A high-fidelity real-time simulation code based on a lumped, nonlinear representation of gas turbine components is presented. The code is a general-purpose simulation software environment useful for setting up and testing control equipments. The mathematical model and the numerical procedure are specially developed in order to efficiently solve the set of algebraic and ordinary differential equations that describe the dynamic behavior of gas turbine engines. For high-fidelity purposes, the mathematical model takes into account the actual composition of the working gases and the variation of the specific heats with the temperature, including a stage-by-stage model of the air-cooled expansion. The paper presents the model and the adopted solver procedure. The code, developed in Matlab-Simulink using an object-oriented approach, is flexible and can be easily adapted to any kind of plant configuration. Simulation tests of the transients after load rejection have been carried out for a single-shaft heavy-duty gas turbine and a double-shaft aero-derivative industrial engine. Time plots of the main variables that describe the gas turbine dynamic behavior are shown and the results regarding the computational time per time step are discussed.

This paper provides an innovative technique for the control of a variable-geometry turbine in a turbocharged compression ignition engine. Such a control algorithm is based on a multi-agent System scheme. It is seldom that agents are considered as stand-alone systems; on the contrary, their main strength can be found in the interaction with other agents, constituting the so-called multi-agent System. An agent is a software or hardware entity that can receive signals from the environment and act upon that environment through output signals, trying to carry out an appropriate task. In the present paper, a fuzzy logic system has been employed for the agents' internal structure. In order to test the performance of the proposed control technique, a numerical model of the engine has been used, which employs a thermodynamic (zero-dimensional) approach. The paper will show that the proposed control technique is able to take into account the non-linearity of the controlled system.

In modern gas turbines in which lean premixed flames are used to obtain low NOx emissions, large pressure oscillations may arise inside the combustor due to thermoacoustic combustion instability at frequencies corresponding to the natural acoustic frequency of the system. Such pressure fluctuations, that may cause structural damages, need to be damped in order to avoid a reduction of the operational range of the gas turbine. In this work Helmholtz resonators connected to the external envelope of the combustion chamber are examined as passive systems for damping the low frequency acoustic pressure in the case of an annular combustor. The acoustical behavior of the combustor has been first investigated by means of the Finite Element method, obtaining its acoustic eigenmodes and eigenfrequencies in order to tune the Helmholtz resonators on the frequency to be damped. In order to characterize the resonator, preliminary tests have been carried out on a simplified system composed of a Helmholtz resonator applied at the end of an impedance tube. Then the eigenmodes of the system obtained by connecting one or more resonators to the annular chamber and the damping effects obtained by varying the geometry, the number and the position of the resonators are analyzed. It appears that the peak of acoustic pressure characterizing the combustion chamber splits into two peaks of lower magnitude when the Helmholtz resonators are applied and the peak frequencies are correlated to the overall volume of resonant cavities, whilst lower effects are obtained by varying the position and the number of resonator units.

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In recent years the idea of artificial intelligence has been focused around the concept of rational agent. An agent is an (software or hardware) entity that can receive signals from the environment and act upon that environment through output signals, trying to carry out an appropriate task. Seldom agents are considered as stand-alone systems; on the contrary, their main strength can be found in the interaction with other agents, constituting the so-called multiagent system. In the present work, a multiagent system was chosen as a control system of a single-shaft heavy-duty gas turbine in the multi input multi output mode. The shaft rotational speed (power frequency) and stack temperature (related to the overall gas turbine efficiency) represent the controlled variables; on the other hand, the fuel mass flow (VCE) and the variable inlet guide vanes (VIGV) have been chosen as manipulating variables. The results show that the multiagent approach to the control problem effectively counteracts the load reduction (including the load rejection condition) with limited overshoot in the controlled variables (as other control algorithms do) while showing a good level of adaptivity, readiness, precision, robustness, and stability.