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The design of modular dynamical fluid simulation systems
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
2005 (English)Conference paper, Published paper (Refereed)
Abstract [en]

The objective of this paper is to give an overview of methods for simulation of dynamical fluid systems. Typical applications for such simulations are the design of pneumatic and hydraulic systems, internal combustion engines, cooling systems, and air management systems for fuel cells. The governing Navier-Stokes equations are presented and from them the one-dimensional lumped governing equations are derived. Different methods for solving systems of interconnected components are presented: the state-space/bond-graph method, transmission line modelling, and CFD (Computational Fluid Dynamics) methods. Finally a method to solve the problems using the fully dynamical equations is presented. The method is to use the bond-graph method to systemise the system, and then add virtual mass to the dynamical equation in order to make the simulation system faster to solve. Results from the verification of this are presented in the results section of this paper.

Place, publisher, year, edition, pages
2005. 1-12 p.
Keyword [en]
air management, modular simulation, dynamic systems, simulation-based design
National Category
Computer Science
Identifiers
URN: urn:nbn:se:kth:diva-27723OAI: oai:DiVA.org:kth-27723DiVA: diva2:380231
Conference
Proceedings from the OST Conference, KTH Machine Design, Stockholm, Sweden, 2005
Note
QC 20101221Available from: 2010-12-21 Created: 2010-12-21 Last updated: 2010-12-21Bibliographically approved
In thesis
1. On the modular modelling for dynamical simulation with application to fluid systems
Open this publication in new window or tab >>On the modular modelling for dynamical simulation with application to fluid systems
2005 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

This licentiate thesis highlights some topics on modular modelling for dynamical simulation with application to fluid systems. The results are based on experience from the development of the fuel cell component simulation environment NFCCPP. The general application is cross-enterprise simulation of technical systems. There are four main topics: component definition including selection of interfaces, lumped modelling of fluid components, the use of dynamical equations to reduce simulation time in large systems and methods of to protect the intellectual property (IP) of a component.

An overview of different dynamical fluid simulation tools such as HOPSAN, MATLAB/Simulink and Easy5 is presented. Special focus is on interfaces, where different approaches for representing interfaces are presented using an illustrative example. Selecting interfaces is however not a separated task from how to set up and solve the underlying equations, which also is shown. Equations to model a lumped component are derived, to get a mathematical background to what problems there are to solve. These equations are derived especially to be applicable in block model software simulation tools such as MATLAB/Simulink. The equations are also compared with the bond-graph approach of representing dynamical systems. A twinscrew compressor is modelled in MATLAB/Simulink as an implementation of these equations. A method to decrease the simulation time in dynamical fluid system is also presented. The technique is to add virtual mass in the force equation to get a slower acceleration of the fluid. Using this slower response, it is possible to use larger time-steps when integrating the equations and thus the total simulation time can be reduced. The error introduced using this method is a modelling error in the time domain, and it is comparable with using unit transmission lines (UTL:s), as does HOPSAN.

The protection of the intellectual property (IP) of a component model is presented. The concept of clamping is thoroughly explained, as it often is overlooked in conventional IPprotection. Three concepts for code protection are presented: “Centralised simulation with remote user control”, “Localised simulation with simulation-time model usage control” and “Parallel distributed simulation”. The NFCCPP implementation of the concept “Localised simulation with simulation-time model usage control” is presented in more detail.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. viii, 20 p.
Series
Trita-MMK, ISSN 1400-1179 ; 2005:30
National Category
Computer Science
Identifiers
urn:nbn:se:kth:diva-566 (URN)
Presentation
2005-12-06, sal A425, KTH, Brinellvägen 83, Stockholm, 10:00
Opponent
Supervisors
Note
QC 20101221Available from: 2005-12-28 Created: 2005-12-28 Last updated: 2010-12-21Bibliographically approved

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CiteExportLink to record
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