Research And Matching Analysis On Coupling Calculation Method Of Gas Turbine And Air System

With the development of gas turbine technology, the rise of the temperature of the turbine and the high temperature resistance of the turbine blade are the result of the increase of the air system.Therefore, it is of great value to study the coupling calculation method of gas turbine and air system.In this paper, the overall performance of the gas turbine is simulated which considered the effect of air system on the basis of the previous research results and the theory of engineering pneumatic。At the same time, it studies the modeling method of compressible flow in air system, which lays the foundation for the integrated modeling and calculation of air system and gas turbine.Based on the thermodynamic theory, the thermal calculation method of gas turbine is studied,which determined the method of variable specific heat to calculate the working medium’s quality parameter and isothermal enthalpy difference method to calculate the combustion chamber oil gas ratio. On this basis, the thermal performance calculation model of the gas turbine components including the inlet, the compressor, the combustion chamber, the turbine and the nozzle is established,and the calculation of the thermal parameters of the gas turbine from the inlet to the outlet of the cross section of the gas turbine is completed. Based on common working condition of gas turbine, the matching calculation method of Newton-Raphson iterative solution is determined, for the processing of the characteristic curve of the rotor parts, which use the non aligned data two element interpolation method to extract performance of compressor turbine. At the same time, for the calculation of high speed gas flow in the air engine air system, fluid network method is used to model the node branch network. And using generalized one-dimensional flow theory, via comparison transformation and the Runge Kutta numerical integral method solving differential equations,obtained the method for solving the flow parameters of simple branching structures(Gradient section heat pipe flow); Using empirical loss coefficient method to solve the relationship between the inlet and outlet flow parameters of complex structures(Abrupt area change,Bends,Screens and Gratings,Tee junction),finally forming a set of compressible fluid network loss solution library, It provides the basis for the calculation of air system and similar gas pipeline network.According to thermodynamic calculation model we have researched, which considered the effect of air system on the overall performance of the gas turbine which bleed air from the high and low pressure compressor to cool the turbine blade,the coupling calculation tool for gas turbine and air system is developed. Aiming at a certain type of aeroderivative ground gas turbine, the variation law of gas turbine performance under different working conditions, different throttle angle and different power turbine guide are calculated and analyzed.And especially for the influence ot the air systems,on the condition of given nozzle area and power turbine output speed,following conclusion are drawn:keep throttle angle constant,with the increase of bleeding air, turbine front temperature is increasing,output power is increasing,the specific fuel consumption first rise and then drop; keep throttle angle adjustable,let bleeding air increased by the rise of turbine front temperature, the specific fuel consumption first drop and then rise,there exsist the minmum specific fuel consumption.