Effect of needle profile in the ICE fuel injector nozzle on the quality of fuel atomisation

Description

The results of research on the impact of changing the cross-section of the atomizer's flow channel caused by changing the flow geometry of the (passive) part of the needle on the granulometric distribution of the fuel aerosol formed during its atomization in a medium under atmospheric pressure. Diesel oil without biocomponents (D100) was used in the study. During the measurements, the temperature of the fuel and air into which the injection was carried out was 20 °C. Three-hole type H1LMK 148/1 atomizer with hole diameter dN equal to 0.34 mm was analyzed. The fuel injector was installed on the measuring stand and powered by a fuel pump with a constant fuel dose of 0.6 cm3 set for all measurements. A nozzle with a standard (unmodified) needle and three nozzles with needles with a modified profile in the flow part of the needle, marked with the code signatures 1L, 2L and 3L, were tested. The needles are characterized by an increasing level of fuel turbulence during its flow along the flow part due to the use of one (1L), two (2L) and three (3L) de Laval toroidal nozzles, respectively, obtained by mechanically shaping the outer surface of the flow part of the spray needle. The injectors were adjusted to the standard injector opening pressure of 26 MPa. The aerosol produced was tested using the Malvern Spraytec STP 500 device cooperating with the dedicated Malvern ver. 4.0. During the tests, measurements and analysis of the aerosol droplet size distribution over the entire duration of injection, equal to 7±2 ms, were made for each of the nozzles. The experiment made it possible to determine the effect of nozzle needle profiles on the time distribution of actual droplet diameters, the time distribution of Sauter mean droplet diameters D[3,2], percentile shares of droplet diameters Dv(10), Dv(50) and Dv(90), distibution span over time the development of the aerosol stream and the time distribution of the share of drops with diameters belonging to the selected diameter classes D[x1-x2] in the aerosol. The results of measurements of the granulometric distribution indicate that the use of atomizers with a modification of the flow channel allows for an increase in the share of droplets with smaller diameters compared to the standard atomizer.

Steps to reproduce

During the tests, measurements and analysis of the aerosol droplet size distribution over the entire duration of injection, equal to 7±2 ms, were made for each of the nozzles. The experiment made it possible to determine the effect of nozzle needle profiles on the time distribution of actual droplet diameters, the time distribution of Sauter mean droplet diameters D[3,2], percentile shares of droplet diameters Dv(10), Dv(50) and Dv(90), distibution span over time the development of the aerosol stream and the time distribution of the share of drops with diameters belonging to the selected diameter classes D[x1-x2] in the aerosol. The results of measurements of the granulometric distribution indicate that the use of atomizers with a modification of the flow channel allows for an increase in the share of droplets with smaller diameters compared to the standard atomizer.

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