Two Phase Flow CFD Modeling to Enhance Steam Turbines LP Stages Performance Predictability: Comparison With Data and Correlations

2021 ◽  
Author(s):  
Nicola Maceli ◽  
Andrea Arnone ◽  
Lorenzo Arcangeli
Keyword(s):  
Two Phase Flow ◽  
Cfd Modeling ◽  
Phase Flow ◽  
Steam Turbines ◽  
Two Phase

scholarly journals CFD modeling of liquid film reversal of two-phase flow in vertical pipes

2019 ◽  
Vol 9 (4) ◽  
pp. 3039-3070
Author(s):  
Mohamed M. Hussein ◽  
A. Al-Sarkhi ◽  
H. M. Badr ◽  
M. A. Habib
Keyword(s):  
Liquid Film ◽  
Two Phase Flow ◽  
Cfd Modeling ◽  
Phase Flow ◽  
Two Phase

CFD Modeling of the Fast Pyrolysis of Coal in Cold Flow Fluidized Bed

2011 ◽  
Vol 396-398 ◽  
pp. 209-212
Author(s):  
An Ning Zhou ◽  
Tie Shuan Zhang ◽  
Xiu Bin Ren ◽  
Li Zhen Zheng
Keyword(s):  
Fluidized Bed ◽  
Fluidized Beds ◽  
Two Phase Flow ◽  
Fast Pyrolysis ◽  
Cfd Modeling ◽  
Phase Flow ◽  
Two Phase ◽  
Cold Flow ◽  
Solid Phases ◽  
2D Model

Abstract. Gas-solid fluidized beds are widely applied in many industries as reactors or heat/mass transferring units because of their good heterogeneous mixing behaviors and large transferring area between the gas and solid phases. In this study, based on the Eulerian-Eulerian approach, 2D model of gas-solid flow field in fluidized bed is simulated, and the drag force models of Gidaspow and Syamlal-O’Brien have been used to simulate and analyze the two-phase flow for exploring mechanism and interaction laws of two-phase flow.

Computational Fluid Dynamics Modeling of Flow Boiling in Microchannels With Nonuniform Heat Flux

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Daniel Lorenzini ◽  
Yogendra K. Joshi
Keyword(s):  
Fluid Dynamics ◽  
Heat Flux ◽  
Computational Fluid Dynamics ◽  
Phase Change ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Cfd Modeling ◽  
Temperature Phase ◽  
Phase Flow ◽  
Two Phase

The computational fluid dynamics (CFD) modeling of boiling phenomena has remained a challenge due to numerical limitations for accurately simulating the two-phase flow and phase-change processes. In the present investigation, a CFD approach for such analysis is described using a three-dimensional (3D) volume of fluid (VOF) model coupled with a phase-change model accounting for the interfacial mass and energy transfer. This type of modeling allows the transient analysis of flow boiling mechanisms, while providing the ability to visualize in detail temperature, phase, and pressure distributions for microscale applications with affordable computational resources. Results for a plain microchannel are validated against benchmark correlations for heat transfer (HT) coefficients and pressure drop as a function of the heat flux and mass flux. Furthermore, the model is used for the assessment of two-phase cooling in microelectronics under a realistic scenario with nonuniform heat fluxes at localized regions of a silicon microchannel, relevant to the cooling layer of 3D integrated circuit (IC) architectures. Results indicate the strong effect of two-phase flow regime evolution and vapor accumulation on HT. The effects of reduced saturation pressure, subcooling, and flow arrangement are explored in order to provide insight about the underlying physics and cooling performance.

Modeling Two-Phase Flow in Pipe Bends

2004 ◽  
Vol 127 (2) ◽  
pp. 204-209 ◽  
Author(s):  
Savalaxs Supa-Amornkul ◽  
Frank R. Steward ◽  
Derek H. Lister
Keyword(s):  
Pressure Drop ◽  
Single Phase ◽  
Two Phase Flow ◽  
Cfd Modeling ◽  
Phase Flow ◽  
Water Mixture ◽  
Two Phase ◽  
Candu Reactors ◽  
Phase Liquid ◽  
Visualization Experiments

In order to have a better understanding of the interaction between the two-phase steam-water coolant in the outlet feeder pipes of the primary heat transport system of some CANDU reactors and the piping material, themalhydraulic modelling is being performed with a commercial computational fluid dynamics (CFD) code—FLUENT 6.1. The modeling has attempted to describe the results of flow visualization experiments performed in a transparent feeder pipe with air-water mixtures at temperatures below 55°C. The CFD code solves two sets of transport equations—one for each phase. Both phases are first treated separately as homogeneous. Coupling is achieved through pressure and interphase exchange coefficients. A symmetric drag model is employed to describe the interaction between the phases. The geometry and flow regime of interest are a 73 deg bend in a 5.9cm diameter pipe containing water with a Reynolds number of ∼1E5-1E6. The modeling predicted single-phase pressure drop and flow accurately. For two-phase flow with an air voidage of 5–50%, the pressure drop measurements were less well predicted. Furthermore, the observation that an air-water mixture tended to flow toward the outside of the bend while a single-phase liquid layer developed at the inside of the bend was not predicted. The CFD modeling requires further development for this type of geometry with two-phase flow of high voidage.

