Introduction

• Pneumatic system:
  • turbulent flow of a compressible medium
  • large pipe network
  • highly non-linear components (eg actuators, valves)
• Modeling approaches for components:
  • PDE-based (CFD)
  • 1d/2d coarse grained finite volume (special Modelica libraries)
  • 0d = simple ODE or algebraic equation (standard Modelica library MFL)
• Modeling of large networks:
  • using MFL is cumbersome (Drente, Junglas 2015)
    • large system of nonlinear equations
    • initialisation problem is still unsolved (here)
    • tee branches particularly difficult
    • models only run after drastic simplifications
  • DLR ThermoFluidStream Library TFS (Zimmer et al. 2022)
    • generally assumes fixed flow direction
    • adds inertial pressure of fluid → mass flows become state variables
    • clever approximation scheme decouples components
    • leads to linear or small non-linear equations → initialisation often works
    • suitable approach for pneumatic pipe networks?