Modelling and Validation of Wet Steam Flow in a Low Pressure Steam Turbine

2011 ◽  
Author(s):  
Jo¨rg Starzmann ◽  
M. Schatz ◽  
M. V. Casey ◽  
J. F. Mayer ◽  
Frank Sieverding
Keyword(s):  
Steam Turbine ◽  
Droplet Size ◽  
Low Pressure ◽  
Numerical Results ◽  
Steam Flow ◽  
Droplet Growth ◽  
Wet Steam ◽  
Test Rig ◽  
Pressure Steam ◽  
Wet Steam Flow

Results of numerical investigations of the wet steam flow in a three stage low pressure steam turbine test rig are presented. The test rig is a scale model of a modern steam turbine design and provides flow measurements over a range of operating conditions which are used for detailed comparisons with the numerical results. For the numerical analysis a modern CFD code with user defined models for specific wet steam modelling is used. The effect of different theoretical models for nucleation and droplet growth are examined. It is shown that heterogeneous condensation is highly dependent on steam quality and, in this model turbine with high quality steam, a homogeneous theory appears to be the best choice. The homogeneous theory gives good agreement between the test rig traverse measurements and the numerical results. The differences in the droplet size distribution of the three stage turbine are shown for different loads and modelling assumptions. The different droplet growth models can influence the droplet size by a factor of two. An estimate of the influence of unsteady effects is made by means of an unsteady two-dimensional simulation. The unsteady modelling leads to a shift of nucleation into the next blade row. For the investigated three stage turbine the influence due to wake chopping on the condensation process is weak but to confirm this conclusion further investigations are needed in complete three dimensions and on turbines with more stages.

Study on Effects of Spontaneous Condensation on Performance of Low Pressure Stages in a Steam Turbine

2006 ◽  
Author(s):  
Liang Li ◽  
Zhenping Feng ◽  
Guojun Li
Keyword(s):  
Steam Turbine ◽  
Stokes Equations ◽  
Low Pressure ◽  
Steam Flow ◽  
Vapor Flow ◽  
Wet Steam ◽  
Water Droplets ◽  
Flow Angle ◽  
Spontaneous Condensation ◽  
Wet Steam Flow

The formation of water droplets in low-pressure steam turbine seriously degrades the performance of the turbine. In order to simulate the wet steam flow with spontaneous condensation, an Eulerian/Eulerian model was developed, in which the Navier-Stokes equations for water vapor flow are coupled with two additional equations describing the formation and the distributions of water droplets. The classical condensation theory was used to model the condensation process. With this model, the three dimensional (3D) steady wet steam flow with spontaneous condensation in three low pressure (LP) stages of an industrial steam turbine was numerically investigated and the results were compared with those in superheated flow. The distribution of pressure, the enthalpy drop, the reaction degree, the outflow velocity and flow angle in each wet steam turbine stage obviously change due to the spontaneous condensation in wet steam flow, compare to those in the superheated flow. The re-distribution of flow parameters in condensing flow leads to that the turbine stages run at ‘off-design’ condition actually, which leads to additional efficiency losses besides the well-known non-equilibrium losses.

scholarly journals Numerical investigation of condensing flow of low pressure steam turbine at different flow rate conditions

2017 ◽  
Vol 21 (suppl. 1) ◽  
pp. 161-167 ◽  
Author(s):  
Kezhen Huang ◽  
Lin Cai ◽  
Jianshu Gao ◽  
Zhuo Liu ◽  
Xinggang Yu
Keyword(s):  
Steam Turbine ◽  
Numerical Investigation ◽  
Low Pressure ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Wet Steam ◽  
Pressure Steam ◽  
Static Performance ◽  
Wet Steam Flow ◽  
Two Stages

The numerical investigation on the wet steam flow in the last two stages of a 1000 MW fossil-fired low pressure steam turbine is presented in this paper. The non-equilibrium model via the classical nucleation theory is employed to simulate the condensing flow of the wet steam. The characteristics of the flow filed from design condition to low volume flow condition are calculated and the static performance of last stage moving blade is also obtained. The development of the backflow phenomenon is clearly captured through the analysis of the velocity triangle.

