Ph.D. received on: 8/7/1997

E-mail: mattei@disna.dis.unina.it

Tutor: Prof.  Giuseppe Ambrosino, Dipartimento di Informatica e Sistemistica, Università di Napoli Federico II
 
 

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Modeling and control of a plasma wind tunnel   ___________________________________________________________________________________________________________

Advisor:

Prof. Giuseppe Ambrosino, Dipartimento di Informatica e Sistemistica, Università di Napoli Federico II

Summary:

The 70MW Scirocco Plasma Wind Tunnel under construction at CIRA (Italian Aerospace Research Center) is a modern, arc heated, plasma wind tunnel capable to reproduce, on suitable test articles, the thermal stress conditions to which some parts of capsules or space vehicles are subjected during the re-entry in atmosphere. The thesis is essentially oriented to the development of a dynamic model of the plant and to the synthesis of the test control algorithms to be implemented in the Central Control System. As far as the modeling of the plant is concerned, some simplifying hypotheses are proposed in order to build a flexible tool oriented to the control system design. The complex aerothermodynamic processes occurring during the wind tunnel operations, usually described by the Navier-Stokes/Heat partial differential equations, are modeled by means of an hybrid ordinary differential equations-neural network model. As for the control problem it is a classical trajectory following problem: the objective is to reproduced desired time trajectories of temperature and pressure on the test model. The controlled variables are the electric arc current and the mass flow rate to the arc heater. The proposed control scheme consists of two terms: a feedforward action, calculated off-line via a receding horizon technique using the above mentioned plant model, which guarantees the tracking of the desired output trajectory in absence of modeling errors, and a gain scheduled discrete time output feedback control action to counteract possible misalignments between the desired trajectory and the actual one. In the thesis also the problem of controlling the air compressed supply system and the power supply system is considered. Finally the particular application discussed is the occasion for methodological digressions on robust control of linear parameter varying systems. In particular e new technique to check stability of a discrete time system depending on uncertain slowly-varying parameters is presented.
 

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