High Fidelity Simulation of the Spray Generated by a Realistic Swirling Flow Injector

2013 ◽  
Author(s):  
X. Li ◽  
M. C. Soteriou ◽  
W. Kim ◽  
J. M. Cohen ◽  
M. Herrmann ◽  
...  
Keyword(s):  
Adaptive Mesh Refinement ◽  
Fuel Injection ◽  
Swirling Flow ◽  
Density Ratio ◽  
Adaptive Mesh ◽  
Uniform Grid ◽  
High Fidelity ◽  
Engine Fuel ◽  
Time Step ◽  
Two Phase

Practical aero-engine fuel injection systems are highly complicated, combining complex fuel atomizer and air swirling elements to achieve good fuel-air mixing as well as long residence time in order to enhance both combustion efficiency and stability. While detailed understanding of the multiphase flow processes occurring in a realistic injector has been limited due to the complex geometries and the challenges in near-field measurements, high fidelity, first principles simulation offers, for the first time, the potential for a comprehensive physics-based understanding. In this work, such simulations have been performed to investigate the spray atomization and subsequent droplet transport in a swirling air stream generated by a complex multi-nozzle/swirler combination. A Coupled Level Set and Volume Of Fluid (CLSVOF) approach is used to directly capture the liquid-gas interface and an embedded boundary (EB) method is applied to flexibly handle the complex injector geometry. The ghost fluid (GF) method is also used to facilitate simulations at realistic fuel-air density ratio. Adaptive mesh refinement (AMR) and Lagrangian droplet models are used to efficiently resolve the multi-scale processes. To alleviate the global constraint on the time-step imposed by locally activated AMR near liquid jets, a separate AMR simulation focusing on jet atomization was performed for relatively short physical time and the resulting Lagrangian droplets are coupled into another simulation on a uniform grid at larger time-steps. The high cost simulations were performed at the U.S. Department of Defense high performance computing facilities using over 5000 processors. Experiments at the same flow conditions were conducted at UTRC. The simulation details of flow velocity and vorticity due to the interaction of the fuel jet and swirling air are presented. The velocity magnitude is compared with experimental measurement at two downstream planes. The two-phase spray spreading is compared with experimental images and the flow details are further analyzed to enhance understanding of the complex physics.

High Fidelity Simulation of the Spray Generated by a Realistic Swirling Flow Injector

2014 ◽  
Vol 136 (7) ◽  
Author(s):  
Xiaoyi Li ◽  
Marios C. Soteriou ◽  
Wookyung Kim ◽  
Jeffrey M. Cohen
Keyword(s):  
Adaptive Mesh Refinement ◽  
Fuel Injection ◽  
Swirling Flow ◽  
Density Ratio ◽  
Adaptive Mesh ◽  
Uniform Grid ◽  
High Fidelity ◽  
Engine Fuel ◽  
Time Step ◽  
Two Phase

Practical aero-engine fuel injection systems are highly complicated, combining complex fuel atomizer and air swirling elements to achieve good fuel-air mixing and long residence time in order to enhance both the combustion efficiency and stability. While a detailed understanding of the multiphase flow processes occurring in a realistic injector has been limited due to the complex geometries and the challenges in near-field measurements, high fidelity, first principles simulation offers, for the first time, the potential for a comprehensive physics-based understanding. In this work, such simulations have been performed to investigate the spray atomization and subsequent droplet transport in a swirling air stream generated by a complex multinozzle/swirler combination. A coupled level set and volume of fluid (CLSVOF) approach is used to directly capture the liquid-gas interface and an embedded boundary (EB) method is applied to flexibly handle the complex injector geometry. The ghost fluid (GF) method is also used to facilitate simulations at a realistic fuel-air density ratio. Adaptive mesh refinement (AMR) and Lagrangian droplet models are used to efficiently resolve the multiscale processes. To alleviate the global constraint on the time step imposed by the locally activated AMR near liquid jets, a separate AMR simulation focusing on jet atomization was performed for a relatively short physical time and the resulting Lagrangian droplets are coupled into another simulation on a uniform grid at larger time-steps. The high cost simulations were performed at the U.S. Department of Defense high performance computing facilities using over 5000 processors. Experiments at the same flow conditions were conducted at the United Technologies Research Center (UTRC). The simulation details of flow velocity and vorticity due to the interaction of the fuel jet and swirling air are presented. The velocity magnitude is compared with the experimental measurement at two downstream planes. The two-phase spray spreading is compared with experimental images and the flow details are further analyzed to enhance the understanding of the complex physics.

