Modelling and simulation of transient thermal loading in a gas turbine

摘要

The nozzle guide vane of the gas turbine is considered to be one of the most critical engine components from a thermal stress point of view. Hot gases from the combustor exhaust heat the outer surfaces of the vane, and because the turbine vane is cooled internally by air diverted from the compressor, a temperature gradient results between the inner and outer surfaces of the vane. These high gradients often make the nozzle guide vane the most likely engine component to fail due to low cycle fatigue. During engine transients each engine acceleration and deceleration induces a cycle of thermal stress, which can eventually cause component failure. Therefore it is very important to predict the thermal loading of turbine components and assess how that can affect component life. For that purpose a heat transfer model for a cooled turbine component has been developed taking advantage of simplifications in heat flow analysis. Numerical simulations have been carried out using the generic gas turbine simulation tool GasTurboLib. This Simulink library enables 0-D modelling, which is the simplest level of modelling, but most widely used in industry. The developed model of a cooled turbine has been implemented into turbine block of GasTurboLib library, enabling simulation and analysis of heat transfer effects within turbine components in more details. The transient behaviour of a gas turbine during full load acceptance has been simulated to validate the proposed model against engine test data, and good agreement with test results has been observed. Analysis of thermal loading for a turbine component during engine rapid transients has been carried out and numerical results are presented in this paper.