LES of the Ignition of a Two-Phase Staged Swirling Burner: Influence of Ignition Location and Operating Conditions on the Flame Shape

2021 ◽  
Author(s):  
Leo Cunha Caldeira Mesquita ◽  
Aymeric Vie ◽  
Sebastien Ducruix
Keyword(s):  
Operating Conditions ◽  
Two Phase ◽  
Flame Shape

LES of the Ignition of a Two-Phase Staged Swirling Burner: Influence of Ignition Location and Operating Conditions on the Flame Shape

2020 ◽  
Author(s):  
Léo C. C. Mesquita ◽  
Aymeric Vié ◽  
Sébastien Ducruix
Keyword(s):  
Recirculation Zone ◽  
Control Flow ◽  
Operating Conditions ◽  
Operating Point ◽  
Hysteresis Cycle ◽  
Ignition Process ◽  
Two Phase ◽  
Rate Condition ◽  
Experimental Database ◽  
Flame Shape

Abstract Staged multipoint injection has been developped as an interesting technology to control flow and flame dynamics in Lean Premixed Prevaporized (LPP) swirled gas turbine burners. The BIMER combustor, a two-staged swirling burner composed of a pilot stage and a multipoint stage, has been operated for many years to shed light on the complex phenomena related to such kinds of burners, as well as to build an experimental database for the validation of numerical developments. During the experimental campaigns, several flame archetypes have been encountered, flame shape transitions and a consequent hysteresis cycle were observed depending on the liquid fuel splitting between the stages. As each flame archetype presents different combustion characteristics and thermoacoustic behavior, it is highly relevant to understand how to stabilize such archetypes. In this optics, the objective of the present paper is to investigate ignition as a way to control the final flame archetype. By means of Large Eddy Simulations, we explore different operating conditions and have a direct insight into the flame propagation process. Two operating conditions are simulated: a low and a high flow rate condition. Two simulations are performed for each operating point, one where the ignition kernel is initiated in the Outer Recirculation Zone (ORZ) and the other one where it is initiated in the Central Recirculation Zone (CRZ). In all cases the fuel is injected only through the pilot injector, as in the ignition process during experiments. For the low power point, both ORZ and CRZ ignitions lead to the stabilization of a V-flame. When igniting on the high power operating point, the ORZ ignition results in a M-shaped flame, while the CRZ one results in a tulip shape. These different behavior are analyzed and discussed in the final part of the paper.

The Research of Marine Nuclear Power Two Loop Simulation Software Based on the Thermal System Analysis

2014 ◽  
Vol 983 ◽  
pp. 288-291
Author(s):  
Guo Lei Zhang ◽  
Xiang Dong Jin ◽  
Zhan Zhao ◽  
Zhi Jun Shi
Keyword(s):  
Nuclear Power ◽  
System Analysis ◽  
Simulation Analysis ◽  
Simulation Software ◽  
Operating Conditions ◽  
Two Phase ◽  
Design Data ◽  
Software Optimization ◽  
Power Simulation ◽  
Basic Functions

To study of Nuclear power simulation software's basic functions and mathematical model based on thermal analysis. Describes the two-phase flow model of GSE software superiority, as well as the software optimization program .Use of software tools for normal operating conditions of the simulation calculation and analysis of the results. Comparison with design data shows that,the software use in marine nuclear power two loop system simulation analysis field, the accuracy of it is higher.

Measurement of Liquid Film Thickness for Annular Two-Phase HFC134a Gas-Liquid Ethanol Flow in the Vertical Tube

2021 ◽  
Author(s):  
Huacheng Zhang ◽  
Tutomo Hisano ◽  
Shoji Mori ◽  
Hiroyuki Yoshida
Keyword(s):  
Film Thickness ◽  
Liquid Film ◽  
Thin Liquid Film ◽  
Atmospheric Condition ◽  
Heating Surface ◽  
Operating Conditions ◽  
Liquid Film Thickness ◽  
Two Phase ◽  
Disturbance Waves ◽  
Analytical Approaches

