In the early phase of a thermal-fluid system design process, the geometry has yet to be defined (complete 3D solid model of the flow path geometry is not available). In this design phase a flexible method of varying the geometry and elements of the thermal-fluid system is very useful for estimation of leakage, cooling or bleed air flow parameters for different fluid path sections while taking into account heat exchange of cooling flow with metal surfaces.


Some Examples of Applications:
  • Gas turbine secondary air systems
  • Gas turbine blade cooling systems
  • Steam turbine secondary flow systems (including gland seal leakages)
  • Industrial gas systems
  • Ventilation systems
  • Other thermal-fluid systems

AxSTREAM® NET is 1D system modeling solver based on finite volume method that uses a thermal-fluid network approach to simulate secondary flows and heat transfer at steady and unsteady (transient) conditions. The non-necessity for 3D geometry allows for its use before finalizing the blades geometry while keeping a good accuracy in the results in a very short computation time. This helps considerably reduce the iterations time required to optimize aerodynamic cooling losses and machine performances.


Scope of Work

This flexible tool allows creating an infinite number of systems and sub-systems of solid structures, convection components and fluid path elements through drag and drop from library of embedded components and possibility for users to incorporate their own elements and formulations.


Individual flow path components and full flow path (for example, turbine and compressor) can be modeled. For each fluid path section (represented by the appropriate element(s)), the program calculates fluid flow parameters for inlet and outlet cross-sections, like velocity, pressure, density, temperature, mass flow rate, total parameters, as well as pressure loss, convection, conduction, heat transfer coefficient, etc.

System Components

Element libraries include not only basic components like pipes, ducts, walls/bodies and orifices but also special components (labyrinth seals, rotor-stator cavities, rotating annular gaps and others) to model complex turbine secondary flow systems, including different convection formulations. The computations also take into account rotating and stationary surface elements, changing cross section areas of ducts, flow bends, air heating, fluid mixing and splitting, and other features while allowing for swirl to be omitted, user-defined (based on rotation axis, speed and radial location) or transferred between consecutive components.

  • Ideal gases
  • Integration of NIST RefProp fluids, including steam
  • Customized mixtures
  • Applicable to compressible and incompressible fluids

For enhanced flexibility and automation, extensive scripting capabilities (C# language) exist in AxSTREAM® to calculate properties based on user-defined subroutines. Data exchange between AxSTREAM NET and other software enables a tight integration useful to perform multi-run calculations as well as multi-disciplinary batch mode optimization tasks.

Sectors concerned include:
  • Industrial
  • Mining
  • Refrigeration
  • Process design
  • Defense
  • Appliances
  • Hydraulic equipment
  • Ventilation
  • Fossil fuel
  • Nuclear
  • Oil and gas
  • Space propulsion
  • Turbomachinery design