Date post: | 15-Aug-2015 |
Category: |
Technology |
Upload: | lccausp |
View: | 13 times |
Download: | 3 times |
Laboratory of Thermal and Environmental EngineeringCombustion Research Center
Large Eddy Simulations of
Ethanol Spray Combustion
Dr.-Ing. Flavio Cesar Cunha Galeazzo, [email protected]
Prof. Dr.-Ing. Guenther Carlos Krieger Filho
3. Workshop de High Perfomance Computing 17. April 2015
Laboratory of Thermal and Environmental EngineeringCombustion Research Center
Experimental setup
PhD of Newton K. Fukumasu (2010 - 2014)
Open burner derived from an automotive fuel injector and a swirler
Laser diagnostics (PDI, LIF e PIV)
3WHPC-LCCA Flavio Galeazzo 2
Laboratory of Thermal and Environmental EngineeringCombustion Research Center
100 Hz 250 Hz 400 Hz
Case Injection
frequency
Duty
cycle
Combustion pattern
ESF100 100 Hz 29% Long anchored flame
ESF250 250 Hz 43% Short anchored flame
ESF400 400 Hz 59% Lifted flame
Boundary conditions
Air flow 20 m3 / h
Ethanol flow 2 L / h
3WHPC-LCCA Flavio Galeazzo 3
Numerical setup
OpenFOAM 2.1.1
LES (Large Eddy Simulation)
Smagorinsky subgrid scale model (SSG)
Spray
Lagrangian particle tracking
Combustion model
Simple “mixed is burned” approach
Laboratory of Thermal and Environmental EngineeringCombustion Research Center
3WHPC-LCCA Flavio Galeazzo 4
Laboratory of Thermal and Environmental EngineeringCombustion Research Center
Grid 1 Grid 2
Number of elements 600 000 1.6 million
Grid sensitivity
Hexahedral elements
Two grids with different refinement
Cold flow
Better agreement with refined grid
Grid 2 was used for the LES simulations
3WHPC-LCCA Flavio Galeazzo 5
• Cold flow
• Mean axial velocity UX at the centerline
• Experiments
• RANS simulation using Reynolds-stress turbulence model
• LES using Smagorinky SSG
• The negative velocities indicate the recirculation zone created by the swirl flow
• Much better agreement with LES
Laboratory of Thermal and Environmental EngineeringCombustion Research Center
3WHPC-LCCA Flavio Galeazzo 6
• Combustion
• Axial velocity(m/s)
• Temperature (K)
Laboratory of Thermal and Environmental EngineeringCombustion Research Center
7
100 Hz 250 Hz 400 Hz
• Experiment chemiluminescence
• Mean temperature (K)
Laboratory of Thermal and Environmental EngineeringCombustion Research Center
8
Laboratory of Thermal and Environmental EngineeringCombustion Research Center
Computational resources
BlueGene/P – USP/Rice
42 racks, 128 CPUs, 512 computing cores each
4 GB per CPU
Proprietary interconnect
SGI Altix cluster – LETE
12 nodes, dual CPU, 8 computing cores each
24 GB per node / 12 GB per CPU
Infiniband interconnect
Problems using BG/P
Compilation of OpenFOAM in the BG/P
Need GCC compiler – can’t use native IBM XL compiler
Need shared libraries – complicated to setup in the BG/P
Run the OpenFOAMsimulation in the BG/P
Need aprox. 2.5 GB per grid partition
Can’t use all computing cores of each CPU
3WHPC-LCCA Flavio Galeazzo 9
Laboratory of Thermal and Environmental EngineeringCombustion Research Center
Performance comparison
BlueGene/P – USP/Rice
42 racks, 128 CPUs, 512 computing cores each
4 GB per CPU
Proprietary interconnect
SGI Altix cluster – LETE
12 nodes, dual CPU, 8 computing cores each
24 GB per node / 12 GB per CPU
Infiniband interconnect
SwirlFlameLETE/1/H1/les_onlyFlow – cold flow
Grid = 1.6 million elements
ModeNumber of
partitions
Simulation
time (s)
Computing
time (s)
Relative
time
Blue
Gene/PSMP 128 0,002 517 1
LETE openmpi 24 0,002 450 0,87
SwirlFlameLETE/1/H1/EPS250/les_fireFoam - combustion
Grid = 1.6 million elements
ModeNumber of
partitions
Simulation
time (s)
Computing
time (s)
Relative
time
Blue
Gene/PSMP 128 0,002 8423 1
Blue
Gene/PSMP 256 0,002 6077 0,72
Blue
Gene/PSMP 384 0,002 5892 0,70
3WHPC-LCCA Flavio Galeazzo 10
Laboratory of Thermal and Environmental EngineeringCombustion Research Center
Conclusions
Better agreement of LES results with the experimental data
More refined computational grids and longer simulation time are required for LES
For more refined grids there is a need of more computational power
OpenFOAM 2.1 was successfully compiled in the BlueGene/P
The performance is not ideal
Old GCC compiler (version 4.3.2, from 2008)
Memory usage of OpenFOAM do not permit the use of all computing cores
Use of OpenMP is an alternative
Current development, up to now no speedup using Paralution OpenMP solver
11
Laboratory of Thermal and Environmental EngineeringCombustion Research Center
Thank you
Dr.-Ing. Flavio Cesar Cunha Galeazzo, [email protected]
Prof. Dr.-Ing. Guenther Carlos Krieger Filho
12