Unsteady Wake and Vortex Interactions in 3-D Steam Turbine Low Pressure Final Three Stages

2014 ◽  
Author(s):  
Satoshi Miyake ◽  
Itsuro Koda ◽  
Satoru Yamamoto ◽  
Yasuhiro Sasao ◽  
Kazuhiro Momma ◽  
...  
Keyword(s):  
Steam Turbine ◽  
Low Pressure ◽  
Future Perspective ◽  
Wet Steam ◽  
Vortex Interactions ◽  
Unsteady Wake ◽  
Pressure Steam ◽  
Three Stages ◽  
Nonequilibrium Condensation ◽  
Wet Steam Flow

A practical unsteady 3-D wet-steam flow through stator-rotor blade rows in a low-pressure steam turbine final three stages is numerically investigated. In ASME Turbo Expo 2013, we presented numerical results of unsteady 3-D wet-steam flows through three-stage stator-rotor low-aspect blade rows in a low-pressure steam turbine model designed by Mitsubishi Heavy Industry (MHI) assuming nonequilibrium condensation. The last study is extended to the final three stages with large aspect blade rows. The discussion in this paper is mainly focused on the effect of unsteady wake and vortex interactions on nonequilibrium condensation computed by our in-house code “Numerical Turbine System (NTS)”. In addition, the NTS and the future perspective are also briefly introduced.

Eulerian-Lagrangian Numerical Simulation of Wet Steam Flow Through Multi-Stage Steam Turbine

2013 ◽  
Author(s):  
Yasuhiro Sasao ◽  
Satoshi Miyake ◽  
Kenji Okazaki ◽  
Satoru Yamamoto ◽  
Hiroharu Ooyama
Keyword(s):  
Steam Turbine ◽  
Turbine Blades ◽  
Steam Flow ◽  
Droplet Growth ◽  
Computational Domain ◽  
Steam Turbines ◽  
Wet Steam ◽  
Multi Stage ◽  
Flow Through ◽  
Wet Steam Flow

In this paper, we present an inclusive tracking algorithm for water droplets in a wet steam flow through a multi-stage steam turbine. This algorism is based on the Eulerian-Lagrangian coupled solver. The solver continuously computes water droplet growth, kinematic non-equilibrium between vapor and droplets, capture and kinetics of droplets on turbine blades, departure of large droplets from the trailing edge of blades, acceleration and atomization of large droplets, and recollisions between blades and droplets. Our Eulerian-Lagrangian coupled solver is used to predict wetness in unsteady three-dimensional (3D) wet steam flows through three-stage stator rotor cascade channels in a low pressure (LP) steam turbine model which is developed by Mitsubishi Heavy Industries (MHI). Droplet groups tracked by the discrete droplet model (DDM) are placed in the computational domain according to the predicted wetness. Interference from the gas phase on the droplets is considered, to track their kinetic and behavior, until they reach the outlet of the computational domain. The aim of this research is to investigate those multi-physics phenomena that trigger all forms of loss in steam turbines. In addition, this method will also be applied to multi-physics problems such as erosion in future work. This paper is presented as a first step in the research. Overviews of model of current coupling solver and several test calculations are presented.

scholarly journals Unsteady Wet Steam Flow Measurements in a Low-Pressure Test Steam Turbine

2016 ◽  
Vol 9 (1) ◽  
pp. 85-94 ◽  
Author(s):  
Chongfei Duan ◽  
Koji Ishibashi ◽  
Shigeki Senoo ◽  
Ilias Bosdas ◽  
Michel Mansour ◽  
...  
Keyword(s):  
Steam Turbine ◽  
Low Pressure ◽  
Steam Flow ◽  
Wet Steam ◽  
Flow Measurements ◽  
Pressure Test ◽  
Wet Steam Flow

