Off-Design Behavior And Operation Optimization Methods Of Marine Intercooled Gas Turbine

Gas turbine has been known as "the flower of industry".Continuous improvement of gas turbines performance is an eternal topic.Aiming at the future requirement for domestic high-powered gas turbines applied to ships,developing advanced core engines as well as developing intercooled gas turbines based on existing simple cycle gas turbines is an important means and effective approach.An intercooled gas turbine has tighter coupling and more nonlinearity than a simple cycle gas turbine,leading to the complexity of its off-design modeling,performance analysis and operation optimization.This thesis takes a marine three-shaft intercooled gas turbine for example,by computer simulation,to carry out research on methods of off-design behavior analysis and operation optimization.characteristic of gas turbine components is the basis of off-design condition calculations of intercooled gas turbine.Kriging method has advantages of linear optimal and unbiased interpolative in spatial estimation,while its application is restricted by the difficulty of model selection and kriging equations solution.In order to avoid subjectivity in model selection and the difficulty in kriging equations solution,this thesis presents a method of characteristic maps re-engineered based on the selection and assessment of kriging models on GIS software platform.Simulation results show that re-engineered characteristic maps have high accuracy,favourable smoothness and spatial continuity,which can provide data support for the off-design calculation of intercooled gas turbine.The operation optimization of intercooler is the basis of the operation optimization of intercooled gas turbine,but was ignored in previous studies.In this thesis,the coupling of the system is weakened by defining a parameter named equivalent intercooler effectiveness,and a mathematical model is built for calculating off-design condition of indirect fluid coupling type intercooler.Calculation results indicate that both temperature drop and pressure drop on the air side of intercooler have a linear negative correlation with equivalent intercooler effectiveness,while the operating energy consumption has a nolinear positive correlation with equivalent intercooler effectiveness.Furthermor,a multi-objective optimization model of the intercooler operating is established and a stratified sequencing method based on variable step search is designed to solve it.The simulation results show that this method can perform fast convergence to global optimal unique solutionAn off-design condition model is built for calculating all balance condition of a marine intercooled gas turbine,with three parameters of equivalent effectiveness,low-pressure rotor speed and power turbine speed as degrees of freedom.Accordingly,the performance space is extended from traditional two dimensions of simple cycle gas turbine to three dimensions of intercooled gas turbine.Graphical method is developed for solving the problem of multistage decision and nonlinear programming,which can be used to optimize the intercooling gas turbine operation on steady state in three dimensional space.Simulation results show that graphical method can design the optimum operating curve for marine three-shaft intercooled gas turbine intuitively,and subsection control strategy is obtained,accordingly.Limitation is verified of marine three-shaft intercooled gas turbine based on the concept of the simplest modification.And the equilibrium points on the optimum operating curve will provide reasonable original state and target state for subsequent dynamic simulation.Intercooler increases thermal inertia and volume inertia of the system,so it is very necessary to study the effect of them on the transient behavior of intercooled gas turbine.In this thesis,subsection dynamic modeling and transient simulation of fluid coupling type intercooler is carried out.On this basis,the nonlinear dynamic model of intercooled gas turbine is established,and the effect of thermal inertia and volume inertia on the transient behavior of the whole system is discussed.Simulation results show that gas turbine response presents significant inertial delay when sea water flow change independently,the inertia of on-engine intercooler plays a dominant role on gas turbine response when EG and sea water change at the same time,and great difference exists in response under different multivariable combination of inputsAt present,the researches of dynamic performance of intercooled gas turbine from one operating condition to another are mostly by means of contrasting open loop response among different inputs.In this thesis,the integrated control of intercooler and gas turbine is initially explored.Firstly,a method of adaptable genetic algorithm is designed for identifying the state space model of the intercooled gas turbine.With replacing the sign function by the saturation function,the control law of intercooling cycle is acpuired by multivariable sliding mode control method with input integrals.Simulation results show that the obtained closed-loop control can tracking the target instructions fastly and without chattering phenomenon.