Ultra-Fast X-Ray Radiography for the Study of Fuel Sprays U.S. Department of Energy, Energy Efficiency and Renewable Energy Vehicle Technologies Program Gurpreet Singh, ACEC Team Leader Christopher Powell, Alan Kastengren Center for Transportation Research Jin Wang, Kyoung-Su Im Advanced Photon Source

Why Use X-Rays to Study Sprays? Scattering is difficult to interpret Number of x-rays absorbed indicates the quantity of fuel. Visible Light Imaging X-Ray Radiography

The Advanced Photon Source

Schematic of X-Ray Setup I0I0 I I 0 Incident x-ray intensity I Measured x-ray intensity  M Fuel absorption constant M Mass of fuel in x-ray beam Direct relation between x-ray intensity and fuel mass

X-Ray Detectors 1.Cornell Pixel Array Detector  Fast (100 ns) 2D imaging  Marginal spatial resolution (150  m)  Expensive prototype, limited access  Susceptible to radiation damage (lifetime about 5 days) 2.Avalanche Photodiode  Fast (1 ns), robust, inexpensive  Zero-D, must raster to form image. Tedious  Enables excellent spatial resolution (15  m)  Continuous readout, captures complete time history

Time History of X-Ray Flux 0.2 mm from Nozzle Spray Enters Beam Spray Leaves Beam

Typical Measurement Grid

The Effects of Nozzle Geometry

9 Recent Accomplishments Development of technique to measure fuel average speed –Previous measurements at leading and trailing edges –“Internal” fuel speed as a function of time Single-shot measurements of spray –Previous measurements were all averaged Measurements of Caterpillar HEUI injector –Production 6-hole nozzle Measurements of biofuel sprays

Measurement of Fuel Velocity Internal fuel velocity affects penetration, atomization, exchange of momentum with ambient gas Accurate measurement crucial for numerical modeling –Exit velocity may be useful in validating models of flow inside the orifice –Need spray velocity for spray breakup models Dynamic measurements of velocity would be particularly useful –How does spray velocity change as the needle opens/closes? Existing techniques are limited: –Discharge coefficient, laser two-focus, laser flow tagging, LDV/PDPA –Ballistic imaging –All are limited near-nozzle or don’t provide transient measurement

Average Fuel Speed Found by Control Volume Analysis Injector Spray Control Volume Fuel enters only from left side, doesn’t exit We have time-dependent measurement of quantity of fuel (M 1, M 2,…) –Can determine mass flux M 2 - M 1 / t 2 - t 1 We measure quantity of fuel in slice through spray, mass/thickness

12 Measurement of Fuel Speed Speed of fuel emerging from nozzle increases over time as needle opens and pressure at orifice increases Fuel speed is highest when it emerges from nozzle, slows as it moves downstream Fuel speed crucial for spray modeling –Relates to exchange of momentum with ambient gas –Both KH and RT atomization models rely on this quantity Speed At Nozzle Exit 33  s After SOI

Measurement of Instantaneous Fuel Speed Two nozzles show similar speeds Early in spray event, needle may not be fully open

14 Single-Shot Measurements - Repeatability of Start of Injection 2 mm from nozzle, 500 bar

15 Single-Shot Measurements - Repeatability of End of Injection 0.2 mm from nozzle, 500 bar

Measurements of Caterpillar Heavy-Duty HEUI Injector Goal: Link spray measurements with engine performance –Measure sprays under “engine-like” conditions. Vary injection pressure, nozzle geometry. –Measure how changes in spray affect engine performance 6-hole production nozzle Utilizes Argonne’s strengths in engine measurement: performance, in-cylinder imaging, emissions. Requires modeling to link spray measurements with engine data

CAT HEUI Injector Operating at APS 17

18 Caterpillar HEUI Injector

Near Nozzle Spray Penetration Speed is Slow 19 Slower penetration speeds observed than with Bosch Common Rail systems Further data analysis is ongoing Engine will be running before the end of the year Ambient density and fuel delivery will be matched between x-ray and engine measurements Spray and Engine modeling work is beginning.

Alternative Choices for Transportation Fuel Ethanol Low energy content Lower viscosity, lubricity Bio-Diesel Fewer aromatics, more esters Higher viscosity, lubricity Vegetable Oils Very high viscosity Short shelf life, acid content Hydrogen Generation & storage Consumer perception  Each fuel is expected to gain market share  Engine must adapt to optimize performance and meet emissions for a variety of fuels  What are the effects on sprays?

