Influence of injector technology on injection and combustion development – Part 1: Hydraulic characterization

Abstract

An experimental study of two real multi-hole Diesel injectors is performed under current DI Diesel engine operating conditions. The aim of the investigation is to study the influence of injector technology on the flow at the nozzle exit and to analyse its effect on the spray in evaporative conditions and combustion development. The injectors used are two of the most common technologies used nowadays: solenoid and piezoelectric. The nozzle for both injectors is very similar since the objective of the work is the understanding of the influence of the injector technology on spray characteristics for a given nozzle geometry. In the first part of the study, experimental measurements of hydraulic characterization have been analyzed for both systems. Analysis of spray behavior in evaporative conditions and combustion development will be carried out in the second part of the work. Important differences between both injectors have been observed, especially in their transient opening and closing of the needle, leading to a more efficient air-fuel mixing and combustion processes for the piezoelectric actuated injector.

Fuel temperature influence on diesel sprays in inert and reacting conditions

“… Future works should be addressed to the understanding of eventual fuel temperature variation taking place during the expansion in the orifice: the authors consider that the fuel expansion (the fuel cannot be considered incompressible at pressures over 100 MPa) and the fluid friction with the orifice's walls can cause further variation in the fuel temperature. Tables Table 1: Test conditions summary 1 The injector temperature T f = 343 K has been used only in liquid length tests 2 The ambient density T g = 7.6 kg/m 3 been used only in liquid length tests 3 The 0% O2 concentration has been employed in liquid length test and 15% in the lift-off length test Table 2: Fuel temperature estimated for all the conditions tested. The temperature has been obtained averaging the temperature of the injector measured in the first 3 mm from the injector tip Table 3: Exponents obtained by the regression with equation (4) to LL results.…”

“…The results of the analysis are shown in Table 5. It has to be noticed that the 2 R calculated in the regression presents an important discrepancy: this fact is not surprising as long the parameter A is dependent also on the activation energy that is dependent on the fuel employed and in [3][4][1] a different fuel has been used (Repsol CEC RF-06-99 instead of n-dodecane). Apart from this difference, it is important to note that keeping the other coefficient and adjusting the dependence on the fuel temperature, the R 2 found is very high (98,8%).…”

Study liquid length penetration results obtained with a direct acting piezo electric injector

“…The system allows fuel injections at high and relatively constant pressure (up to 200 MPa) [22][23] [26]. All the injection system is electronically controlled by the ECU and all the settings are introduced digitally.…”

Needle lift profile influence on the vapor phase penetration for a prototype diesel direct acting piezoelectric injector

“…It is constituted by a high pressure pump and a conventional rail with an electronic pressure regulator, which allows fuel injections under high (up to 200 MPa) and constant rail pressure [2][3] [11]. The injector temperature was kept close to 343K using a special injector holder designed to have coolant flowing at a controlled temperature in direct contact with the injector body.…”