade path. In addition, the existence of low levels of moisture as measured by an optical moisture probe offers strong evidence that the expansion process in low-pressure steam turbines takes place, on the average, in thermodynamic equilibrium, at least in the vicinity of the saturated vapor line.

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