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.

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

scholarly journals Numerical Simulation of Non-Equilibrium Two-Phase Wet Steam Flow through an Asymmetric Nozzle

Fluids ◽  
2017 ◽  
Vol 2 (4) ◽  
pp. 63
Author(s):  
Miah Alam ◽  
Manabu Takao ◽  
Toshiaki Setoguchi
Keyword(s):  
Numerical Simulation ◽  
Steam Flow ◽  
Wet Steam ◽  
Two Phase ◽  
Flow Through ◽  
Wet Steam Flow ◽  
Non Equilibrium

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.

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.

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

scholarly journals An attempt to make a reliable assessment of the wet steam flow field in the de Laval nozzle

2018 ◽  
Vol 54 (9) ◽  
pp. 2675-2681 ◽  
Author(s):  
Sławomir Dykas ◽  
Mirosław Majkut ◽  
Krystian Smołka ◽  
Michał Strozik
Keyword(s):  
Flow Field ◽  
Laval Nozzle ◽  
Steam Flow ◽  
Wet Steam ◽  
Reliable Assessment ◽  
De Laval Nozzle ◽  
Wet Steam Flow

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.

Numerical Investigation of Two-Phase Wet Steam Flow With Spontaneous Condensation Based on Euler S2 Calculation Method

2015 ◽  
Author(s):  
Deying Li ◽  
Huanlong Chen ◽  
Yanping Song ◽  
Ke Cui ◽  
Hiroharu Ooyama
Keyword(s):  
Coordinate System ◽  
Calculation Method ◽  
Steam Flow ◽  
Wet Steam ◽  
Two Phase ◽  
Stream Surface ◽  
Spontaneous Condensation ◽  
Wet Steam Flow ◽  
Pressure Nozzle ◽  
Surface Calculation

The Euler equation suitable for the S2 stream surface calculation is derived in the arbitrary orthogonal coordinate system firstly. The numerical method for the two-phase wet steam flow with the spontaneous condensation is then developed on basis of the Euler S2 calculation code, the Eulerian/Eulerian multiphase model and the classic nucleation theory. To adapt the complex geometry of the turbine blades, the Euler equations for the S2 stream surface calculation method are derived in the body-fitted coordinate system. The mathematical model for the third order TVD scheme with the non-conservative variables is also developed for the gas phase governing equation. The 2nd order NND and the VanLeer scheme are applied to the variable reconstruction and the numerical flux calculation respectively in the liquid equations solving process. The pressure and the droplet radii distribution fit well with the experimental data for both the high pressure nozzle and the low pressure nozzle. The S2 calculation method is also employed to predict the performance of a 3-stage low pressure steam turbine with spontaneous steam condensation, and the reasonable results are obtained. The numerical method developed in the present work is able to predict the real wet steam flow with the spontaneous condensation and its impact on the flow field and the aerodynamic parameters distribution reasonably, supplying a fast and accurate technic and method to the steam turbine design.

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.

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