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I read in a newspaper that we will manage the five degree maximum limit of global temperature increase but fail on the two degree target, if all countries keep their current promises. Even the five degree limit requires not only energy savings but also demands finding ways to increase efficiency, switching to renewable fuels and improving exhaust cleaning techniques to properly remove NOx. Lately, the challenge of keeping high efficiency while simultaneously reducing NOx emissions has received a lot of attention in the automotive industry.

As a consequence, the activity in R&D of biofuel technology has risen over the past few years for automotive and aerospace combustion engines, among others. This poses new technology challenges due to the different chemical composition of these fuels, yielding new demands on the development and research, and thus also on combustion simulation for these fuels. We strive to make this work easier for you through improving the integration of the fuel chemistry modeling with combustion CFD calculations. DARS v2.12 is one step in this direction. The aim of this release is to make your R&D work more productive through easier and faster building of complex chemistry-based combustion libraries.*

We have focused on efficiency, robustness, and workflow for this release:

  1. Efficiency: We have simplified the licensing scheme by removing the HPC licenses. Therefore, you can now generate a combustion library for STAR-CD or STAR-CCM+, or run a multirun on any number of cores using only one DARS license. Through the command line functionality developed for 2.10, a full cluster can be used to generate combustion libraries fast and efficiently.
  2. Robustness: We care about your efficacy and try to remove your sources of annoyance. Therefore, we focused the last development cycle on stabilization and testing. As a result of this, we have identified, resolved and improved many minor problems and features.

Figure 1: Calculate your multiruns or libraries on as many cores as you have access to, without caring for HPC licenses.

  1. The workflow for in-cylinder combustion calculations is improved:

    • The ECFM-CLEH libraries produced by DARS v2.12 can be used directly in STAR-CD, without any intermediate steps required. The PDF integration step required for import in STAR-CD is now made directly in DARS.
    • Libraries where not all points converged can be used directly in STAR-CD, removing the need to re-calculate individual missing points. Linear interpolation / extrapolation is used to automatically fill in missing points in ECFM-TKI or ECFM-CLEH libraries. As a result, even libraries with some points missing can be used directly in STAR-CD, saving a lot of engineering time.


Figure 2 : The workflow for in-cylinder combustion simulations has been improved. Build the library in DARS, import it directly in STAR-CD.

  1. The workflow for laminar flame speed calculations for advanced fuel chemistries has also been improved. Earlier you had to use a separate executable for calculating laminar flame speeds with chemical mechanism larger than 795 species and 6,000 reactions. DARS v2.12 automatically detects the size of the mechanism and chooses the executable, enabling straightforward calculations for up to 1,400 species and 10,000 reactions

All in all, the steps mentioned above are all on the path to more efficient and effective chemistry simulations. And this is just one step forward, as the work continues for the next release.

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* A complex chemistry based combustion library is information from calculations with a detailed chemical mechanism stored in tabular form. Such a library can be used in CFD for a few independent variables such as fuel mixture fraction and progress variable, instead of transporting all species and solving all reactions on the fly. Thus it is much more efficient than online chemistry.

 

Matthew Godo's picture
Matthew Godo
STAR-CCM+ Product Manager
Stephen Ferguson's picture
Stephen Ferguson
Marketing Director
James Clement's picture
James Clement
STAR-CCM+ Product Manager
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Dr Mesh
Meshing Guru
Joel Davison's picture
Joel Davison
Lead Product Manager, STAR-CCM+
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Ravindra Aglave
Director - Chemical Processing
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Sabine Goodwin
Director, Product Marketing
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Karin Frojd