Gas turbines are applied at increasingly smaller scales for both aircraft propulsion and power generation. Recuperated turboshaft micro turbines below 30 kW are being developed at efficiencies competitive with other heat engines. The rapidly increasing number of unmanned aircraft applications requires the development of small efficient aircraft propulsion gas turbines.
Thermal effects such as steady-state heat losses and transient heat soakage on large engine performance are relatively small and therefore often neglected in performance simulations. At small scales however, these become very significant due to the much higher heat transfer area-to-volume ratios in the gas path components. Recuperators often have high heat capacity and therefore affect transient performance significantly, also with large engine scales. As a result, for accurate steady-state and transient performance prediction of micro and recuperated gas turbines, thermal effects need to be included with sufficient fidelity.
In the paper, a thermal network model functionality is presented that can be integrated in a gas turbine system simulation environment such as the Gas turbine Simulation Program GSP . In addition, a 1-dimensional thermal effects model for recuperators is described. With these two elements, thermal effects in small recuperated gas turbines can be accurately predicted. Application examples are added demonstrating and validating the methods with models of a recuperated micro turbine. Simulation results are given predicting effects of heat transfer and heat loss on steady-state and transient performance.