Abstract

In this paper a comparison of the performance parameters and flow characteristics of a mature commercial high bypass engine’s 9-stages high pressure compressor (HPC) with steady-state mixing-plane (RANS) and unsteady RANS (URANS) CFD is carried out. The investigation is based on a numerical model of the CFM56-5C engine’s HPC which is installed on the Airbus A340-300 aircraft. The compressor under investigation features the so called 3D blading which is the first of two performance improvement packages available. An experimental engine of this type equipped with extensive additional instrumentation is in use by Lufthansa Technik to deliver detailed experimental data of the gas path. Experimental results have been discussed in previous works of the authors.

In order to provide long-term forecasts of an engine’s state the aforementioned CFD model has been included into a multilevel engine model.

To be able to evaluate the significance and applicability of the CFD results into such model, it is of great interest to which extent and level of detail it can deliver accurate performance predictions.

From the comparison of both steady-state and unsteady simulation results it is found that overall compressor performance only differs negligibly while stage performance can differ significantly. It is depicted that among the stator vanes of the front stages local supersonic flow and flow separation can occur. These are not captured by the steady-state simulation to the same degree a time resolved simulation does. In rear stages differences fade and unsteady methods tend to predict better stage performance which may be due to favourable effects of rotor-stator interaction.

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