TIMECOP-AE - Toward Innovative Methods for Combustion Prediction in Aero-Engines
Overview
Background & policy context:
Predictive tools are required to be able to reduce NOx emissions, to decrease the development time and costs of new combustion systems and to improve the operability of lean-burn combustion systems. Most promising approaches to satisfy future emission levels regulations are based on lean combustion technology. However, lean combustion compromises combustor operability, including ignition, altitude re-light, pull-away, weak extinction performance and thermo-acoustic instability behaviour. Therefore it is of prime importance to evaluate the behaviour of the flame during these transient phases in the design stage and modelling tools are required. Without these tools the development of advanced combustion systems relies on many costly and time consuming rig tests. The high-fidelity simulations proposed in TIMECOP-AE are therefore a way to increase competitiveness.
Objectives:
The aim of the FP6 TIMECOP-AE project was to improve the necessary combustion prediction methods that enable the development of practical advanced combustion systems for future engines, with reduced emission levels and fuel consumption.
The main objective of the project was to enable European industry to design and develop innovative, optimised, low emissions combustion systems within reduced time and cost scales. This would be made possible by the development of state-of-the-art methods in the field of combustion modelling. These prediction methods would 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.
Methodology:
To reach the main objective of advancing LES methods into two-phase flows for gas turbine applications, TIMECOP was divided into 4 Work Packages and the technical activity distributed as follows:
WP1 - Fundamentals
Within this work package, numerical models for two-phase flow, chemistry and ignition were developed, improved, evaluated and tested. Both Eulerian and Lagrangian two-phase models were considered, and the performances of the two approaches compared. Chemistry models were developed to application to LES. Approaches are based on the Flamelet Generated Manifold method, the Conditional Closure Model, the Field PDF method, and the Computational Singular Perturbation method. Furthermore, a specific spark ignition model has been developed. The models were implemented in numerical solvers and exploited by industrial partners.
WP2 - Validation experiments
WP2 focused on teh development and application of advanced diagnostic techniques on geometries and flow problems ranging from very well defined, easy-to-characterise, academic test cases to industrial test cases. The former tests were used to support model development, the latter to validate models in presence of complex geometries and ambiguity in boundary conditions.
WP3 - Numerical validation and implementation of fundamentals
The aim of this work package was to integrate the fundamental models into the advanced CFD methods, in order to obtain the two-phase reactive CFD capability and resolve the intrinsic unsteady behaviour of turbulent flows. To ensure the proper implementation of these new models, validations were first performed on academic experiments. Once validated, the advanced CFD methods were ready to be tested on complex 3D geometry experiments.
WP4 - Exploitation
LES of reactive two-phase flow is the next evolution in CFD methodologies applied to the conception of aeronautical engines. It should complement and eventually replace existing RANS conception techniques. The justification of this evolution resides in the fact that engine performances and transient phases are not predictable with the only use of RANS.
Share this page