Abstract Annular gas-liquid two-phase flows, such as the flows attached to the fuel rods of boiling water reactors (BWR), are a prevalent occurrence in industrial processes. At the gas-liquid interface of such flows, disturbance waves with diverse velocity and amplitude commonly arise. Since the thin liquid film between two successive disturbance waves leads to the dryout on the heating surface and limits the performance of the BWRs, complete knowledge of the disturbance waves is of great importance for the characterized properties of disturbance waves. The properties of disturbance waves have been studied by numerous researchers through extensive experimental and analytical approaches. However, most of the experimental data and analyses available in the literature are limited to the near atmospheric condition. In consideration of the properties of liquids and gases under atmospheric pressure which are distinct from those under BWR operating conditions (7 MPa, 285 °C), we employed the HFC134a gas and liquid ethanol whose properties at relatively low pressure and temperature (0.7 MPa, 40 °C) are similar to those of steam and water under BWR operating conditions as working fluids in a tubular test section having an inside diameter 5.0mm. Meanwhile, the liquid film thickness is measured by conductance probes. In this study, we report the liquid film thickness characteristics in a two-phase HFC134a gas-liquid ethanol flow. A simple model of the height of a disturbance wave was also proposed.

scholarly journals Development of Hybrid Airlift-Jet Pump with Its Performance Analysis

2018 ◽  
Vol 8 (9) ◽  
pp. 1413 ◽  
Author(s):  
Dan Yao ◽  
Kwongi Lee ◽  
Minho Ha ◽  
Cheolung Cheong ◽  
Inhiug Lee
Keyword(s):  
Boundary Conditions ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Stokes Equations ◽  
Flow Characteristics ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Jet Pump ◽  
Two Phase

A new pump, called the hybrid airlift-jet pump, is developed by reinforcing the advantages and minimizing the demerits of airlift and jet pumps. First, a basic design of the hybrid airlift-jet pump is schematically presented. Subsequently, its performance characteristics are numerically investigated by varying the operating conditions of the airlift and jet parts in the hybrid pump. The compressible unsteady Reynolds-averaged Navier-Stokes equations, combined with the homogeneous mixture model for multiphase flow, are used as the governing equations for the two-phase flow in the hybrid pump. The pressure-based methods combined with the Pressure-Implicit with Splitting of Operators (PISO) algorithm are used as the computational fluid dynamics techniques. The validity of the present numerical methods is confirmed by comparing the predicted mass flow rate with the measured ones. In total, 18 simulation cases that are designed to represent the various operating conditions of the hybrid pump are investigated: eight of these cases belong to the operating conditions of only the jet part with different air and water inlet boundary conditions, and the remaining ten cases belong to the operating conditions of both the airlift and jet parts with different air and water inlet boundary conditions. The mass flow rate and the efficiency are compared for each case. For further investigation into the detailed flow characteristics, the pressure and velocity distributions of the mixture in a primary pipe are compared. Furthermore, a periodic fluctuation of the water flow in the mass flow rate is found and analyzed. Our results show that the performance of the jet or airlift pump can be enhanced by combining the operating principles of two pumps into the hybrid airlift-jet pump, newly proposed in the present study.

A Visual and Photographic Study of the Inception of Vaporization in Adiabatic Flow

1964 ◽  
Vol 86 (2) ◽  
pp. 257-261 ◽  
Author(s):  
E. P. Mikol ◽  
J. C. Dudley
Keyword(s):  
Experimental Method ◽  
Two Phase Flow ◽  
Operating Conditions ◽  
Phase Flow ◽  
Two Phase ◽  
Adiabatic Flow ◽  
Index Data ◽  
Flow Phenomena ◽  
Glass Tubes

Data and observations obtained during the study of two-phase flow phenomena for refrigerants flowing in small bore copper and glass tubes have been examined for their significance to the cavitation. Visual and photographic observations have been made of the inception of vaporization and of the movement of the point of inception as operating conditions are varied. Liquid tension has been deduced as occurring in these tests. Liquid tension and cavitation index data are presented. The experimental method is recommended as a means for studying many aspects of the phenomenon of cavitation.

Experiment of Adiabatic Two-Phase Flow in an Annulus Under Low-Frequency Vibration

2012 ◽  
Author(s):  
Shao-Wen Chen ◽  
Caleb S. Brooks ◽  
Chris Macke ◽  
Takashi Hibiki ◽  
Mamoru Ishii ◽  
...  
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Low Frequency ◽  
Flow Regimes ◽  
Operating Conditions ◽  
Phase Flow ◽  
Two Phase ◽  
Specific Flow ◽  
Low Frequency Vibration ◽  
Fft Analysis

