Objectives and content
A major challenge is to respond to current and prospective public concerns regarding the nuisance and disturbance caused by aircraft emissions upon the atmosphere, in particular at high altitude. Indeed, one of the major problems that civil aeronautics will have to face over the next twenty to thirty years is to accommodate the predicted growth in demand of air transport without adverse effects on the environment. To overcome this problem will require both the development of advanced, environmentally benign technologies and the conduct of scientific research to increase the understanding of basic phenomena. A particular concern relates to the possibility that emissions of oxides of nitrogen (NOX) and other minor species from aircraft flying in the upper troposphere and lower stratosphere (8-25 km)! whether from current subsonic or, in the future, from possible supersonic operations, may make a non-negligible contribution to global warming and ozone generation or depletion. In the preceding phases of this Framework IV programme (Pilot Phase /l/ and Interim Phase 12/), three major methods of Nitrogen oxide reduction were identified. These methods differ not only in their NOX reduction potential, but also in their complexity and technical feasibility. The first concept with the lowest NOX reduction potential incorporates the lean combustion method without premixing in a staged - Double Annular Combustor - design . The second method also uses lean combustion but improvements in NOX reduction can be obtained by introducing a premix duct so that a Lean, Premixed and Prevaporized combustion system is developed. The third concept, applying the Rich burn, quick Quench Lean burn combustion has a smaller rechnical risk than LPP still providing a considerable amount in NOX reduction.
Efforts in the Interim Phase of the programme proved the Double Annular technology to be prepared for introduction by l995 with an expected overall NOX reduction level of about 30% to 40%. For the first time, LPP systems could be tested during the Interim Phase at pressure levels up to 20 bar (small engines) and 17 bar for large engines respectively, without experiencing any damage. RQL combustors were tested up to 6 bar and 750 K entry temperature reaching a NOX reduction of 60%, relative to current ICAO regulations. Consequent upon the recommendations and results of the Pilot and the Interim Phase of this programme, the main objectives of this proposal are:
- demonstration of the most promising NOx reduction techniques in test combustors at simulated engine operating conditions for large and small engines,
- the measurement of the potential of NOx reduction reached by application of the ultra low NOx combustion systems selected,
- and the evaluation of these combustion systems concerning essential performance features such as safety, integrity and engine control. Development and demonstration of pre-competitive technology is proposed for: - the lean premixed and prevaporized combustion on a practicable experimental basis, e.g. integration into practical combustion hardware and evaluation of the emissions reduction potential over the full range of realistic engine operating conditions
- the application of a rich, quench, lean burning pilot stage combustor in connection with a staged system of which the combustor architecture is most likely to lead to a practical combustor
- evaluation of possible improvements in designs and component technology in a study focused on fundamentals
- investigation of combustion control systems to be used with future staged combustors
- validation of CFD combustion models.
The proposed investigations will not only be of benefit to the development of low emission combustion chambers for all gas turbines burning liquid fuel (subsonic aero engines, SSTs and land based industrial gas turbines) but will also contribute to the improvement of several tools for the design of all gas turbine combustion chambers and their components. The consortium consists of ten European aero engine manufacturers supported by sixteen research establishments and universities; altogether, there are twenty six collaborating partners from eight European states.
Funding SchemeCSC - Cost-sharing contracts
86961 Chasseneuil Du Poitou
MK43 0AL Cranfield - Bedfordshire
10127 Torino (Turin)
80038 Pomigliano D'arco
221 00 Lund
DE24 8BJ Derby
GU14 0LS Farnborough
461 81 Trollhättan