“Spray A” and “Spray B” Operating Condition
The ECN working group has identified a few experimental conditions that will be the focus of modelers and experimentalists who wish to voluntarily participate in the ECN in the future. The experimental collaboration is made possible by the donation of “identical” injection systems by Robert Bosch LLC. The ECN group has agreed to experiment at the same injector and ambient conditions, thereby leveraging the expertise of each participant, and enabling direct comparison between different facilities. We expect that the data set developed will become a serious focal point for model validation and further advanced diagnostics.
Specifications for the injector and ambient operating conditions for this “Spray A” condition are given below but recommendations for parametric variation beyond Spray A are also available. The operating conditions below can also be used for Spray B. The Spray A condition is a low-temperature combustion condition relevant to engines that use moderate EGR. The injector specifications are for modern advanced injection systems with high pressure capability. As a prerequisite to using these injectors, ECN participants are expected to measure the boundary conditions (e.g. temperature, pressure) for the ambient and injector quantities, and state uncertainties associated with the boundary conditions and other data. Please contact Lyle Pickett if you believe you can meet these boundary conditions and would like to use one of the shared injectors. Also see requirements to care/handle the injectors.
If seeking to match only the injector specifications while operating at room temperature for the ambient gases, care should be taken to match the ambient density specification, as this primarily determines the spray mixing and penetration rate.
| Specifications for Spray A operating condition of the Engine Combustion Networka | |
| Ambient gas temperature | 900 K |
| Ambient gas pressureb | near 6.0 MPa |
| Ambient gas densityb | 22.8 kg/m3 |
| Ambient gas oxygen (by volume) | 15% O2 (reacting); 0% O2 (non-reacting). (look here for CO2 and H2O and N2 %) |
| Ambient gas velocity | Near-quiescent, less than 1 m/s |
| Common rail fuel injector | Bosch solenoid-activated, generation 2.4 |
| Fuel injector nominal nozzle outlet diameter | 0.090 mm |
| Nozzle K factor | K = (dinlet – doutlet)/10 [use μm] = 1.5 |
| Nozzle shaping | Hydro-eroded |
| Mini-sac volume | 0.2 mm3 |
| Discharge coefficient | Cd = 0.86, using 10 MPa pressure drop and diesel fuel |
| Number of holes | 1 (single hole) |
| Orifice orientation | Axial (0° full included angle) |
| Fuel injection pressure | 150 MPa (1500 bar), prior to start of injection |
| Fuel | n-dodecanec |
| Fuel temperature at nozzled | 363 K (90°C) |
| Common raile | GM Part number 97303659. Used by 2005-2006 Duramax engines. |
| Common rail volume/length | 22 cm3/28 cm |
| Distance from injector inlet to common rail | 24 cm |
| Tubing inside and outside diametersf | Inside: 2.4 mm. Outside: 6-6.4 mm. |
| Fuel pressure measurement | 7 cm from injector inlet / 24 cm from nozzle |
| Injection duration | 1.5 ms |
| Injection mass | 3.5 – 3.7 mg |
| Approximate injector driver current | 18 A for 0.45 ms ramp, 12 A for 0.345 ms hold |
| Access experimental data | Click for Spray A experimental data search |
a from SAE Paper 2010-01-2106 (Link)
b This exact combination of ambient pressure and density corresponds to a particular set of gases for a 0%-O2 condition with 89.71% N2, 6.52% CO2, and 3.77% H2O by volume and a compressibility factor, Z = 1.01. When different gases are used, the pressure must vary to maintain the same density
c Chosen as a fluorescence-free diagnostics fuel with known chemistry and properties. Other fuels may be selected after initial study and comparison.
d Measured upstream of the orifice, at the time that injection would take place, see SAE Paper 2010-01-2106 (Link). May be slightly different than injector body temperature, and different than the steady state temperature.
e Use rail outlet farthest away from fuel entrance (small orifice) to rail (i.e. cylinder #1).
f This 24 cm tube is available for purchase from USUI, reference part number IFP1. It is rated for 2500 bar.