In order to investigate the possible effect of seismic vibration on two-phase flow dynamics and thermal-hydraulics of a nuclear reactor, experimental tests of adiabatic air-water two-phase flow under low-frequency vibration were carried out in this study. An eccentric cam vibration module operated at low motor speed (up to 390rpm) was attached to an annulus test section which was scaled down from a prototypic BWR fuel assembly sub-channel. The inner and outer diameters of the annulus are 19.1mm and 38.1mm, respectively. The two-phase flow operating conditions cover the ranges of 0.03≤<jg> ≤1.46m/s and 0.25≤<jf>≤1.00m/s and the vibration displacement ranges from ±0.8mm to ±22.2mm. Steady-state area-averaged instantaneous and time-averaged void fraction was recorded and analyzed in stationary and vibration experiments. A neural network flow regime identification technique and fast Fourier transformation (FFT) analysis were introduced to analyze the flow regimes and void signals under stationary and vibration conditions. Experimental results reveal possible changes in flow regimes under specific flow and vibration conditions. In addition, the instantaneous void fraction signals were affected and shown by FFT analysis. Possible reasons for the changes include the applied high acceleration and/or induced resonance at certain ports under the specific flow and vibration conditions.

Parametric Analysis of Single-Phase and Two-Phase Models of a Microfluidic Direct Methanol Fuel Cell

2013 ◽  
Author(s):  
Usama Tohid ◽  
Arturo Pacheco-Vega
Keyword(s):  
Fuel Cell ◽  
Parametric Analysis ◽  
Single Phase ◽  
Operating Conditions ◽  
Cell Performance ◽  
Geometrical Parameters ◽  
Two Phase ◽  
Flow Rates ◽  
Direct Methanol ◽  
Phase Models

We perform numerical simulations of single-phase and two-phase models of a direct methanol microfluidic fuel cell (μ-DMFC). The focus of this study is on the parametric analysis of a single channel of the system, for specific sets of operating conditions, in order to map the dependence of the cell performance with respect to the geometrical parameters. Different geometries, ranging from 500 μm to 4 mm in width, and 500 μm to 4 cm in length, along with membrane thicknesses from 50 μm to 500 μm, were considered. The mathematical models are given in terms of the Navier-Stokes, the Butler-Volmer and the Maxwell-Stefan equations, along with Darcy’s equation for the flow across the membrane. The difference between the single- and two-phase flow models lies upon the specific constitutive equations used. For each geometry and operating condition, the two-dimensional equations were solved by a finite element method. The conditions of operation include: flow rates and inlet weight fractions of methanol at the anode and oxygen the cathode. The results from this analysis, presented as polarization curves and power densities, indicate that fuel-cell systems with higher flow rates and inlet weight fraction of methanol achieve the best performance. However, when the concentration of methanol exceeds 2M the cell performance is negatively impacted due to crossover. Comparison of the results indicates that the two-phase model has a more restrictive domain for both the geometrical parameters and operating conditions.

Ex-Situ Characterization of Two-Phase Flow Regimes in Proton-Exchange Membrane Fuel Cells Under Non-Isothermal Conditions

2010 ◽  
Author(s):  
Arganthae¨l Berson ◽  
Jon G. Pharoah
Keyword(s):  
Proton Exchange Membrane ◽  
Two Phase Flow ◽  
Metal Foam ◽  
Flow Regimes ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Ex Situ ◽  
Phase Flow ◽  
Two Phase ◽  
Exchange Membrane

Efficient water management is crucial for the good performances of proton-exchange membrane fuel cells (PEMFCs). The geometric and physical characteristics of the components of a PEMFC as well as operating conditions have an impact on the transport of water through the porous transport layer (PTL) and the two-phase flow regimes in the microchannels. One parameter of importance is the local temperature, which affects properties such as surface tension and is coupled with phase change. Indeed, a temperature difference of about 5K is expected across the PTL, with spatial variations due to the geometry of the flow field plate. We present preliminary results obtained with a first experimental setup for the ex-situ characterization of two-phase flow regimes in the flow channels. Water is pushed through the PTL, which is sandwiched between a porous metal foam and the flow field plate. The air flow rate, temperature and humidity can be controlled. The cell can be heated up by applying an electrical current through the metal foam. A transparent window is located on top of the flow channel. The two-phase flow within the micro-channels is visualized using a high-speed camera and laser-induced fluorescence. Preliminary results obtained under isothermal conditions at room temperature show that different two-phase flow regimes occur in the channels depending on the operating conditions, in good qualitative agreement with data from the literature. Eventually, a new visualization cell is presented that is expected to correct the flaws of the previous design and will allow a better thermal control. It will be possible to adjust the temperature gradient and the mean temperature in order to observe their impact on two-phase flow regimes for different types of PTL and flow rates. The results will provide a better understanding of water transport in PEMFC and benchmark data for the validation of numerical models.

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