Liquid Jet in Cross Flow Modeling

2014 ◽  
Author(s):  
Jayanth Sekar ◽  
Arvind Rao ◽  
Sreedhar Pillutla ◽  
Allen Danis ◽  
Shih-Yang Hsieh
Keyword(s):  
Cross Flow ◽  
Liquid Jet ◽  
Flow Modeling ◽  
Gas Turbine Combustor ◽  
Two Phase ◽  
Droplet Distribution ◽  
Jet In Cross Flow ◽  
Jet Trajectory ◽  
Air Mixing ◽  
Secondary Breakup

All key combustor performance & operability characteristics like emissions, exit profile, durability, LBO etc. have a dependence on spray quality. Hence it is important to accurately predict spray characteristics for accurate combustor modeling. In this paper, a CFD based liquid jet in cross flow spray modeling approach adopted at GE Aviation is presented. Liquid jet in cross flow is a complex phenomenon that broadly involves jet trajectory evolution, surface breakup, column fracture and dispersion of secondary droplet particles. A two-phase steady state Volume of Fluid (VOF) approach is used to predict the liquid jet trajectory. A combination of output from VOF and empirical correlations (Sallam et. al; Oda et. al) is used to predict droplet distribution that includes diameter, velocity components and mass flow rate. Surface breakup is modeled by injecting droplets along the leeward surface of the liquid jet with spanwise perturbation to capture the transverse spread. Jet column breakup is modeled by injecting droplets including effects of unsteady fluctuations empirically to mimic the column fracture behavior. Discrete particles are then transported in a lagrangian frame coupled with secondary breakup of droplets. This approach has been validated on a benchmark quality dataset with an average SMD (Sauter Mean Diameter) error of ∼6 microns and is being used on Gas Turbine combustor fuel-air mixing devices employing liquid jet in cross flow atomizers.

A Validated Two-Phase Flow Large Eddy Simulation Methodology

2013 ◽  
Author(s):  
Feng Xiao ◽  
Mehriar Dianat ◽  
James J. McGuirk
Keyword(s):  
Boundary Conditions ◽  
Level Set ◽  
Two Phase Flow ◽  
Local Level ◽  
Density Ratio ◽  
Cross Flow ◽  
Liquid Jet ◽  
Phase Flow ◽  
Two Phase ◽  
Primary Breakup

A robust two-phase flow LES methodology is described, validated and applied to simulate primary breakup of a liquid jet injected into an airstream in either co-flow or cross-flow configuration. A Coupled Level Set and Volume of Fluid method is implemented for accurate capture of interface dynamics. Based on the local Level Set value, fluid density and viscosity fields are treated discontinuously across the interface. In order to cope with high density ratio, an extrapolated liquid velocity field is created and used for discretisation in the vicinity of the interface. Simulations of liquid jets discharged into higher speed airstreams with non-turbulent boundary conditions reveals the presence of regular surface waves. In practical configurations, both air and liquid flows are, however, likely to be turbulent. To account for inflowing turbulent eddies on the liquid jet interface primary breakup requires a methodology for creating physically correlated unsteady LES boundary conditions, which match experimental data as far as possible. The Rescaling/Recycling Method is implemented here to generate realistic turbulent inflows. It is found that liquid rather than gaseous eddies determine the initial interface shape, and the downstream turbulent liquid jet disintegrates much more chaotically than the non-turbulent one. When appropriate turbulent inflows are specified, the liquid jet behaviour in both co-flow and cross-flow configurations is correctly predicted by the current LES methodology, demonstrating its robustness and accuracy in dealing with high liquid/gas density ratio two-phase systems.

