Model based performance analysis from an engine manufacturer point of view

Gas turbine engine manufacturers usually apply full thermodynamic models to the prediction of engine performance. The performance calculation tools are modularly structured and synthesize the performance of the engine based on the characteristics of its individual components. Using these tools, a full thermodynamic model of nearly any engine configuration can be set up, allowing the calculation of engine performance with sufficient accuracy. During engine development programs the evaluation of the engine performance from test data is generally accomplished by a model-based analysis procedure. Compared with in-service engines the performance instrumentation of development engines is very extensive. With such instrumentation it is possible to break down the engine performance to component level. The basis of the analysis procedure is a full thermodynamic model representing the expected component characteristics of the engine. The model is matched to the engine test data on a component level by applying so-called modifiers. On the one hand this allows calculating all data which is not directly measured, e.g. turbine temperatures, efficiencies and specific fuel consumption. On the other hand a comparison between the test data and the expected component characteristics is performed. The deviations are characterized by the derived modifiers. The way the comparison is done allows analyzing the components almost separately from each other and thus matching effects are nearly eliminated. This paper describes typical applications of such a model-based analysis procedure during engine development programs, such as the validation of performance models as well as the support of engine tests to ensure a safe and efficient engine operation