F2008-06-005
Experimental and Simulated Determination of the Injection Characteristic
Experimental and simulated determination of the injection characteristic
Author: János Kerékgyártó - Otto-von-Guericke-University Magdeburg Lothar Schulze - Otto-von-Guericke-University Magdeburg Helmut Tschöke - Otto-von-Guericke-University Magdeburg
Abstract The combustion´s quality, the noise- and exhaust emissions in diesel engines will be affected by the characteristic of the injection. This paper reports on the results of a new method for measuring the injection´s characteristic of a modern diesel high-pressure fuel injection system developed at the Institute of Mobile Systems at Otto-von-Guericke-University Magdeburg. The results of the experimental method will be supported and verified by comparison with detailed and comprehensive simulations from 1D-CFD-code AMESim. A direct measurement of the injection characteristic in the engine is still not possible. The available measuring systems measure the injection characteristic outside of the engine. The verification of these measuring equipments with a so-termed master instrument has not been realized so far. Hence an instrument was developed, that generates a defined, precise mesurable "injection characteristic", that serves as an input for the connected measuring equipment. Simulation and experiment approve, that in this instrument a deterministic injection characteristic (near injection fuel flow) can be generated by a measured piston movement in the measuring cylinder. The piston movement will be recorded with an inductive displacement sensor and the generated injection characteristic can be calculated from the product of piston movement and piston cross?sectional area. This amount of fuel can be supplied in the direct coupled injection characteristic´s measuring equipment. This permits a comparison between input (with instrument measured injection characteristic) and output (with conventional measuring equipment measured injection characteristic). On the one hand the deviation of the measuring equipment can be defined by this comparison. On the other hand a correction coefficient can be detected for the measuring equipments available on the market. It is important to understand how behave the fluid in the conventional measuring equipment during the injection. The influence of the injection´s dynamically run has to been investigated in the fluid. Beside pressure wave appear a resistance of the fluid too. This resistance can generate a measurement failure of the conventional measuring equipment. On that score this effect will be simulated mechanically in all working point with the 1D-CFD-code AMESim. Through this simulation a backward calculation of the resistance´s influence can be realized. Therewith a correction of measuring results of conventional measuring equipment can be calculated without any simulation.
Contact: János Kerékgyartó University Magdeburg Institute of Mobile Systems Department of Combustion Engines Building.14/122 Tel:+49 391 / 67-12831 Fax:+49 391 / 67-12832 E-mail: janos.kerekgyarto@st.ovgu.de
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Session: Fuel Injection II