Cryogenic jets atomisation

MODELLING THERMAL AND SPRAY CHARACTERISTICS

The prediction of the spray dynamics and dispersion is of critical importance to predict the behaviour of the vapour cloud that cryogenic liquids produce, and is now part of an upheaval in the global energy industries for generating numerical tools to model the process. Important features of pressurised jets of cryogenic liquids can be predicted using the capabilities of cryoFoam.

FLASH-BOILING AND CAVITATING JETS

Flashing jets occur when a high-pressure liquid flowing through a nozzle or an orifice is suddenly exposed to a low-pressure environment, becoming superheated if it is not already so. Flashing is characterised by a rapid phase change along the jet and bubble nucleation within the liquid core that influences the spray formation .

Flashing is very important in safety studies in cases of accidental releases of a liquefied flammable gas through a small crack in the pipeline system. In the aerosol industry it can be used to control nucleation having the advantage of producing sprays with very fine droplets within small domains. In its dense part, the two-phase jet might appear in different forms like bubbly, slug or annular and the nucleation is possible to start upstream of the orifice (a process generally termed internal flashing) or at some distance downstream of the orifice (external flashing). The geometry and the nozzle length-to-diameter ratio, the degree of superheat or sub-cooling, the storage and ambient conditions play a crucial role in the atomisation process. Flashing occurs either if a liquid follows an isothermal depressurisation or an isobaric heating. In both cases, the fluid fails to adjust to the local changes in pressure and temperature admitting a metastable state which makes the process more challenging to understand.

 

COMPUTATIONAL FLUID DYNAMICS (CFD)

Computational fluid dynamics (CFD) is the art of solving the equations that govern physical phenomena using computers. CFD can give accurate predictions and provide solutions that do not suffer from empiricity, giving a detailed representation of the physics underpinning a process.

Quality, customability and flexibility

  • Open source software gets the closest to the processes’ needs because we can tailor and modify the software according to any specific needs.
  • No more CFD black boxes. Remember that CFD means programming and applying models, a limited or missing option in commercial software.
  • This means that the developers have access to the code and can provide high quality solutions dedicated to the client.

No licence, No extra charges

  • There is no need for the developers to pay for a license, a saving that can be passed onto the client.

OpenFOAM toolbox

The underlying framework for our simulations is the open source software OpenFOAM. The software established nearly 20 years ago offers a vast variety of solvers for industrial applications. Having an ongoing users community that supports and develops OpenFOAM, it is one of the most popular, trustable CFD software in the market offering many advantages for high performance and massively parallel computing. Additionally, Salome is used for mesh generation offering a cad-based platform with numerous capabilities for very complex geometries.
Paraview is one of the few post processing tools we use. Provided by Sandia laboratories, it has been used in academia and industry for data analysing and is also open source.