Evaluation and Validation of Two-Phase Flow Numerical Simulations Applied to an Aeronautical Injector Using a Lagrangian Approach

2020 ◽  
Author(s):  
Julien Tillou ◽  
Julien Leparoux ◽  
Jérome Dombard ◽  
Eleonore Riber ◽  
Bénédicte Cuenot
Keyword(s):  
Two Phase Flow ◽  
Operating Conditions ◽  
Spray Angle ◽  
Diameter Distribution ◽  
Phase Flow ◽  
Two Phase ◽  
Experimental Database ◽  
Wall Interaction ◽  
Liquid Mass Flow Rate ◽  
Wall Interactions

Abstract Non-reactive Lagrangian two-phase flow Large-Eddy Simulations (LES) of an industrial aeronautical injector are carried out with the compressible AVBP code and compared with an experimental database in an industrial context. While most of the papers are focused on simplex atomiser with only one fuel passage, we propose to account for specific industrial configurations based on duplex atomiser where both the primary and the secondary passages operate. For the second passage, the fuel spray angle is wider, leading to spray / wall interactions and airblast atomization. The computation domain consists in the experimental mock-up without the fuel atomizer part. The liquid-injection boundary condition is applied through the phenomenological FIM-UR model, which prescribes droplet velocities and diameter distribution at the atomizer tip based on both the atomizer characteristics and the liquid mass flow rate. No specific models are used for spray / wall interaction, and droplets are assumed to slip on the walls. The numerical results are compared with the experimental database for Jet-A1 fuel, built through Phase Doppler Anemometry instrumentation, allowing access to local information regarding the droplets velocity components. Three LES are performed for pressure loss ranging from 1 to 3%, covering an important part of the engine operating conditions, from high altitude relight to cruise operating point. Mean and fluctuating velocity profiles show a relatively good agreement with measurements, for all the operating points. It confirms that the spray/wall interactions, airblast and secondary breakup models may be neglected as a first approximation for configurations where only a relatively small amount of fuel impacts the wall.

Empirical Correlations for Prediction Slug Liquid Holdup on Slug-Pseudo-Slug and Slug-Churn Transitions in Vertical and Inclined Two-Phase Flow

2021 ◽  
pp. 1-13
Author(s):  
Ghassan H. Abdul-Majeed ◽  
Abderraouf Arabi ◽  
Gabriel Soto-Cortes
Keyword(s):  
Two Phase Flow ◽  
Liquid Velocity ◽  
Superior Performance ◽  
Phase Flow ◽  
Liquid Viscosity ◽  
Empirical Correlations ◽  
Liquid Holdup ◽  
Two Phase ◽  
Experimental Database ◽  
Transition Models

Summary Most of the existing slug (SL) to churn (CH) or SL to pseudo-slug (PS) transition models (empirical and mechanistic) account for the effect of the SL liquid holdup (HLS). For simplicity, some of these models assume a constant value of HLS in SL/CH and SL/PS flow transitions, leading to a straightforward solution. Other models correlate HLS with different flow variables, resulting in an iterative solution for predicting these transitions. Using an experimental database collected from the open literature, two empirical correlations for prediction HLS at the SL/PS and SL/CH transitions (HLST) are proposed in this study. This database is composed of 1,029 data points collected in vertical, inclined, and horizontal configurations. The first correlation is developed for medium to high liquid viscosity two-phase flow (μL > 0.01 Pa·s), whereas the second one is developed for low liquid viscosity flow (μL ≤ 0.01 Pa·s). Both correlations are shown to be a function of superficial liquid velocity (VSL), liquid viscosity (μL), and pipe inclination angle (θ). The proposed correlations in a combination with the HLS model of Abdul-Majeed and Al-Mashat (2019) have been used to predict SL/PS and SL/CH transitions, and very satisfactory results were obtained. Furthermore, the SL/CH model of Brauner and Barnea (1986) is modified by using the proposed HLST correlations, instead of using a constant value. The modification results in a significant improvement in the prediction of SL/CH and SL/PS transitions and fixes the incorrect decrease of superficial gas velocity (VSG) with increasing VSL. The modified model follows the expected increase of VSG for high VSL, shown by the published observations. The proposed combinations are compared with the existing transition models and show superior performance among all models when tested against 357 measured data from independent studies.

