| Summary: | The principal aim of this research was to provide a detailed understanding of the
performance of gas turbine engines inside indoor sea-level test beds. In particular the
evaluation of both thrust correction factors and the estimation of the mass flow
entering the test cell were at the core of the research.
The project has been fully sponsored by Rolls-Royce pIc. Initially, their principal
objective was to assess the relevance and accuracy of CFD when applied to thrust
measurement inside indoor test beds with an intended outcome of minimising the use
of expensive experimental measurements.
The different system interfaces and accounting systems for in-flight conditions,
available in the open literature have been developed and adapted for indoor
environments. This has led to the definition of three different thrust correction
equations using alternative definitions of thrust correction factor. Aero-dynamic
principles have been applied for the derivation of one-dimensional relationships for
the calculation of each thrust correction factor using generic engine-cell performance
and dimensions.
A one-dimensional analytical model has been developed to represent the enginedetuner
ejector pump. This is able to characterise the engine-cell system performance
and is used as the main tool for providing a matching procedure capable of predicting
the cell entrainment ratio.
By processing experimental data relevant to different engine-cell configurations
through the ejector pump analytical model, a method for achieving the entrainment
ratio control inside the cell has been identified.
The CFD work has been concentrated into three main activities:
• A quantitative extrapolation of the thrust correction factors including, the
pre-entry force, the external and the total bellmouth force, the throat stream
force, the intake momentum drag and the base drag.
• The representation of the engine-detuner ejector performance for a
variety of engine-cell configurations.
• The modelling of the generic test cell components including the inlet
stack, the cascade elbow, the exhaust stack & the blast basket.
The outcomes of this research have been very successful in enhancing the validity of
the thrust correction equations developed .. In particular, the use of a one-dimensional
approach in their estimation has been shown to be fully justified. The work has also
emphasised the value of CFD in supporting the derivation of the matching procedure
for predicting and controlling cell entrainment ratio. Indeed, one of the strongest
outcomes of this work has been the conclusion that both the engine-cell characteristic
lines computed with the one-dimensional model and those computed with CFD for
different cell configurations are almost identical.
In addition, the use of CFD as a tool for the quantitative evaluation of the thrust
correction factors has been established. Finally, the CFD results have facilitated an
enhanced understanding of the complex flow structure inside indoor test cells
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