Development of a Gas Turbine Performance Software Including Sub-Idle Region and Starting Process

Abstract

This study aims to develop a computer software to mathematically model a gas turbine engine's design point, steady state off-design and starting phases. Having a computer simulation software is crucial for a engine development project in terms of budget and schedule. In this scope, a component matching based performance code has been developed. Above-idle code results are validated by comparing with commercially available GasTurb13 results. Additionally, by using engine information found open literature, another performance model is created for T700-GE-700 turboshaft engine and results are validated by comparing the code results and open literature data.

For engine starting modeling, sub-idle component performance characteristics are required. Generally, physics based sub-idle performance models cannot be created since computational fluid dynamics solvers and component test rigs cannot produce reliable results for this particular region. Optimisation studies for starting process like fuel scheduling or controlling the maximum temperatures in internal stations are widely performed by the help of engine tests due to the absence of the performance model. In this thesis study, sub-idle performance characteristics are estimated by extrapolating the well-known above-idle characteristics towards zero-speed point. Additionally, by taking the starter torque-speed characteristic from open literature, a sample starting model was created for T700-GE-700 turboshaft engine. By comparing the obtained results with open literature found engine starting data, it is observed that the map extrapolation method produces very realistic outputs even it has lots of uncertainties