CFD Modeling Inside an Electrical Submersible Pump in Two-Phase Flow Condition

2009 ◽  
Author(s):  
Lissett Barrios ◽  
Mauricio Gargaglione Prado ◽  
Frank Kenyery
Keyword(s):  
Drag Coefficient ◽  
Bubble Size ◽  
Two Phase Flow ◽  
Flow Behavior ◽  
Cfd Modeling ◽  
Phase Flow ◽  
Submersible Pump ◽  
Cfd Simulations ◽  
Two Phase ◽  
Electrical Submersible Pump

Dynamic multiphase flow behavior inside a mixed flow Electrical Submersible Pump (ESP) has been studied theoretically for the first time. The main goal is to model two-phase flow behavior in an ESP. A three-dimensional CFD model has been developed to describe the operational envelope of the ESP, namely the onset of surging. The theoretical study includes CFD simulations for the prediction of the flow behavior inside the pump. The CFD modeling depends on two important variables, namely the bubble size and the bubble drag coefficient. The bubble size has been measured and a physically based correlation presented in Barrios (2007) is used. A new correlation for the drag coefficient is used (Barrios 2007) as a function of rotational speed and Reynolds number. Single-phase and two-phase flow CFD simulations were carried out to investigate liquid flow field. Results from the CFD simulations are consistent with the experimental data (Barrios 2007).

scholarly journals A Novel Dehumidification Strategy to Reduce Liquid Fraction and Condensation Loss in Steam Turbines

Entropy ◽  
2021 ◽  
Vol 23 (9) ◽  
pp. 1225
Author(s):  
Yan Yang ◽  
Haoping Peng ◽  
Chuang Wen
Keyword(s):  
Two Phase Flow ◽  
Liquid Fraction ◽  
Turbine Blades ◽  
Suction Side ◽  
Phase Region ◽  
Condensation Process ◽  
Phase Flow ◽  
Steam Turbines ◽  
Two Phase ◽  
Nonequilibrium Condensation

Massive droplets can be generated to form two-phase flow in steam turbines, leading to erosion issues to the blades and reduces the reliability of the components. A condensing two-phase flow model was developed to assess the flow structure and loss considering the nonequilibrium condensation phenomenon due to the high expansion behaviour in the transonic flow in linear blade cascades. A novel dehumidification strategy was proposed by introducing turbulent disturbances on the suction side. The results show that the Wilson point of the nonequilibrium condensation process was delayed by increasing the inlet superheated level at the entrance of the blade cascade. With an increase in the inlet superheated level of 25 K, the liquid fraction and condensation loss significantly reduced by 79% and 73%, respectively. The newly designed turbine blades not only remarkably kept the liquid phase region away from the blade walls but also significantly reduced 28.1% averaged liquid fraction and 47.5% condensation loss compared to the original geometry. The results provide an insight to understand the formation and evaporation of the condensed droplets inside steam turbines.

Numerical Study on the Two-Phase Flow for a Gas/Liquid Metal Magnetohydrodynamic Generator

2018 ◽  
Author(s):  
Meng-Ran Liao ◽  
Chun-Hui Dai ◽  
Can Ma ◽  
Yong Liu ◽  
Zheng-Xing Zhao ◽  
...  
Keyword(s):  
Liquid Metal ◽  
Power Systems ◽  
Void Fraction ◽  
Two Phase Flow ◽  
Numerical Study ◽  
Phase Flow ◽  
Steam Turbines ◽  
Two Phase ◽  
Mhd Generator ◽  
Energy Conversion Systems

The gas/liquid metal magnetohydrodynamic generator (G/LM-MHD) with the mixture of gas and liquid metal as working fluids shows a promising future due to recent development of liquid metal cooled nuclear reactors. Previous efforts on the G/LM-MHD energy conversion systems have predicted a higher efficiency than traditional thermodynamics cycle. However, most of the earlier studies focus on the conception designs, feasibility analysis and preliminary experiments, while less attention paid on some specific problems such as the bubble phenomenon in the two-phase flow. Therefore, this paper deals with numerical study on the performance characteristics of the gas/liquid metal two-phase flow in an ideal Faraday-type MHD channel, of which the geometry structure is 30 × 30 × 80 mm cuboid segmentary style. The conductive mixture fluid is composed of nitrogen as the gas phase and gallium as the liquid phase (N2/Ga). The temperature at the channel inlet is about 600 K considering the heat transfer after the mixing chamber, while the inlet velocity is around 10 m/s and gas volumetric void fraction is 50%. The external magnetic field is assumed as 4 Tesla adopting the superconducting technology, which seems essential for MHD industrial practice. Then the simulation is accomplished using a modified two-phase mixture model considering the electromagnetic influence. The simulation results show that the distribution of temperature changes much weaker than pressure and velocity, which agrees with earlier one-dimension analysis. On the other hand, the results characterizes clearly the increase of the void fraction close to the electrodes, which can explain intuitively the decrease of the power-generating capacity. Besides, the power output is predicted to reach maximum 22.5 kW while the voltage is 1.2 V and the power density can be 312.5 MW/m3 which is far beyond traditional steam turbines. This study shows a promising future of the gas/liquid metal MHD generator for the small nuclear plants and power systems.

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