Some Experiments on Wet Steam Flow Visualization in Large Steam Turbine Blading

1976 ◽  
Vol 98 (3) ◽  
pp. 573-577 ◽  
Author(s):  
J. Krzyz˙anowski ◽  
B. Weigle
Keyword(s):  
Steam Turbine ◽  
Steam Flow ◽  
Light Sources ◽  
Phase Flow ◽  
Wet Steam ◽  
Experimental Conditions ◽  
Advantages And Disadvantages ◽  
Primary Droplet ◽  
Last Stage ◽  
Wet Steam Flow

In a series of experiments aimed at the visualization of the wet steam flow in the exhaust part of a 200 MW condensing steam turbine a set of periscopes and light sources was used. The aim of the experiment was: 1 – The investigation of the liquid-phase flow over the last stage stator blading of the turbine mentioned. 2 – The investigation of the gaseous-phase flow through the last stage blading at full and part load. The first part of the program partially failed due to the opaqueness of the wet steam atmosphere for the turbine load higher than 10–20 MW. The detailed experimental conditions will be described. An assessment of the primary droplet size will also be given. The preliminary results of the second part of the program will be outlined. The advantages and disadvantages of the equipment used will be discussed.

Influence of Turbulence Modelling to Condensing Steam Flow in the 3D Low-Pressure Steam Turbine Stage

2016 ◽  
Author(s):  
Yogini Patel ◽  
Giteshkumar Patel ◽  
Teemu Turunen-Saaresti
Keyword(s):  
Steam Turbine ◽  
Stokes Equations ◽  
Turbine Blades ◽  
Rapid Change ◽  
Low Pressure ◽  
Turbulence Modelling ◽  
Steam Flow ◽  
Droplet Growth ◽  
Steam Turbines ◽  
Turbine Stage

With the tremendous role played by steam turbines in power generation cycle, it is essential to understand the flow field of condensing steam flow in a steam turbine to design an energy efficient turbine because condensation at low pressure (LP) turbine introduces extra losses, and erosion in turbine blades. The turbulence has a leading role in condensing phenomena which involve a rapid change of mass, momentum and heat transfer. The paper presents the influence of turbulence modelling on non-equilibrium condensing steam flows in a LP steam turbine stage adopting CFD code. The simulations were conducted using the Eulerian-Eulerian approach, based on Reynolds-averaged Navier-Stokes equations coupled with a two equation turbulence model, which is included with nucleation and droplet growth model for the liquid phase. The SST k-ω model was modified, and the modifications were implemented in the CFD code. First, the performance of the modified model is validated with nozzles and turbine cascade cases. The effect of turbulence modelling on the wet-steam properties and the loss mechanism for the 3D stator-rotor stage is discussed. The presented results show that an accurate computational prediction of condensing steam flow requires the turbulence to be modelled accurately.

Numerical Solution of Wet Steam Flow through Blade Cascade

2016 ◽  
Vol 821 ◽  
pp. 31-38
Author(s):  
Vladimír Hric ◽  
Jan Halama
Keyword(s):  
Equations Of State ◽  
Suction Side ◽  
Steam Flow ◽  
Droplet Growth ◽  
Wet Steam ◽  
Two Phase ◽  
Blade Cascade ◽  
Flow Through ◽  
Wet Steam Flow ◽  
Non Equilibrium

The paper concerns with the numerical modeling of wet steam flow through a blade cascade in transonic regime with non-equilibrium condensation in 2D. Real thermodynamics of vapor phase is implemented in the way which mostly avoid iterations in order to calculate thermodynamic properties. This equation of state is represented by the function for non-dimensional entropy with independent variables scaled density and scaled internal energy. Other equations of state are used for comparison, namely special gas equation which comes from IAPWS-95 formulation and simple pseudo perfect gas relation. We applied simple homogeneous non-equilibrium approach to model two-phase flow. Laminar compressible Navier-Stokes system of equations is used for the mixture properties. Liquid phase is described by the standard method of moments of droplet number distribution function. We consider obtained numerical results to be in good agreement with the measured data. We note the fact that robust and accurate closure of supplementary liquid system (nucleation rate and droplet growth model) is still not available and most often ad-hoc corrections are proposed by the authors. Results show differences among used equations of state as well. This is apparent mainly in the vicinity of condensation shock region on the suction side.

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