Development and Evaporation of Group-Hole Nozzle Sprays under Various Surrounding and Impinging Conditions of Direct-Injection Diesel Engines

Abstract

In the present study, penetration and evaporation of the diesel sprays injected by a group of two closely spaced orifices (a group-hole nozzle) were investigated and compared with those of conventional single-hole nozzle sprays under various engine loads and wall-impinging conditions of direct-injection (DI) diesel engines. Both free and wall-impinging conditions were considered. The experiments were performed inside a constant-volume vessel under simulated ambient conditions for low and high engine loads of DI diesel engines. To investigate the effect of spray targeting, two impinging conditions (impingement angles of 45° and 90° with the same impingement distance) were applied. Geometry and liquid/vapour mass distributions of the evaporating diesel sprays were analysed using a laser absorption scattering (LAS) technique. Under a free spray condition, fuel evaporation of the group-hole nozzle spray was improved compared with that of the single-hole nozzle spray at low load conditions, while it showed simultaneous deterioration in fuel evaporation and spray tip penetration at high load conditions. Jet axes deflection of the two jets from the group-hole nozzle, which generated a dense liquid region at the central region of the spray, was responsible for this deteriorated evaporation at high load conditions. Under a vertical impingement condition (impingement angle of 90°), the group-hole nozzle spray showed simultaneous improvement in spray tip penetration and fuel evaporation at both low and high load conditions from strong momentum interaction of the two jets on the impingement wall. However, this improvement from the group-hole nozzle did not appear at an inclined wall-impingement condition (impingement angle of 45°) owing to weakened and delayed momentum interaction of the two jets. Both spray tip penetration and fuel evaporation of the group-hole nozzle spray were deteriorated at the inclined wall-impinging condition.

Spray measurement technology: a review

“…These parameters usually cannot be extracted quantitatively, although with simultaneously recorded Miescattering data to mark the liquid, one can determine liquidand vapor-phase envelopes from schlieren images [46,47]. The laser absorption and scattering (LAS) technique measures line-of-sight-integrated liquid and vapor mass distributions using back-illumination imaging at two laser wavelengths, only one of which is absorbed appreciably [48][49][50]. With the assumption of axisymmetry or with images taken from several angles (typically ~10 or more), tomographic inversion of lineof-sight images can yield a 3D representation of the measured quantity.…”

“…For averaged data, one can stack a series of planar LIF, LIEF, Mie-scattering or PIV results [84,117]. Tomographic inversion of line-of-sight data (nearly always on an average rather than an instantaneous basis) is another approach [34, [50][51][52][53][54]154]. Holography has been used with some success [2,155,156], particularly with large-diameter (~10 mm) nozzles [157][158][159][160][161], but the need to resolve individual droplets requires high resolution, and the interrogation procedures are often very demanding of human and computer resources [162].…”

“…Planar Mie scattering (figure 3(a)), LIF and LIEF are effective to visualize the near-wall liquid-and vapor-phase distributions [113,[274][275][276]280], and PDS has been applied for near-wall droplet-size measurement [281]. Line-of-sight-integrated near-wall liquid and vapor mass distributions have been measured by LAS [50]. Two-wavelength PLIF has been used for near-wall droplet temperature [282], while molecular tagging thermometry based on phosphorescence lifetime has been used to measure surface droplet temperature and size [283].…”

Experimental Studies of Emissions in a CI Engine Blended with Refined Palmolein Oil

“…This could be a good alternative fuel for diesel. Natraj.M, et, al, [11] conducted an experiment by varying the design parameters of the DI, 4S, diesel engine like Nozzle spray hole, Piston head clearance, Nozzle protrusion, Starting of injection timing, Injection control pressure, Swirl level. By varying these parameters, the emissions were reduced and analyzed by taguchi method.…”

Particle and Gas Flow Modeling of Wall-impinging Diesel Spray under Ultra-high Fuel Injection Pressures

“…They used micro-hole nozzle under ultra-high injection pressures. Also, penetration and evaporation of the diesel sprays injected through a group-hole nozzle with conventional single-hole nozzle sprays have been experimentally compared by Moon et al (2011). They used various engine loads and wall impinging conditions of direct injection diesel engines.…”