Unsteady Numerical Study of Wet Steam Flow in a Low Pressure Steam Turbine

2012 ◽  
pp. 437-450 ◽  
Author(s):  
J. Starzmann ◽  
M. V. Casey ◽  
J. F. Mayer
Keyword(s):  
Steam Turbine ◽  
Numerical Study ◽  
Low Pressure ◽  
Steam Flow ◽  
Wet Steam ◽  
Pressure Steam ◽  
Wet Steam Flow

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.

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.

Detailed Numerical Study of the Main Sources of Loss and Flow Behavior in Low Pressure Steam Turbine Exhaust Hoods

2017 ◽  
Author(s):  
Dickson Munyoki ◽  
Markus Schatz ◽  
Damian M. Vogt
Keyword(s):  
Steam Turbine ◽  
Numerical Study ◽  
Flow Behavior ◽  
Low Pressure ◽  
Operating Conditions ◽  
Pressure Recovery ◽  
Exhaust Hood ◽  
Recovery Coefficient ◽  
Pressure Steam ◽  
Underlying Mechanisms

The performance of the axial-radial diffuser downstream of the last low-pressure steam turbine stages and the losses occurring subsequently within the exhaust hood directly influences the overall efficiency of a steam power plant. It is estimated that an improvement of the pressure recovery in the diffuser and exhaust hood by 10% translates into 1% of last stage efficiency [11]. While the design of axial-radial diffusers has been the object of quite many studies, the flow phenomena occurring within the exhaust hood have not received much attention in recent years. However, major losses occur due to dissipation within vortices and inability of the hood to properly diffuse the flow. Flow turning from radial to downward flow towards the condenser, especially at the upper part of the hood is essentially the main cause for this. This paper presents a detailed analysis of the losses within the exhaust hood flow for two operating conditions based on numerical results. In order to identify the underlying mechanisms and the locations where dissipation mainly occurs, an approach was followed, whereby the diffuser inflow is divided into different sectors and pressure recovery, dissipation and finally residual kinetic energy of the flow originating from these sectors is calculated at different locations within the hood. Based on this method, the flow from the topmost sectors at the diffuser inlet is found to cause the highest dissipation for both investigated cases. Upon hitting the exhaust hood walls, the flow on the upper part of the diffuser is deflected, forming complex vortices which are stretching into the condenser and interacting with flow originating from other sectors, thereby causing further swirling and generating additional losses. The detailed study of the flow behavior in the exhaust hood and the associated dissipation presents an opportunity for future investigations of efficient geometrical features to be introduced within the hood to improve the flow and hence the overall pressure recovery coefficient.

Numerical Investigation of the Impact of Part-Span Connectors on Aero-Thermodynamics in a Low Pressure Industrial Steam Turbine

2014 ◽  
Author(s):  
M. Häfele ◽  
J. Starzmann ◽  
M. Grübel ◽  
M. Schatz ◽  
D. M. Vogt ◽  
...  
Keyword(s):  
Steam Turbine ◽  
Numerical Study ◽  
Three Dimensional ◽  
Measurement Data ◽  
Cross Flow ◽  
Low Pressure ◽  
Wet Steam ◽  
Flow Vortex ◽  
The Impact ◽  
Non Equilibrium

A numerical study on the flow in a three stage low pressure industrial steam turbine with conical friction bolts in the last stage and lacing wires in the penultimate stage is presented and analyzed. Structured high-resolution hexahedral meshes are used for all three stages and the meshing methodology is shown for the rotor with friction bolts and blade reinforcements. Modern three-dimensional CFD with a non-equilibrium wet steam model is used to examine the aero-thermodynamic effects of the part-span connectors. A performance assessment of the coupled blades at part load, design and overload condition is presented and compared with measurement data from an industrial steam turbine test rig. Detailed flow field analyses and a comparison of blade loading between configurations with and without part-span connectors are presented in this paper. The results show significant interaction of the cross flow vortex along the part-span connector with the blade passage flow causing aerodynamic losses. This is the first time that part-span connectors are being analyzed using a non-equilibrium wet steam model. It is shown that additional wetness losses are induced by these elements.

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