Schlussbericht
(Englisch)
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The purpose of the project has been the further development and utilisation of a novel experimental test facility (Spray Combustion Chamber – SCC) with optical accessibility, which represents the combustion chamber of a 2-stroke marine diesel engine and allows the investigation of in-cylinder processes at realistic conditions. This involves the enhancement of the experimental setup (also in view of a potential use in the context of product development projects) as well as the further development of existing and the application of new technologies with the ultimate target of generating a comprehensive set of reference data, which can be used for the validation and improvement of CFD tools.
One main topic has been the ability to operate the SCC on different fuels, including customary marine fuel types. In this respect, the operational flexibility and efficiency have been considerably enhanced by implementing an additional fuel injection system for heavy fuel oil. A next step is already in progress, which shall enable the investigation of even very small quantities of either model or alternative fuels or even of samples of fuels of different quality actually used on board vessels.
Another major achievement has been the redesign of the covers for improved optical accessibility, which clearly reduces the efforts during measurement campaigns for observing the spray along its full penetration. On the one hand, a significantly smaller number of measurement locations (window positions) is required. On the other hand, also the change of window position can be realised more efficiently as the need for rotating the covers is almost limited to a minimum.
Following the optimisation of the experimental setup for shadow-imaging investigations, the range of measurement techniques has been extended by applying Mie-scattering, OH*-chemiluminescence and Phase Doppler Anemometry. The applicability of all these techniques has been demonstrated and first results have been obtained with respect to droplet sizes and velocities as well as ignition and combustion behaviour.
These technologies will also be applied in the future for complementing the reference data base for spray propagation, which has been established in the course of the present project and consists in relevant characteristics such as penetration and spray angles for a whole range of conditions. The variations considered include the most important parameters for (single) light fuel oil sprays such as chamber pressure and temperature, injector orifice size, spray orientation with respect to the swirl, swirl intensity or injection pressure. Further investigations into fuel quality effects will be performed in order to extend the range of applicability of this comprehensive reference data set, which is already now extensively used for the validation of CFD modelling approaches.
Regarding more product development related investigations, the potential of the SCC has been confirmed by realising a special configuration allowing the observation of sprays from actual production injectors. Moreover, its versatility has been demonstrating by using it for studying lubricant oil injection at conditions relevant for lubrication systems on large twostroke engines.
The investigations confirm the potential of the experimental test facility for studying spray and combustion processes at conditions relevant to large marine diesel engine combustion and extend the information on spray characteristics at such conditions.
All in all, the Spray Combustion Chamber has clearly demonstrated its value: It has proven its robustness and can be operated at high levels of reliability. It allows generating data, which are characterised by outstanding reproducibility and very high quality. The data processing, which has been specifically devised, enables the fast and efficient analysis of the raw data obtained in order to derive relevant scientific conclusions. Its unique features and high versatility make it a very powerful and invaluable tool both for fundamental research into spray and combustion processes and for enhancing product development by assessing the performance of new components and systems that can be applied to it. Its availability to the Swiss research community must be seen as a major asset in terms of the competitive position of the contributing partners.
Auftragnehmer/Contractant/Contraente/Contractor:
Autorschaft/Auteurs/Autori/Authors:
Weisser,German
Schmid,Andreas
Herrmann,Kai
von Rotz,Beat
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