Analysis of Flow-Induced Vibration Due to Stratified Wavy Two-Phase Flow

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
Shuichiro Miwa ◽  
Takashi Hibiki ◽  
Michitsugu Mori
Keyword(s):  
Two Phase Flow ◽  
Dynamic Properties ◽  
Fluid Model ◽  
Dominant Frequency ◽  
Phase Flow ◽  
Flow Induced Vibration ◽  
Two Phase ◽  
Pipe Bend ◽  
Experimental Database ◽  
Force Fluctuation

Fluctuating force induced by horizontal gas–liquid two-phase flow on 90 deg pipe bend at atmospheric pressure condition is considered. Analysis was conducted to develop a model which is capable of predicting the peak force fluctuation frequency and magnitudes, particularly at the stratified wavy two-phase flow regime. The proposed model was developed from the local instantaneous two-fluid model, and adopting guided acoustic theory and dynamic properties of one-dimensional (1D) waves to consider the collisional force due to the interaction between dynamic waves and structure. Comparing the developed model with experimental database, it was found that the main contribution of the force fluctuation due to stratified wavy flow is from the momentum and pressure fluctuations, and collisional effects. The collisional effect is due to the fluid–solid interaction of dynamic wave, which is named as the wave collision force. Newly developed model is capable of predicting the force fluctuations and dominant frequency range with satisfactory accuracy for the flow induced vibration (FIV) caused by stratified wavy two-phase flow in 52.5 mm inner diameter (ID) pipe bend.

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.

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.

scholarly journals Overview of Void Fraction Measurement Techniques, Databases and Correlations for Two-Phase Flow in Small Diameter Channels

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 216
Author(s):  
Álvaro Roberto Gardenghi ◽  
Erivelto dos Santos Filho ◽  
Daniel Gregório Chagas ◽  
Guilherme Scagnolatto ◽  
Rodrigo Monteiro Oliveira ◽  
...  
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Measurement Techniques ◽  
Small Diameter ◽  
Phase Flow ◽  
Two Phase ◽  
Channel Diameter ◽  
Experimental Database ◽  
Absolute Relative Error ◽  
Fraction Measurement

Void fraction is one of the most important parameters for the modeling and characterization of two-phase flows. This manuscript presents an overview of void fraction measurement techniques, experimental databases and correlations, in the context of microchannel two-phase flow applications. Void fraction measurement techniques were reviewed and the most suitable techniques for microscale measurements were identified along its main characteristics. An updated void fraction experimental database for small channel diameter was obtained including micro and macrochannel two-phase flow data points. These data have channel diameter ranging from 0.5 to 13.84 mm, horizontal and vertical directions, and fluids such as air-water, R410a, R404a, R134a, R290, R12 and R22 for both diabatic and adiabatic conditions. New published void fraction correlations as well high cited ones were evaluated and compared to this small-diameter void fraction database in order to quantify the prediction error of them. Moreover, a new drift flux correlation for microchannels was also developed, showing that further improvement of available correlations is still possible. The new correlation was able to predict the microchannel database with mean absolute relative error of 9.8%, for 6% of relative improvement compared to the second-best ranked correlation for small diameter channels.