Efficient Two-dimensional Acoustic Wave Finite-Difference Numerical Simulation in Strongly Heterogeneous Media Using the Adaptive Mesh Refinement (AMR) Technique

Geophysics ◽  
2021 ◽  
pp. 1-76
Author(s):  
Chunli Zhang ◽  
Wei Zhang
Keyword(s):  
Finite Difference ◽  
Acoustic Wave ◽  
Adaptive Mesh Refinement ◽  
Heterogeneous Media ◽  
Mesh Refinement ◽  
Adaptive Mesh ◽  
Grid Spacing ◽  
Time Step ◽  
Velocity Models ◽  
The Stability

The finite-difference method (FDM) is one of the most popular numerical methods to simulate seismic wave propagation in complex velocity models. If a uniform grid is applied in the FDM for heterogeneous models, the grid spacing is determined by the global minimum velocity to suppress dispersion and dissipation errors in the numerical scheme, resulting in spatial oversampling in higher-velocity zones. Then, the small grid spacing dictates a small time step due to the stability condition of explicit numerical schemes. The spatial oversampling and reduced time step will cause unnecessarily inefficient use of memory and computational resources in simulations for strongly heterogeneous media. To overcome this problem, we propose to use the adaptive mesh refinement (AMR) technique in the FDM to flexibly adjust the grid spacing following velocity variations. AMR is rarely utilized in acoustic wave simulations with the FDM due to the increased complexity of implementation, including its data management, grid generation and computational load balancing on high-performance computing platforms. We implement AMR for 2D acoustic wave simulation in strongly heterogeneous media based on the patch approach with the FDM. The AMR grid can be automatically generated for given velocity models. To simplify the implementation, we employ a well-developed AMR framework, AMReX, to carry out the complex grid management. Numerical tests demonstrate the stability, accuracy level and efficiency of the AMR scheme. The computation time is approximately proportional to the number of grid points, and the overhead due to the wavefield exchange and data structure is small.

An adaptive mesh refinement algorithm for compressible two-phase flow in porous media

2011 ◽  
Vol 16 (3) ◽  
pp. 577-592 ◽  
Author(s):  
George Shu Heng Pau ◽  
John B. Bell ◽  
Ann S. Almgren ◽  
Kirsten M. Fagnan ◽  
Michael J. Lijewski
Keyword(s):  
Porous Media ◽  
Adaptive Mesh Refinement ◽  
Two Phase Flow ◽  
Mesh Refinement ◽  
Adaptive Mesh ◽  
Flow In Porous Media ◽  
Phase Flow ◽  
Two Phase ◽  
Refinement Algorithm

scholarly journals Adaptive Mesh Refinement Strategies for a Novel Modelof Immiscible Fluid Flow in Fractures

2021 ◽  
Author(s):  
Sobhan Hatami ◽  
Stuart Walsh
Keyword(s):  
Adaptive Mesh Refinement ◽  
Mesh Refinement ◽  
Adaptive Mesh ◽  
Uniform Grid ◽  
Immiscible Fluid ◽  
Multiphase Model ◽  
Front Tracking Method ◽  
Lattice Boltzmann Simulations ◽  
Refined Meshes ◽  
Flow Through

