Variable Orifice Geometry Verified on the Two-Phase Nozzle (VRD)

Innovative solutions for reducing particulate emissions will be necessary in order to comply with the even more stringent exhaust-gas standards of the future. The potential of a diesel nozzle with variable orifice geometry has long been common knowledge in the area of engine construction. But up to...

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Bibliographic Details
Published in:SAE transactions 1995-01, Vol.104, p.154-164
Main Authors: Potz, Detlev, Kreh, Andreas, Warga, Johann
Format: Article
Language:English
Subjects:
Combustion
Combustion chambers
Cylinders
Engine design
Engines
Geometry
Injections
Low speed
Nozzles
Smoke
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Summary:Innovative solutions for reducing particulate emissions will be necessary in order to comply with the even more stringent exhaust-gas standards of the future. The potential of a diesel nozzle with variable orifice geometry has long been common knowledge in the area of engine construction. But up to now, a fully functional solution of such a nozzle has not appeared which operates with a reduced orifice at low engine speeds and/or low loads. Here with regard to target costing, the requirements implicit in function and manufacture must also be taken into account. Using calculations on nozzle interior flow and injection-spray investigations, it will be shown which nozzle geometries best fulfill the various requirements. In order to achieve low levels of particulate emission in an engine with a combustion chamber designed for optimum use of a hole-type nozzle, the injection-spray direction and its geometry must to a large extent correspond to those of a hole-type nozzle. This is decisive for the two-phase nozzle (VRD) to make full use of its potential in a conventional combustion chamber. The two-phase nozzle with spray orifices arranged directly above one another provides the solution to this problem. The spray geometry for the variable-orifice nozzle has been realised. The application of the needle control for the FTP75 test procedure is being worked on.
ISSN:0096-736X
2577-1531