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TIMECOP-AE
Toward Innovative Methods for Combustion Prediction in Aero-engines

Tags: Air

Background

The pressing demand to reduce emissions and noise levels in future aeroengines is of the greatest importance. These points are evidenced through the very ambitious pollutant and noise reduction targets set for 2020.

Several combustion technology-related programmes are underway to support these objectives, e.g. LOCOPOTEP, INTELLECT D.M. However, these programmes are not dedicated to improve methodology. Within previous European programmes (MOLECULES, CFD4C, LESSCO2, etc.) advanced computation fluid dynamics (CFD) models, lower order models, and methodology rules have been developed in order to support the design of a low emission levels combustion chamber that will satisfy these 2020 targets. Within these projects, the main focus was on improving emissions at full power conditions. Little work was done on the modelling of unsteady phenomena including combustion and liquid spray modelling.

In TIMECOP-AE, the next major step forward is made: modelling aeroengine combustors which operate on liquid fuel and developing the capability to perform transient analysis. For this step to take place, the development of improved turbulence, turbulence-chemistry interaction, spray dynamics and the building blocks to model unsteady phenomena are required. This next step will further close the gap between the numerical model capabilities and the actual aero-engine combustors operating on kerosene.

Objectives

The main objective of the project is to enable European industry to design and develop innovative, optimised, low emissions combustion systems within reduced time and cost scales. This will be made possible by the development of state-of-the-art methods in the field of combustion modelling. These prediction methods will give the European industrial partners the advantage to improve in three pertinent fields:

Operability:

  • ability to model a wide range of operating conditions,
  • ability to model and cope with transient conditions,
  • ability to model and thus avoid combustion instability,
  • ability to model and secure capability for altitude re-lights.

Emissions:

  • capability to lower combustion system emission levels during the design phase,
  • ability to handle different fuel chemistry and calculate biofuelled engine.

Competitiveness:

  • reducing development costs by attaining higher combustion module maturity before development tests,
  • allowing more efficient design optimisation.

Within the MOLECULES project, significant advances were made in developing LES codes for turbulence modelling for combustors operating on gaseous fuels. Within this TIMECOP-AE project, it is proposed to extend this capability to liquid-fuelled combustors.

TIMECOP-AE overview
TIMECOP-AE overview
TIMECOP-AE

Description of work

Within TIMECOP-AE, the LES tools will gain the capability for modelling the combustion process within conventional and low-emission combustors over a wide range of operating conditions on liquid fuels. The operating conditions include mentioned transient phenomena. To be able to model these phenomena, improvements are required in the models of turbulence, chemistry, turbulence-chemistry interactions and liquid spray models. The methods and models will be evaluated against high-quality validation data which will be obtained by several validation experiments. Some are designed to validate specific models: one is a generic combustor, representative of an aero-engine combustor, and permits assessing the full range of models.

Results

CFD tools based on the LES approach will be developed to allow predictions of whether a combustion chamber will blow out or not at landing conditions. This is critical to the adoption of advanced combustor concepts. Another important operability aspect is whether or not the combustor will re-light at altitude. It is extremely difficult to comply with the requirements for these aspects for lean burn combustors, since lean mixtures are more difficult to ignite and are close to the lean extinction limit. Current CFD methods are obviously lacking in predicting these transient phenomena. These operability issues are challenges that have to be addressed before low-emission combustors can be realistically introduced into the next generation of aero-engines.

Currently it is prohibitively expensive and time consuming to perform rig testing to determine the operability of advanced combustor designs. TIMECOP-AE will develop the tools to allow virtual prototyping of new concepts, which will significantly reduce the testing required, thereby reducing cost and time taken to introduce innovative combustion technology into production engines.

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