Case Studies

PORT-INJECTED FUEL SPRAY AND VAPOR ISO-SURFACES
Livonia, MI - November 2003

Contributed by: Doug Baker, Ph.D. President TECAT Engineering, Inc.

Animated port-injected fuel spray and vapor iso-surfaces from a computational fluid dynamics (CFD) simulation. Advanced simulations, coupled with powerful pre- and post-processors, make rapid engine design, optimization, and prototyping possible. Click here to download the AVI movie (9,996 KB AVI)

The Engineer
Doug Baker is president of TECAT Engineering, Inc. located in Livonia, Michigan. TECAT designs, develops and tests reciprocating, internal combustion engines and software optimization tools. Their customers include the Department of Defense (Army/Navy), Department of Energy, National Renewable Energy Laboratories, and Ford Scientific Research Laboratories.

The Plot
The animation displays port-injected fuel spray and fuel vapor iso-surfaces during two thermodynamic cycles of a four-valve, pent roof, spark-ignited engine simulation. The movie illustrates:

• A blue, low fuel vapor concentration
• A brown, stoichiometric fuel vapor concentration
• A red, high fuel vapor concentration

The animation was generated by first outputting each simulation time-step as an individual zone in a Tecplot data file. (The TecIO library helps write Tecplot binary files directly from their simulation.) In Tecplot, a macro loops through each zone, changes the orientation, and exports the image to an .AVI movie file.

The Simulation
Results were generated with TECAT's WinKiva™ - a Windows-native, CFD, internal combustion engine simulator. The solution required approximately ten processing hours on a 2.0GHz Pentium 4 desktop computer.

WinKiva™ (based on Kiva-3VR2 developed at Los Alamos National Laboratories) models the transport of mass, energy and momentum within internal combustion engines. It simulates fuel particle injection, droplet break-up, coalescence, chemical conversion, as well as impingement and evaporation in valves, ports and manifolds. The solver predicts a wide variety of thermodynamic properties for each computational cell including pressure, temperature, density, velocity fields, and turbulent kinetic energy. WinKiva™ also models chemical properties such as species concentrations, reaction rates, and the formation of regulated emissions.

Tecplot
Doug uses Tecplot to examine his simulation results which help evaluate and improve engine design. He says, "Using Tecplot we rapidly analyze our solutions. Data is presented in such a compact way we observe trends that otherwise may not be obvious. This enables us to optimize engine designs in a fraction of the time."

Doug goes on to say, "Tecplot provides tremendous productivity gains and reduces data manipulation errors. In some of our cases we interactively visualize results while simulations are underway. This offers early detection of solution abnormalities and is a huge improvement over visualizing results after a simulation is complete."

Screen shot of TECAT's Virtual Dynomometer Engine Simulation (VDES) Software. VDES is an interactive simulation tool that uses Tecplot for its GUI and real-time visualization. Users input changes on-the-fly, such as design variables and operating conditions, and instantly visualize their impact on individual cylinder and system performance. Users can also open, edit, and close multiple plots during simulation runs.

Typically Doug uses Tecplot to visualize 3-D internal combustion engine reciprocators and porting solutions. Using quasi-dimensional cycle simulations, he generates a significant number of both 2- and 3-D engine system performance plots including: turbo machinery map characteristics, fuel economy maps, system pressures and temperatures, system power and torque, transient emissions and thermal characteristics. His plots often include iso-surfaces, streamtraces, scatter particles, value-blanking, contouring, and vector plotting.

Prior to Tecplot, Doug says he was unable to effectively analyze huge amount of information generated from their simulation tools. "We previously used WinK3Post for plotting multi-dimensional CFD results, and KaleidaGraph and Excel for 2-dimensional plots. These tools were relatively time-intensive to use, and offered minimal flexibility for visualizing our data. They also required significant manipulation of the data...Tecplot has provided significant cost-savings over these tools."

Tecplot Tips

1. The easiest way to build macros is to use the Macro Record feature, then edit unwanted steps in a text editor. This capability is a huge time saver. Take it one step further and utilize the Quick Macro Panel (QMP) to access commonly used macros in one click. Analyze your operations and identify repetitive tasks. Create macros that perform these operations and place them on the QMP.
2. Customize your animations exactly the way you want with Tecplot.

• Activate or deactivate multiple zones for each movie frame.
• Define rotation angles prior to exporting movies.
• Loop and skip zones to produce smaller AVI file sizes.
• Overlay different plot types and zones. (For example, overlay 3-D fuel particle scatter symbols with no connectivity on top of 3-D fuel vapor iso-surfaces with connectivity.)

1. Combine Tecplot's GUI building, macro, and TecUtill function capabilities to create a complete pre- and post-processing solution interface for your simulations.

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