A Code for Thermal Analysis of STIG Turbines

A computer model to evaluate the off-design performance of steam injection gas turbines (STIG) has been developed; the code utilizes turbine and compressor curves, and requires only one operation point as further input parameter. The global thermal analysis has been performed by means of the iterative solution of a non-linear equations system.The model is based on the following hypothesis: air convection/film cooling process and turbine choking condition.The prediction of air cooling flow has been correlated to the air temperature, function of the compressor efficiency and the bleed point pressure and to the gas temperature, directly related to the work output. The thermal exchange between blades and hot gas has been computed by means of a model proposed in literature.The code is a handy tool to predict the off-design performance of STIG plants, also it can simulate the analysis of existing plants in order to evaluate the feasibility of some implementations.An interesting analysis of the performance of a real STIG plant has been carried out and the comparison between the calculated and the experimental curves validates the computational procedure.Copyright © 1995 by ASME