In this paper, we consider two Adaptive Mesh Refinement (AMR) methods to simulate flow through fractures using a novel multiphase model. The approach represents the fluid using a two-dimensional parallel-plate model that employs techniques adapted from lattice-Boltzmann simulations to track the fluid interface. Here, we discuss different mesh refinement strategies for the model and compare their performance to that of a uniform grid. Results from the simulations are demonstrated showing excellent agreement between the model and analytical solutions for both unrefined and refined meshes. We also present results from the study that illustrate the behavior of the AMR front-tracking method. The AMR model is able to accurately track the interfacial properties in cases where uniform fine meshes would significantly increase the simulation cost.The ability of the model to dynamically refine the domain is demonstrated by presenting the results from an example with evolving interfaces.

Computational Investigation of the Effects of Piston Geometry on the Combustion Evolution in a Light Duty HSDI Engine

2017 ◽  
Author(s):  
Riyaz Ismail ◽  
Felix Leach ◽  
Martin H. Davy ◽  
David Richardson ◽  
Brian Cooper
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Combustion Chamber ◽  
Adaptive Mesh Refinement ◽  
Fuel Injection ◽  
Temporal Distribution ◽  
Adaptive Mesh ◽  
Test Point ◽  
Piston Bowl ◽  
Dynamics Simulations

The spatial and temporal distribution of fuel and air within the combustion chamber directly influences ignition, combustion and emissions formation in diesel engines. These fuel-air interactions are affected by details of the combustion chamber geometry and fuel injection parameters. This paper investigates the effects of piston bowl geometry and spray targeting on combustion behaviour in a single cylinder diesel engine. Closed cycle computational fluid dynamics simulations are performed on a sector mesh at various load points using the 3 Zones Extended Coherent Flame Model coupled with adaptive mesh refinement. The computational fluid dynamics model is validated experimentally at the baseline conditions at each test point after-which, parametric sweeps of bowl geometry, exhaust gas recirculation rate and nozzle tip protrusion are conducted. Results indicate that appropriately pairing fuel injection strategy and piston geometry is essential.

scholarly journals Tracking Fronts in One and Two-phase Incompressible Flows Using an Adaptive Mesh Refinement Approach

2009 ◽  
Vol 41 (2) ◽  
pp. 221-237
Author(s):  
Stephanie Delage-Santacreu ◽  
Stephane Vincent ◽  
Jean-Paul Caltagirone
Keyword(s):  
Adaptive Mesh Refinement ◽  
Incompressible Flows ◽  
Mesh Refinement ◽  
Adaptive Mesh ◽  
Two Phase

Large Eddy Simulation of a Turbulent Spray Burner Using Thickened Flame Model and Adaptive Mesh Refinement

2020 ◽  
Author(s):  
Aleksandra Rezchikova ◽  
Cédric Mehl ◽  
Scott Drennan ◽  
Olivier Colin
Keyword(s):  
Large Eddy Simulation ◽  
Adaptive Mesh Refinement ◽  
Mesh Refinement ◽  
Adaptive Mesh ◽  
Two Phase ◽  
Jet Flame ◽  
Eddy Simulation ◽  
Reduced Mechanism ◽  
Large Eddy ◽  
Turbulent Spray

Abstract The accurate simulation of two-phase flow combustion is crucial for the design of aeronautical combustion chambers. In order to gain insight into complex interactions between a flame, a flow, and a liquid phase, the present work addresses the combustion modeling for the Large Eddy Simulation (LES) of a turbulent spray jet flame. The Eulerian-Lagrangian framework is selected to represent the gaseous and liquid phases, respectively. Chemical processes are described by a reduced mechanism, and turbulent combustion is modeled by the Thickened Flame Model (TFM) coupled to the Adaptive Mesh Refinement (AMR). The TFM-AMR extension on the dispersed phase is successfully validated on a laminar spray flame configuration. Then, the modeling approach is evaluated on the academic turbulent spray burner, providing a good agreement with the experimental data.

Sign in / Sign up

Export Citation Format

Share Document