Spray Formation from Spark-Eroded and Laser-Drilled Injectors for DISI Engines with Gasoline and Alcohol Fuels

Abstract

One of the latest advancements in injector technology is laser drilling of the nozzle holes. In this context, the spray formation and atomisation characteristics of gasoline, ethanol and 1-butanol were investigated for a 7-hole spark eroded (SE) injector and its 'direct replacement' Laser-drilled (LD) injector using optical techniques. In the first step of the optical investigation, high-speed spray imaging was performed in a quiescent injection chamber with global illumination using diffused Laser light. The images were statistically analyzed to obtain spray penetration, spray tip velocity and spray 'cone' angles. Furthermore, droplet sizing was undertaken using Phase Doppler Anemometry (PDA). A single spray plume was isolated for this analysis and measurements were obtained across the plume at a fixed distance from the nozzle exit. The droplet measurements were grouped into bins and maps were created showing droplet sizes and velocities against time and position during and post injection. All tests were performed at 120 bar fuel pressure, two injection chamber 'back' pressures (0.5 bar and 1 bar) and two injector temperatures (20 °C and 80 °C), to examine effects relevant to typical engine operating conditions with early intake stroke injection strategies, including fuel flash boiling.

Modulation of integral length scales of turbulence in an optical SI engine by direct injection of gasoline, iso -octane, ethanol and butanol fuels

“…with this injection system but also a range of other injectors [20][21][22]. When averaging was applied in y-direction to obtain the mean length scales along the x-axis (Figure 21), L u still showed little spread between fuels with values typically between 3-4 mm, reducing to 1 mm closer to the cylinder head at x=-14 mm.…”

“…Iso-octane is one of the major single components of gasoline, with a boiling point of 99 °C at atmospheric pressure; n-butanol boils at 117 °C whilst ethanol boils at 78.4 °C. Table 2 provides a quick overview of various thermophysical properties of these fuels; the distillation curve of the specific gasoline used has been shown elsewhere [20][21]. A single-hole swirl-type DI injector was mounted on the intake side of the combustion chamber between the two intake valves.…”

Developing Low Gasoline Particulate Emission Engines Through Improved Fuel Delivery

“…Spray data using EN228 RON95 fuel is shown here. A full description of the measurement techniques used as well as more results can be found in Behringer et.al [6]. The injectors were tested in a clean condition to enable direct comparison.…”

“…The laser drilled nozzle also has a degree of taper. Full nozzle dimensions are given in [6]. The injector sprays were then fully characterised using optical techniques.…”

Flame front analysis of ethanol, butanol, iso-octane and gasoline in a spark-ignition engine using laser tomography and integral length scale measurements

“…Iso-octane is one of the major single components of gasoline, with a boiling point of 99 °C at atmospheric pressure; nbutanol boils at 117 °C whilst ethanol boils at 78.4 °C. Table 1 provides a quick overview of various thermophysical properties of these fuels; the distillation curve of the specific gasoline used has been shown elsewhere [56,57]. Summarising published data, Aleiferis et al [51] tabulated laminar burning velocities at =1.0 and =0.5 for these fuels at pressure and temperature conditions relevant to those expected at the start of combustion in SI engines.…”