Fuel Distribution Comparison, B50 and Viscor 21

Average Fuel Speed Comparison, B50 and Viscor 22

Experiment Parameter Matrices 23 1 bar He7 bar He1 bar N214 bar He2 bar N21 bar SF65 bar N210 bar N215 bar N220 bar N230 bar N2 250 bar, 400 usBosch 18 Bosch 22: Different Break I 250 bar, 1000 usBosch bar, 400 usBosch 18 Bosch 12 Bosch 12 Bosch 13 Bosch 15: mm Bosch 26: mm 500 bar, 1000 usBosch 19 Bosch 23: mm, sparse, 0 and 90 deg. rotation Bosch 26: mm 1000 bar, 400 usBosch 18 Bosch 13 Bosch 15: mm, pressure fluctuations Bosch 26: mm 1000 bar, 1000 usBosch 19Bosch 20Bosch 19 Bosch 20 Bosch 26: mm Bosch 26: mm 1 bar He7 bar He1 bar N214 bar He2 bar N21 bar SF65 bar N210 bar N215 bar N220 bar N230 bar N2 250 bar, 400 us Bosch19 Bosch bar, 1000 us Bosch bar, 400 usBosch 19 Bosch 13 Bosch 15: mmBosch 15: mm Bosch 15: 0.2 and 1.0 mm; Bosch 25: 0.2 mm 500 bar, 1000 usBosch 19 Bosch 25: mm Bosch 20: mm Bosch 25: mm Bosch 26: mm Bosch 26: mm Bosch 26: mm Bosch 26 SS: 0.2, 2.0, 4.0 mm 1000 bar, 400 usBosch 19Bosch 24Bosch 13 Bosch 15: mm Bosch 24Bosch 25: mmBosch 26: mm 1000 bar, 1000 usBosch 19Bosch 20 Bosch 24 Bosch 25: mmBosch 20: mmBosch 24Bosch 25: mm Bosch 24 Bosch 26: mm Non-Ground HydroGround

24 Experiment Conditions Simulate an Operating Engine Measurements at ambient pressure of 30 bar are now routine Gas density inside the spray chamber exceeds that of a light-duty diesel at TDC Long-term tests of x-ray pressure windows shows they are capable of further pressure increase Crank Angle Degrees Ambient Density (kg/m 3 ) (Mercedes 1.7L, 9 psi boost) Ambient Density (kg/m 3 ) (CAT 3406E, 23 psi boost) Ambient Pressure (bar) Ambient Density (kg/m 3 ) (300K) X-Ray Experiments Light-DutyHeavy-Duty

25 Future Plans Measurements of Caterpillar injector have demonstrated feasibility of using production 6-hole injectors –Build adapter to mount 3- and 6-hole Bosch Injectors in Caterpillar chamber –Shield to isolate spray of interest Update fuel system to accommodate Bosch Generation 2 and 3 injectors –Use hardware common to GM-Fiat 1.9 liter –Study conditions that match in-cylinder density, injection pressure –Engine is running at Argonne, other labs also have this engine –Will enable direct comparison between x-ray measurements and Argonne’s full suite of engine diagnostics: in-cylinder imaging, emissions, performance.

26 Presentations and Publications, FY2007 “Measurement Of Diesel Spray Axial Velocity X-ray Radiography”, Alan Kastengren, Advanced Engine Combustion MOU Meeting, February 2007, SNL. “Fuel Spray Characterization Using Ultra-Fast X-Ray Radiography”, Christopher Powell, UIC Mechanical Engineering Graduate Council, March 2007, Chicago, IL. “Determination of Diesel Spray Axial Velocity Using X-Ray Radiography”, Alan Kastengren, SAE Congress, April 2007, Detroit, MI. “Improved Method to Determine Spray Axial Velocity Using X-Ray Radiography”, Alan Kastengren, ILASS, May 2007, Chicago, IL. “Structure Of High-velocity Dense Sprays In The Near-Nozzle Region” F. X. Tanner, K. A. Feigl, S. A. Ciatti, C. F. Powell, S.-K. Cheong, J. Liu, J. Wang, Atomization and Sprays , “Determination of Diesel Spray Axial Velocity Using X-Ray Radiography”, Alan Kastengren, SAE Congress, April 2007, Detroit, MI. “Improved Method to Determine Spray Axial Velocity Using X-Ray Radiography”, Alan Kastengren, ILASS, May 2007, Chicago, IL. “Spray Density Measurements Using X-Ray Radiography”, A. L. Kastengren and C. F. Powell, J. Auto. Eng. Special Edition. Accepted for publication. “X-Ray Measurements of the Mass Distribution in the Dense Primary Break-Up Region of the Spray from a Standard Multi-Hole Common-Rail Diesel Injection System”, P. Leick, T. Riedel et al., ILASS- Europe, Sep 2007, Muğla, Turkey. “Nozzle Geometry and Injection Duration Effects on Diesel Sprays Measured by X-Ray Radiography”, A.L. Kastengren et al., Submitted to J. Fluids Eng. “Study Of Diesel Jet Variability Using Single-shot X-ray Radiography”, A. L. Kastengren, C. F. Powell, Y. Wang, J. Wang, Submitted to ASME.