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The study of the spray of standard, five-hole, V.C.O. nozzles for D.I. diesel engine has been carried out. Several pictures of the spray have been taken using the back-light photography technique. Injected volume, feeding pressure, injection duration, spray penetration, angle and thickness, and flash delay from the start of injection have been measured both for nozzles of two different manufacturers and for a group of four injectors before and after a fatigue test of about 1500 hours running. Measurements revealed that each spray strongly depends on the needle lift, the back-pressure and the nozzle geometry and that, for the same injector, sprays are totally different from hole to hole. The causes of the most important differences have been attributed at the different hole inclination, their asymmetric feeding conditions (due to the eccentricity between needle and nozzle) and the microdefects caused by drilling operation.

The spray of a 5-hole, V.C.O. nozzle for D.I. diesel engines has been studied; the data obtained from each hole were compared. A high pressure injection system (Elasis patent), electronically controlled, was used. To investigate the behaviour of each hole a “cap” was used to cover the nozzle in such a way that only one hole at a time could inject in the spray chamber. The investigation consisted of a photographic characterization with back-light technique and of the droplet size distribution through laser diffraction technique via Malvern. Four pressure values (30, 60, 90, 120 MPa) and three injected flowrates (10, 25, 40 mm3/inj.) were chosen to characterize the behaviour of the nozzle. Each test was carried out with the nozzle under normal running conditions, measuring the laser signal background after each acquisition.

An axi-symmetric, five-hole V.C.O. nozzle mounted on an electro-injector was used to analyze the spray produced by each hole varying feeding pressure, injected quantity and timing. An advanced experimental apparatus has been used to investigate particle size and velocity of the sprays. The investigation comprized a hydraulic characterization, a photographic one with back-light technique, the analysis of the droplet size distribution through laser diffraction technique via MALVERN 2600 SERIES and the analysis of particle size and velocity using PDPA technique (AERMETRICS DSA 4000) with the extremely dense spray produced by the common-rail electronically controlled injection system. Four feeding pressures (25, 30, 90, 120 MPa) and five injected quantities (2, 4, 10, 25, 40 mm3/shot) were chosen to characterize the nozzle behavior. Sprays from different holes appeared different in shape but very similar in the droplet size distribution.

A simulation code of an innovative electro-injector for Diesel engines is presented with the preliminary analysis carried out using the code. The simulation code is based on the concentrated volume method. The energy and continuity conservation equations and dynamic equations are used for the movable parts of the system under friction. The one dimensional code simulated the propagation in the feeding pump and the control of the electro-injector. The program uses the method of characteristics to solve conservation equations, simulating the propagation in the pipe between the two chambers. To go deeply into the study of the electro-injector, main routine tests were carried out checking the exact value of diesel fuel parameters and the fuel energy losses with stationary and instationary flows. A comparison with different experimental results obtained by different types of electroinjectors, running at real conditions, has been made with good agreement.