Objectives :The main objective of the project is to optimise combustion in direct injection Diesel and gasoline engines, through the improved understanding of fuel - air mixing with special emphasis on the evaporation process and impingement against hot surfaces like the piston or cylinder walls, which have shown to be major problems of current direct injection engines. More specific objectives are:
- To develop and use modern experimental techniques for spray characterisation and to optimise research methodologies. - To generate a wide data base of experimental results on spray behaviour under close to real engine situations- To develop and validate new sub models of spray evaporation and impingement, to be integrated into existing solvers for predicting spray behaviour.
- To obtain clear guidelines for optimisation of the combustion process in modern direct injection Diesel and gasoline engine.
Description of the work: The project objectives will be achieved by a combination of measurement and calculation methods which will be partly developed for this purpose. The experiments, to be performed in a high number of advanced, purpose-made experimental facilities, with state-of-the-art measurement equipment. They will include fundamental research to go deeper into the physical mechanisms of evaporation and impingement, as a necessary task for proper modelling, as well as measurements close to engine conditions. Advanced high pressure Diesel and gasoline direct injection systems will be used as the basis for the experiments, which will be performed in different injection test rigs and in engines, with geometry and spray air-flow characteristics as the main variables. New evaporation and impingement sub models will be developed on the basis of fundamental experimental research, and they will be validated and optimised on the basis of the more complex experiments in close to engine situations. Current codes will be used in parallel to provide some relevant information to guide the experiments and to improve understanding of the most complex phenomena of spray combustion, but also to evidence the deficiencies of the currently available codes. Expected results and exploitation plans: The gained knowledge on the physical phenomena inherent to spray development will hopefully provide clear guidelines to optimise combustion in internal combustion engines with current and alternative fuels and injection systems, which will be directly used in the design of new generation engines. It is also expected that new ideas on viable new concepts on spray formation systems will arise from the results, which will be further evaluated by the Industrial partners at the end of the project. The validated models will be implemented into an existing commercial code which is currently used all around Europe in a large number of industrial sectors which make use of sprays. New measurement techniques will be developed throughout the project, which will have further applicability to other kind of research problems. The basic scientific and technical knowledge gained will be published in conferences and scientific journals when possible.
Several purpose-made experimental facilities have been set up successfully for the study of evaporating and/or impinging sprays
- A new processing method for Particle Image Velocimetry technique has been developed and evaluated to characterise liquid fuel droplets in the proximity or not of solid surfaces
- A novel back-scatter miniaturised Phase Doppler Anemometry probe for drop size and velocity measurements with restricted optical access has been designed and constructed. However, the expected results have not been obtained, and it has not been possible to use it as a systematic research tool
- Optimised methodologies for high-speed visualisation techniques, including Laser Induced Fluorescence have been developed to analyse the vapour phase of Diesel and gasoline sprays in rigs and optically accessible engines
- New evaporation and impingement submodels have been developed and implemented into existing flow solvers
- A data base of experimental results about the physical processes of sprays in engine conditions has been created.
Funding SchemeCSC - Cost-sharing contracts
76801 St Etienne Du Rouvray
SW7 2BX London
78210 Saint Cyr L'ecole
76801 St Etienne Du Rouvray