A novel method for measuring the coarse water droplets in wet steam flow in steam turbines

2001 ◽  
Vol 10 (2) ◽  
pp. 123-126 ◽  
Author(s):  
Xiaoshu Cai ◽  
Lili Wang ◽  
Yongzhi Pan ◽  
Xin Ouyan ◽  
Jianqi Shen
Keyword(s):  
Steam Flow ◽  
Steam Turbines ◽  
Wet Steam ◽  
Water Droplets ◽  
Novel Method ◽  
Wet Steam Flow

The Effects of Water Injections in Wet Steam Flow in Different Regions of a Mini Laval Nozzle

2008 ◽  
Author(s):  
M. R. Mahpeykar ◽  
E. Amirirad ◽  
E. Lakzian
Keyword(s):  
Nucleation Rate ◽  
Laval Nozzle ◽  
Pressure Rise ◽  
Steam Flow ◽  
Steam Turbines ◽  
Wet Steam ◽  
Water Droplets ◽  
Two Phase ◽  
Condensation Shock ◽  
Wet Steam Flow

Progress in the development of the steam turbines brings about a renewal of interest in wetness associated problems. In turbine steam expansion, the vapour first supercools and then condenses spontaneously to become a two phase mixture. The flow initially is single phase but after Wilson point water droplets are developed and there is a non equilibrium two phase flow. The formation and behavior of the liquid create problems that lower the performance of the turbine wet stage and the mechanisms underlying this are insufficiently understood. This growing droplets release their latent heat to the flow and this heat addition to the supersonic flow cause a pressure rise called condensation shock. Because of irreversible heat transfer in this region the entropy will increase tremendously. Removal of condensates from wet steam flow in the last stage of steam turbines significantly promotes stage efficiency and prevents erosion of rotors. The following study investigates the spraying water droplets at inlet and at throat of mini Laval nozzle and their effects on nucleation rate and condensation shock. According to the results, the nucleation rate is considerably suppressed and therefore the condensation shock nearly disappeared. In other words the injecting droplets would decrease the thermodynamic losses or improve the turbine efficiency.

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 CFD analysis of optical probe interaction with wet steam flow field

2018 ◽  
Vol 180 ◽  
pp. 02045 ◽  
Author(s):  
Michal Kolovratník ◽  
Gukchol Jun ◽  
Ondřej Bartoš
Keyword(s):  
Flow Field ◽  
High Pressures ◽  
Optical Probe ◽  
Steam Flow ◽  
Steam Turbines ◽  
Wet Steam ◽  
Water Steam ◽  
Flow Geometry ◽  
Phase Size ◽  
Wet Steam Flow

In the frame of the measurement feasibility study of the liquid phase size distribution structure in steam turbines at intermediate and high pressures, on CTU the interaction of optical probes with the wet steam flow field is investigated. In order to validate and refine the existing knowledge, a new series of CFD simulations were performed, considering turbine flow geometry, water steam characteristics according to IAPWS97 formulation, and improved boundary conditions and quality of the computing mesh. This paper briefly presents the newly obtained results

Investigation of wet steam flow in a 300 MW direct air-cooling steam turbine. Part 1: Measurement principles, probe, and wetness

2009 ◽  
Vol 223 (5) ◽  
pp. 625-634 ◽  
Author(s):  
X Cai ◽  
T Ning ◽  
F Niu ◽  
G Wu ◽  
Y Song
Keyword(s):  
Steam Turbine ◽  
Steam Flow ◽  
Light Extinction ◽  
Air Cooling ◽  
Steam Turbines ◽  
Wet Steam ◽  
The North ◽  
Multi Wavelength ◽  
Wet Steam Flow ◽  
Short Time

The direct air-cooling steam turbines have been operated more and more in the north of China. The backpressure of a turbine is affected easily with weather and varies very often in a short time. The variation of backpressure in a larger range from about 10 to 60 kPa causes many problems in design and operation of the turbine. To study the properties of the wet steam flow in the low pressure direct air-cooling steam turbine, an optical—pneumatic probe was developed based on the multi-wavelength light extinction and four-hole wedge probe. Measurements with this probe in a 300 MW direct air-cooling turbine were carried out. The measured local wetness, total wetness of exhaust steam, size distribution of fine droplets, and their profiles along the blade height are presented. The measured cylinder efficiency and total wetness agree well with the results obtained by the thermal performance tests.

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.

High Pressure Subsonic Nucleation in 1D Nozzles — An Experimental Study

2014 ◽  
Author(s):  
Tao Guo ◽  
Mark Burnett ◽  
Norman Turnquist ◽  
Francisco Moraga
Keyword(s):  
Experimental Study ◽  
High Pressure ◽  
Wilson Line ◽  
Experimental Studies ◽  
Steam Flow ◽  
Steam Turbines ◽  
Wet Steam ◽  
Flow Conditions ◽  
Test Rig ◽  
Wet Steam Flow

The presence of moisture in steam turbines is known to cause blade erosion and reduce turbine performance. As a result, nucleating wet steam flow has been the topic of both academic and engineering research for many decades. However, almost all of the previous experimental studies on steam nucleation have been carried out under low pressure supersonic flow conditions, either in converging-diverging (Laval) nozzles or in supersonic airfoil cascades. Some recent experimental studies conducted droplet size/wetness measurements within actual turbines, but these tests in general only give qualitative assessment on the nucleation phenomena. They are not intended to study the mechanisms of the nucleating steam flow. In this paper, an experimental study of nucleating wet steam flow under high-pressure subsonic flow conditions is presented. In particular, the world’s first high-pressure subsonic nucleation test rig was designed and built at the GE Global Research Center. This advanced test rig takes high pressure (up to 1000 psia) clean steam with controlled inlet superheat and expands it through 1D subsonic nozzles. The Wilson line location and the length of the nucleation zone are controlled through different combinations of inlet steam pressure and superheat, and overall pressure ratios. An advanced optical measurement system was developed and used to measure the Wilson line, the ensuing condensation zone, and the droplet size and number density generated from nucleation. The flow path in the nozzle is visible through specially designed sapphire windows. The optical system is essentially comprised of two laser-photodiode pairs (405 nm and 689 nm wavelength), which can be traversed along the length of the nozzle. The experiment data have indicated that significant differences exist between high pressure subsonic nucleation and low pressure supersonic nucleation. Further, an in-house 1D analytical tool as well as a 3D multiphase CFD have been used to model the test runs, and reasonable agreements have been obtained. This study has direct application in the design of Nuclear and Concentrated Solar high pressure steam turbines.

Wet steam flow and condensation loss in turbine blade cascades

2021 ◽  
Vol 189 ◽  
pp. 116748
Author(s):  
Chuang Wen ◽  
Yan Yang ◽  
Hongbing Ding ◽  
Chunqian Sun ◽  
Yuying Yan
Keyword(s):  
Turbine Blade ◽  
Steam Flow ◽  
Wet Steam ◽  
Wet Steam Flow

A fast response miniature probe for wet steam flow field measurements

2016 ◽  
Vol 27 (12) ◽  
pp. 125901
Author(s):  
Ilias Bosdas ◽  
Michel Mansour ◽  
Anestis I Kalfas ◽  
Reza S Abhari
Keyword(s):  
Flow Field ◽  
Field Measurements ◽  
Fast Response ◽  
Steam Flow ◽  
Wet Steam ◽  
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.

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