Micro-Scale Two-Phase Flow Heat Transport Device Driven by Electrohydrodynamic Conduction Pumping

2013 ◽  
Author(s):  
Viral K. Patel ◽  
Jamal Seyed-Yagoobi
Keyword(s):  
Heat Transport ◽  
Two Phase Flow ◽  
Operating Conditions ◽  
Electrode Spacing ◽  
Working Fluid ◽  
Phase Flow ◽  
Two Phase ◽  
Micro Scale ◽  
Flow Heat ◽  
Transport Device

Micro-scale two-phase flow heat transport involves specialized devices that are used to remove large amounts of heat from small surface areas. They operate by circulating a working fluid through a heated space which causes phase change from liquid to vapor. During this process, a significant amount of heat is transported away from the heat source. Micro-scale heat transport devices are compact in size and the heat transfer coefficient can be orders of magnitude higher than in macro-scale for similar operating conditions. Thus, it is of interest to develop such devices for cooling of next-generation electronics and other applications with extremely large heat fluxes. The heat transport device presented in this paper is driven by electrohydrodynamic (EHD) conduction pumping. In EHD conduction pumping, when an electric field is applied to a dielectric liquid, flow is induced. The pump is installed in a two-phase flow loop and has a circular 1 mm diameter cross section with electrode spacing on the order of 120 μm. It acts to circulate the fluid in the loop and has a simple yet robust, non-mechanical design. Results from two-phase flow experiments show that it is easily controlled and such electrically driven pumps can effectively be used in heat transport systems.

Numerical Modeling of Two-Phase Flow Distribution Inside Evaporator Headers

2014 ◽  
Vol 6 (3) ◽  
Author(s):  
Miad Yazdani ◽  
Abbas A. Alahyari ◽  
Hailing Wu ◽  
Thomas D. Radcliff
Keyword(s):  
Heat Exchanger ◽  
Two Phase Flow ◽  
Flow Distribution ◽  
Operating Conditions ◽  
Phase Flow ◽  
Predictive Tool ◽  
Two Phase ◽  
Imaging Results ◽  
Discretization Schemes ◽  
Long Time

Two-phase flow distribution inside evaporator headers has been a challenging problem for a long time and having a robust predictive tool could substantially alleviate the costs associated with experimentation with different concepts and configurations. The use of a two-phase CFD model to predict flow distribution inside the header and at the discharge ports is demonstrated in this paper. The numerical domain is comprised of an inlet pipe and a distributor tube representing the header with a series of discharge ports. The flow distribution was initially verified using an air–water experiment, where the two-phase modeling approach, mesh requirements, and discretization schemes were defined. Next, the model was used to predict distribution of R134a in a typical heat exchanger distributor. The flow distribution across the discharge ports was provided to a discretized correlation-based heat exchanger model to predict the temperature and quality distribution along the length of the heat exchanger. The resultant temperature distribution is validated against IR imaging results for various operating conditions and header orientations.

Flow-Induced Vibration Model for Steam Generator Tubes in Two-Phase Flow

2008 ◽  
Author(s):  
Njuki W. Mureithi ◽  
Soroush Shahriary ◽  
Michel J. Pettigrew
Keyword(s):  
Force Field ◽  
Steam Generator ◽  
Two Phase Flow ◽  
Operating Conditions ◽  
Phase Flow ◽  
Two Phase Flows ◽  
Two Phase ◽  
Fluid Force ◽  
Vibration Stability ◽  
Steam Generator Tubes

While steam generators operate in two-phase flow, the complex nature of the flow makes the prediction of flow-induced fluidelastic instability of steam generator tubes a challenging problem yet to be solved. In the work reported here, the quasi-static fluid force-field, which is the important unknown for two-phase flows, is measured in a rotated-triangle tube bundle for a series of void fractions and flow velocities. The forces are shown to be strongly dependent on void fraction, flow rates and relative tube positions. The fluid force field is then employed along with quasi-steady vibration stability models, originally developed for single phase flows, to model the two-phase flow problem and predict the critical instability velocity. The results are compared with dynamic vibration stability tests and are shown to be in good agreement. The present work uncovers some of the complexities of the fluid force field in two-phase flows. The database provides new potential to designers to estimate expected fluid dynamic loads under operating conditions. The force field data may also be applied in dynamic computations for tube wear simulations, replacing the simple Connors’ model which is currently used.

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