Effect of High Injection Pressures and Ambient Gas Properties Over the Macroscopic Characteristics of the Diesel Spray on Multi-Hole Nozzles

Abstract

In this work, the effect of high injection pressures and ambient gas properties on diesel spray penetration and spreading angle are studied. To this end a multi-hole piezoelectric injector was used, and MIE-Scattering optical technique to visualize the spray. Injection pressures up to 270 MPa were used throughout the experiments. Additionally, the spray behavior going from subsonic to supersonic state was analyzed by controlling the ambient gas speed of sound, promoting in this way supersonic jets. For this purpose, measurements were done using three different ambient gases (SF 6 , CO 2 , and N 2) at isothermal conditions. The results showed that sprays near transonic or in supersonic state had a higher penetration rate than those in subsonic state. Furthermore, among the sprays near transonic or in supersonic state, those with higher Mach number had faster penetration. Differently, within the sprays at subsonic state, no significant variations in spray penetration rate were found, regardless of the difference in the Mach number. Shock waves appearances were pointed out as a possible explanation for the spray penetration variations observed. Finally, a statistical analysis is presented for the spray penetration under isothermal conditions and for each ambient gas.

ECN Spray D visualization of the spray interaction with a transparent wall under engine-like conditions. Part I: Non-reactive impinging spray

“…From a comparison between le and right sets of images it can be seen how n-dodecane penetration is consistently faster than for diesel. A possible explanation to that comes from spray theory: Many models for free penetration describe an e ect of internal ow [45,35,47]. Taking Naber et.…”

Experimental investigation on effect of gas/spray interactions on transient diesel spray behaviors

“…Lower r ambient and the resultant resistance at the spray tip can be obtained after the detachment of shock waves. [24][25][26] Giraldo et al 28 reported that the sprays near transonic or in supersonic state had a higher penetration rate than those in subsonic state, where no significant difference was found in the penetration length as the ambient gas species varied.…”

Effects of fuel injection parameters on premixed charge compression ignition combustion and emission characteristics in a medium-duty compression ignition diesel engine

“…The low volatility of the diesel fuel implies the requirement of high injection pressure strategies with different exhaust gas recirculation (EGR) rates to promote the PCCI combustion. 17,18 In this sense, high injection pressures 19 and high swirl ratios promote a better air–fuel mixing process, generating sufficient premixing time between SoC and EoI (end of injection) to achieve an efficient PCCI combustion. 20 Initially, a single-stage direct injection of fuel was used to achieve the PCCI combustion, where the early direct injection during the compression stroke favored the air–fuel mixture because of the presence of a higher in-cylinder temperature and longer mixing time.…”