Alternative method to simulate a sub-idle engine operation in order to synthesize its control system

The steady-state and transient engine performances of gas turbine control system development are usually evaluated by applying full thermodynamic engine models. Most models only address the operating range between the idle and maximum power points, but more recently, they also address a sub-idle operating range. The lack of information about the component maps at the sub-idle modes creates major challenges for the starting system and control system designers. A common method to cope with the problem extrapolates the performances of the engine components to the sub-idle operation range. Precise extrapolation is a challenge to be studied by many scientists. As a rule, many scientists are only concerned about particular aspects of the problem such as the lighting combustion chamber or the turbine operation under the turned-off conditions of the combustion chamber. However, there are no known reports about a model that considers all of these mentioned aspects and simulates the engine starting. To synthesize a thermodynamic model of starting, most known methods require the performance of the components in the sub-idle range. The proposed paper addresses a new method that simulates the engine starting. The method substitutes the non-linear thermodynamic model with a linear dynamic model, which is supplemented with a simplified static model. The latter model is the set of direct relations between parameters that are used in the control algorithms instead of commonly used component performances. Specifically, the static model consists of simplified relations between the gas path parameters and the corrected rotational speed. The paper also describes an algorithm for model synthesis and its practical application to real data.