Distribution parametric pneumatics

 

In the age of digitalization, simulation models play a central role. For the design or condition monitoring of complex systems, accurate time-efficient numerical computational models are needed. The aim of the research project is to develop a simulation library for the time-efficient calculation of gas-powered networks. In doing so, the components are resolved in one or two dimensions in order to be able to accurately represent transient phenomena.

 
Benefit Procedure
Simulate pneumatic systems Create finite element volume models
Design pneumatic systems Design in openModellica
Modular simulation of locally resolved components Experimental validation

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Design of pneumatic systems by means of efficient simulation

Simulations are an important, cost- and time-saving tool for the development and design of pneumatic systems. The complexity of modern pneumatic systems no longer allows a purely analytical evaluation. In principle, it is possible to map a pneumatic system by means of a complete simulation and the methods of modern computational fluid dynamics, such as the finite element method. However, this involves a large amount of computation and time.
For this reason, complex pneumatic systems are usually designed using a 0-dimensional simulation, in which each component is described by its own ordinary differential equation.
However, these models quickly reach their limits when it comes to designing highly dynamic systems with long lines and high clock frequencies.

 

Novel simulation model

The goal of this project is to develop a novel simulation model that represents a compromise between high accuracy computational fluid dynamics (CFD) methods and fast 0D simulations. It should be able to simulate transient pneumatic systems without significant loss of accuracy. These simulations should not take significantly longer than the simulated time.
For this purpose, a simulation model is being developed in this project, in which a pneumatic system can be assembled from various components. However, these components should not be described by a single equation, but should be resolved locally in one or two dimensions. Thus they have to be described by a partial differential equation. The system is then calculated using the finite volume method, with recourse to the exact analytical solution for individual components, if this is known.

 

Modular structure

Copyright: © ifas

The implementation of the model takes place in the Modelica modeling language. A large number of different implementations of Modelica exist, including the free software OpenModelica. Modelica allows the end user to assemble a simulation model from various components that can be taken from a pre-built library. Such a library will be developed in this project. Complex components can be assembled from primitive components.

In particular, the following components for the library will be implemented in this project:

  • Elastic tube
  • Sudden change of the tube cross section
  • Realistic valve geometry
 

Experimental and simulative validation

Copyright: © ifas

The newly developed components will be validated in two different ways during this project.

On the one hand, preliminary work at ifas on other simulation models can be used to validate the new simulated components.

On the other hand, a test bench is being built at ifas, which can be used to experimentally validate individual components as well as simple pneumatic systems. For this purpose, high-precision piezoelectric sensors are used to accurately measure rapid pressure fluctuations caused by pressure as well as dilution waves.

With the help of this test bench, the individual steps in the development of the simulation model can be checked and in the later course of the project it can be shown how accurately and how quickly it can describe transient pneumatic events in realistic pneumatic systems.

 

Acknowledgement

Copyright: © VDMA

The project is accompanied and supported by an industry-dominated working group of the Research Fund of the Fluid Power Association in the VDMA. The authors would like to thank all those involved for their financial support and technical assistance.