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AutoReaGas is specially designed software for modeling gas explosions and their consequences, extensively validated and at an affordable price through a range of short and long term licensing options – the cost-effective validated software for gas explosion modeling.
Specially for Congested and Confined (Open and Closed) Environments
AutoReaGas is a CFD based software which is specially designed for modeling
gas explosions and their effects in congested and confined environments. Congestion is provided by equipment such as pipework while confinement is provided by structures such as blast walls and buildings. Solid walls (closed), partially vented (blow-out panels) and fully vented (open) environments can be defined and thus the software is suited to scenarios which can exist in both offshore and onshore facilities.
The AutoReaGas software includes an easy-to-use integrated solid model object database – a simplified CAD system – to enable the detailed geometry to be represented. Geometry can be imported from third party CAD based plant design software or generated using the integrated features. Geometry typically comprises cylinders (pipes and equipment), boxes (equipment and buildings) and planes (blast walls, blow-out panels, decks and gratings each of which can have associated porosity).
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Often at early stages of a project (say in FEED for example) where only limited geometry is defined, the available geometry can be imported while the anticipated further geometry can be defined directly – thus allowing a reasonable estimate of the gas explosion consequences at the earliest stage. Both of the above models have been generated through a combination of PDMS geometry import with additional geometry defined within AutoReaGas.
Fully 3D Analysis – modeling influences of 3D geometry, cloud and ignition position
AutoReaGas conducts a fully 3 dimensional (3D) analysis to represent a genuinely 3D scenario. That is to say it uses a 3D geometry, a 3D gas cloud shape (and composition as required) and treats ignition points at any location within the gas cloud.
As indicated above, AutoReaGas uses a fully 3D geometry to represent a given facility. An important feature of the software is the usage of a subgrid
modeling technique to represent the effects of small objects (smaller than a mesh dimension in the numerical model) to be adequately represented. These are objects are automatically translated into the mesh to ensure that they are included in the calculation and adequately represent the resultant flame acceleration. The (simple) geometry below shows an offshore platform complex (left) that was generated all from within the AutoReaGas software. The small (subgrid) objects from the largest (production) platform are shown on the right plot.
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The explosion scenario – comprising the gas cloud (and its composition) and the ignition location – can also be represented in 3D. As shown on the right, gas clouds can be of arbitrary shape (and also composition) and can be ignited at any point of the cloud. |
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Explosion and Blast Solvers – the right solver for efficiently capturing the right phenomena
Within and local to an ignited gas cloud, the major influence on the consequences (overpressure, impulse etc) is the flame acceleration resulting from turbulence in the flame front caused by equipment in the flowfield. Both laminar and turbulent combustion models are included to allow the effect of flame acceleration to be represented in the Gas Explosion Solver (Navier-Stokes based) within the 3D geometry (including subgrid geometry), gas cloud location and selected ignition point.
A gas explosion generates a blast wave that propagates to the far field where it interacts with other structures. Importantly, such a far field blast wave is not significantly influenced by the effects of small objects like pipes. Thus, AutoReaGas has a Blast Solver (Euler based) which is specifically designed to quickly and accurately calculate the propagation of such blast waves and – importantly the results of the Gas Explosion Solver are automatically transferred to the Blast Solver to ensure that the blast propagation calculation is started from a representative blast field.
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The above left plot shows overpressure contours calculated in the Gas Explosion Solver while the right plot shows the “remapped” blast field in the Blast Solver. The 2 plots below show the propagation of the blast wave into the far field including the reflection and diffraction around adjacent platforms.
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Validation – small, medium and large scale gas explosions
AutoReaGas is extensively validated against various small, medium and large scale experiments.
Initially, small and medium-scaled experiments were conducted as part of the fundamental research into understanding the effects of gas explosions and to assist in developing numerical models. Century Dynamics Ltd. partner in the development of AutoReaGas, TNO, were pioneers in such research in both experimental and numerical model developments. For example, they conducted the small scale FAST experiments which looked at the effects of obstacle shape and configuration on the resultant flame propagation in a non-diverging flow field. They also lead the European Commission funded research projects entitled MERGE and EMERGE which incorporated up to medium scale experiments. Below is a typical test (left), the geometry which comprised a series of orthogonal pipes as defined in AutoReaGas (middle) and the resultant calculated overpressures (right).
  
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Ultimately, the key to any simulation software is the demonstrable quality of the results at full scale, which is particularly important for explosion models. The industry benchmark for the validation of a gas explosion model remains the work conducted under the Phase 2 of the joint industry project “Blast and Fire Engineering for Topside Structures” (BFETS).
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As shown below, AutoReaGas performed well in this project.
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Water Deluge – influence on consequences
The aim of water deluge is to reduce the reaction rate of a gas explosion and thus limit the flame speed and the pressure build-up. Its advantages are that in many cases the deluge system is already in place for fire protection purposes, that the supply of water on an offshore platform is practically endless and that water is safe for use both to personnel and to the environment.
Different regions can be defined to have deluge. For example, the plots below show 2 separate regions of deluge (left) and a single large deluge region (right).
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For the above (right) case with an ignition point at the center of the left end, the plot to the right shows the close comparison between test and simulation. It is also observed that the peak overpressure with deluge was reduced to approximately 10% of the overpressure observed with no deluge. |
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Interface to Structural Analysis Software – it is the structure you are designing after all!
Gas explosion modeling is not done in isolation – although it may form a particular part of a Safety Case or risk assessment study – as the other important complementary
modeling requirement is that associated with the structural design. AutoReaGas results can be readily exported to structural analysis software such as our AUTODYN and ASAS structural analysis software.
Time History Export
Time histories of any calculated or user defined variables can be plotted inside the AutoReaGas user interface. They can also be exported as ASCII files for reporting or subsequent usage. For example, a series of pressure-time histories may be output and translated into the necessary load curves for a structural analysis software (such as AUTODYN and ASAS).
Remap to AUTODYN-3D – for coupled blast-structure interaction
It is often important to consider the effects of reflection and diffraction of the blast waves on and around objects including the influence of structural deformation.
In AutoReaGas, it is possible to save the current state of the gas in an explosion/blast analysis and import this data directly into the AUTODYN-3D software. In AUTODYN, it is possible to conduct more extensive blast analysis but importantly including the effects of coupled blast-structure interaction. This is illustrated below by a simple example of the blast loading and response of a cubical structure.
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The AutoReaGas solution (top left) can be mapped into an AUTODYN-3D FCT grid (top right) where the pressure wave can fully interact with a deformable solid object though the use FCT-Lagrange coupling. The final shape of the deformable object can be seen bottom left. |
Licensing Tailored to Project and User Requirements
Gas explosion safety studies are often carried out on a project-by-project basis, while on other occasions they are conducted as a routine part of an
organization's engineering safety procedures.
In order to meet these differing needs, a number of tailored licensing options are available. For those with short term or project oriented requirements, short terms leases of 3 or 6 months duration are also available. For those users with regular or strategic requirements, long term licenses are also available. These include Paid-Up (perpetual) License and Annual License options.
After the purchase of an initial license, it is possible to tailor additional licenses to meet your needs. Options exist to allow further “Full Software” licenses to be obtained or “Solver Only” and “Pre- and Post-Processing Only” licenses.
These flexible and favorably priced licensing options mean you can choose the right type of license to meet your specific needs.
