Aerospace Science and Technology 15 (2011) 183–192 Contents lists available at ScienceDirect Aerospace Science and Technology www.elsevier.com/locate/aescte Tuning of fuzzy fuel controller for aero-engine thrust regulation and safety considerations using genetic algorithm Morteza Montazeri-Gh ∗ , Amir Safari System Simulation and Control Laboratory, Department of Mechanical Engineering, Iran University of Science and Technology, Tehran, Iran article info abstract Article history: Received 18 July 2008 Received in revised form 9 September 2010 Accepted 15 October 2010 Available online 21 October 2010 Keywords: Gas turbine aero-engine Fuel control system Fuzzy logic Genetic algorithm Previous studies have demonstrated that fuzzy logic control (FLC) could be applied to the design of the gas turbine aero-engine (GTE) fuel control system. However, due to the complex nature of the gas turbine aero-engine, FLC design based on the engineering intuition frequently fail to achieve satisfactory overall system efficiency and therefore an intelligent approach based on an optimization algorithm must be used. In this paper, a genetic-fuzzy control is employed in order to meet the engine performance requirement (thrust regulation) and constraints (safety considerations). In this approach, an initial FLC is firstly designed for the engine fuel system. Subsequently, the optimal tuning of the FLC parameters is performed based on the formulation of an optimization problem solved by a multi-objective genetic algorithm (GA). For this purpose, the objective functions are set to increase the GTE dynamic performance while obtaining the desired thrust and satisfying the safety constraints. A computer simulation program is also developed to investigate the effectiveness of the approach for a single spool jet engine. The simulation results are validated by the experimental data to support the simulation model. The results obtained from the simulation show the ability of the approach to achieve an acceptable thrust performance as well as the engine protection against the safety considerations such as engine over-speed, turbine over-temperature and the surge in compressor with sufficient safe margin. © 2010 Elsevier Masson SAS. All rights reserved. 1. Introduction Gas turbine aero-engine (GTE) has played a significant role in the expansion of the flight capabilities of modern aircrafts. For a GTE, stable and safe operation of the engine components must be ensured in order to operate at the operability and performance level for which it is designed. The thrust response is also of great importance for an aircraft, both in terms of the speed of response and accomplishment of the adequate thrust [17]. Hence, an appro- priate control system has always been an essential part of the GTEs to provide both regulation and management [18]. The main task of the control system for gas turbine aero-engine is the production of an adequate thrust (Thrust regulation) while maintaining safe and stable operation (Safety considerations) [16]. The safety considerations include the flow instability, high heat loads and high cyclic stresses. Development of the GTE control system requires a profound un- derstanding of the steady-state and transient behaviors of the GTE. As the engine fuel flow has a very important impact on the en- gine performance, the fuel controller design becomes more crucial. In this case, the control requirements include the fuel flow control for both steady-state and transient modes. The fuel flow control is * Corresponding author. E-mail address: montazeri@iust.ac.ir (M. Montazeri-Gh). a natural control parameter to provide good control of turbine in- let temperature (TIT), good reaction to burner blowout and indirect control of compressor surge margin. Several methods have been used for design of the GTE fuel con- trol including linear and nonlinear methods [10,4,9,24,2]. Using a linear method, the system is linearized at several operating points and a set of linear controllers is scheduled. These piecewise-linear designed controllers operate nicely at the vicinity of the points around which the system is linearized. However, jet engine char- acteristics are highly non-linear and thus an intelligent method based on the physical understanding of the engine performance requirements and constraints may lead to a more competent con- troller. Fuzzy logic is an attractive technique for the control of non- linear and complex systems where the experience of human op- erators is available to provide qualitative “rules of thumb” [19,11]. Since Zadeh first introduced the concept of fuzzy sets [22], there has been a rapid growth in the number and variety of applications of fuzzy logic, especially in modeling and control. Previous studies have demonstrated that fuzzy logic control could be applied to the design of controller for GTE [10,4,9,24,2,3] and [13]. The fuzzy logic control (FLC) has many advantages such as simplicity in implementation and no need to the mathematical model for design. However, due to the complex nature of the gas turbine aero-engine, FLC design based on the engineering intuition 1270-9638/$ – see front matter © 2010 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.ast.2010.10.004