Pratt and Whitney Gas Turbine Combustor Design Using ANSYS Fluent and User Defined Functions

2012 ◽  
Author(s):  
Baris A. Sen ◽  
Yanhu Guo ◽  
Randal G. McKinney ◽  
Federico Montanari ◽  
Frederick C. Bedford
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Cross Flow ◽  
Product Family ◽  
Liquid Jet ◽  
Resource Requirement ◽  
Ansys Fluent ◽  
Systematic Testing ◽  
Jet In Cross Flow ◽  
Break Up

This paper summarizes work conducted at Pratt & Whitney to incorporate ANSYS Fluent into the computational fluid dynamics-based combustor design process. As a first step, turbulence, combustion and spray models that already exist and have been validated in the Pratt & Whitney legacy computational fluid dynamics (CFD) solver ALLSTAR were converted into user defined functions (UDFs) for usage with the core ANSYS Fluent solver. In this manner, a baseline solver was established that allowed a systematic testing of the ANSYS Fluent native models. The baseline solver was validated against computational results as well as experimental data obtained for (i) liquid jet in cross-flow (LJICF), (ii) ambient spray injector tests and (iii) Pratt & Whitney next generation product family configurations. These test cases established a thorough evaluation of ANSYS Fluent with UDFs on a spectrum of simple to complex geometries and flow physics relevant to the conditions encountered in aeroengine combustors. Results show that Fluent produces calculated results obtained by ALLSTAR with similar level of agreement to the experiments. Furthermore, Fluent provides better convergence compared to the legacy ALLSTAR solver with a similar computational resource requirement. The ANSYS Fluent native spray break-up models were also tested for the liquid jet in cross flow configuration, demonstrating the importance of modeling the stripping and primary break-up regime of a spray jet. This capability is currently available only via the use of UDFs.

Fluid-Structure Interactions in a Tube Bundle Subject to Cross-Flow. Part B : Two-Phase Flow Modeling

2014 ◽  
Author(s):  
Eliott R. Tixier ◽  
Cédric R. Béguin ◽  
Stephane Etienne ◽  
Dominique Pelletier ◽  
Alexander Hay ◽  
...  
Keyword(s):  
Two Phase Flow ◽  
Tube Bundle ◽  
Cross Flow ◽  
Phase Flow ◽  
Flow Modeling ◽  
Fluid Structure Interactions ◽  
Two Phase ◽  
Fluid Structure ◽  
Flow Part

Trajectory of a Liquid Jet in a High Temperature and Pressure Gaseous Cross Flow

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Amirreza Amighi ◽  
Nasser Ashgriz
Keyword(s):  
Momentum Flux ◽  
Cross Flow ◽  
Flux Ratio ◽  
Liquid Jet ◽  
Momentum Flux Ratio ◽  
Flow Parameters ◽  
System A ◽  
Air Temperatures ◽  
Jet Trajectory ◽  
Temperature And Pressure

An experimental study of liquid jet injection into subsonic air crossflow is presented. The aim of this study was to relate the jet trajectory to flow parameters, including jet and air velocities, pressure and temperature, as well as a set of nondimensional variables. For this purpose, an experimental setup was developed, which could withstand high temperatures and pressures. Images were captured using a laser-based shadowgraphy system. A total of 209 different conditions were tested and over 72,000 images were captured and processed. The crossflow air temperatures were 25 °C, 200 °C, and 300 °C; absolute crossflow air pressures were 2.1, 3.8, and 5.2 bars, and various liquid and gas velocities were tested for each given temperature and pressure. The results indicate that the trajectory and atomization change when the air and jet velocities are changed while keeping the momentum flux ratio constant. Therefore, it is beneficial to describe the trajectory based on air and jet Weber numbers or momentum flux ratio in combination with one of the Weber numbers. Also, examples are given where both Weber numbers are kept constant but the atomization is changed, and therefore, other terms beyond inertia terms are required to describe the spray behavior. It is also shown that the gas viscosity has to be considered when developing correlations. The correlations that include this term are generally better in predicting the trajectory. Therefore, Ohnesorge numbers in combination with the Weber numbers is used in the present correlations to describe the trajectories.

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