Generation of Physically Based Analysis Factors to Improve Synthesis Models of Jet Engines

Abstract

The ANalysis by SYNthesis (ANSYN) technique is a standard performance analysis method widely used in industry. It is currently used to evaluate engine performance from tests and to derive correcting factors (i.e. ANSYN factors) that modify certain parameters of the components’ characteristics in order to allow the reproduction of real engine behaviour by means of a synthesis calculation. Once they have been determined, these ANSYN factors can be implemented into the common synthesis tools to accurately predict the behaviour of the engine in non-tested conditions. The definition of how the engine synthesis will be modified to reproduce the measured cycle is called the “matching scheme”. It is the choice of the parameters that will not be modified, the ones that will be scaled and the ones that will be used as a reference. A good choice of the ANSYN factors and of the magnitudes used to tabulate them will make possible their physical interpretation and analysis, which can lead to the identification of inaccurate assumptions and phenomena that had not been accurately taken into account in the previous performance models. This understanding of their origin is a prerequisite for any improvement of the models and could lead to an enhanced process for the development of non-dimensional jet engine characteristics. In this study, a matching scheme for the RR-BR710 engine has been set up, implemented and applied. This method is an alternative to some of the currently used in the Rolls-Royce Deutschland ANSYN tools. The main goal of the present work has been the definition of a matching scheme that leads to the obtention of physically meaningful ANSYN factors. This allows their subsequent analysis and interpretation and can provide useful information on engine component operation and on the phenomena responsible for the observed deviations from predicted engine behaviour.