Characteristic And Control Law Investigations On Variable Geometry Triaxial Gas Turbine

Triaxial gas turbine with variable power turbine inlet guide vane has the advantages of high power to weight ratio,strong ability of load adaptation and is easy to start.The gas turbine can be adapted to various working conditions by adjusting the power turbine inlet guide vane angle to change power turbine and upstream gas generator performances,which causes excellent performance in acceleration and deceleration characteristic and part-load working conditions.However,the gas turbine with complex structure and variable power turbine inlet guide vane brings challenges in engine models and control law designs as below:Firstly,traditional simulation models are difficult to acquire excellent real-time performance and computational precision simultaneously as the gas turbine with the complex structure causes prominent multivariable strong-nonlinearity problem.Secondly,the angle of power turbine inlet guide vane affects power turbine itself and twin-spool gas generator performances.It is profound to optimize the control law and keep the gas turbine operating under the optimal performance for unpredictable working conditions,atmospheric environments and load conditions.Finally,during the process of regulation in power turbine guide vane,twin-spool gas generator outlet pressure characteristics under coupled effects of multi-factors still need to be further explored.However,there are few researches on real-time simulation and control law for this type of gas turbine at home and abroad.This paper,firstly,built component-level simulation model for the triaxial gas turbine with variable power turbine inlet guide vane.A Hybrid Method(HMRC)comprised of Radial Basis Function(RBF)neural net algorithm and Component Modeling Method(CMM)was developed to build real-time simulation model based on the established component-level model.The established real-time model was verified that it satisfies the hardware-in-the-loop simulation experiment requirement for control system.And then,the gas turbine performance was studied detailedly based on the simulation model and experiment data.According to the gas turbine performance,on the one hand,fuel mass flow rate and guide vane angle coupling control strategies were developed in the view of optimizing control law to enhance thermal efficiency and maximum output power at the condition that gas turbine key parameters do not exceed maximum limits.On the one hand,the relationship between twin-spool gas generator outlet pressure characteristics and component characteristics was studied in the view of guiding component design,and the research results were validated by gas turbine rig test data.The above researches provide significant reference for triaxial gas turbine with variable power turbine inlet guide vane modeling,building control strategies and guiding component performance designs.The main research contents are showed as follow:(1)Each component in the gas turbine was modeled respectively based on the existing component characteristic maps and gas thermodynamic property calculation method.Newton-Raphson algorithm was utilized to solve the non-linear equation set and acquire the cormmon operating points.The component-level simulation model,including design point model,steady model and transient model,was established for the gas turbine in MATLAB/SIMULINK.(2)Considering traditional simulation model cannot satisfy accuracy and real-time performance requirements from hardware-in-the-loop simulation experiment,this paper took advantage of radial basis function neural network and component-level modeling method to develop a hybrid modeling method(HMRC).The accuracy and real-time performance of the hybrid model were validated by the traditional component-level model and the hardware-in-the-loop simulation experiment.(3)The established simulation model was utilized to analyze the gas turbine performance changing with atmospheric environment,the influence of power turbine guide vane angle on gas turbine performance and restriction factors of maximum output power under various atmospheric environments,et al.,which were applied to investigate the control strategy in the following text.(4)Two control strategies,High Efficiency Mode(HEM)and High Power Mode(HPM),were developed and optimize fuel and guide vane control laws to respectively improve off-design efficiency and maximum output power for unpredictable environments.The control strategies were validated via the established controller model simulating in SIMULINK.HEM and HPM respectively enhanced thermal efficiency and maximum output power by 2%and 5%under certain working conditions.(5)A linear model was derived to research the component match problem in high-and low-pressure rotors as the twin-spool gas generator outlet pressure changes.The mathematical relationship between component characteristics and twin-spool gas generator outlet pressure characteristics was built,which can be employed to guide component performance design.The simulation results indicate that the linear model can guide component design and avoid high-pressure shaft rotational speed increasing with the increase of gas generator outlet pressure effectively.