Nozzle Geometry and Injection Duration Effects on Diesel Sprays Measured by X-Ray Radiography

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
A. L. Kastengren ◽  
C. F. Powell ◽  
T. Riedel ◽  
S.-K. Cheong ◽  
K.-S. Im ◽  
...  
Keyword(s):  
Ambient Pressure ◽  
Injection Pressure ◽  
Leading Edge ◽  
Nozzle Geometry ◽  
Diesel Sprays ◽  
X Ray ◽  
Injection Duration ◽  
Quantitative Measurements ◽  
Light Duty ◽  
Trailing Edges

X-ray radiography was used to measure the behavior of four fuel sprays from a light-duty common-rail diesel injector. The sprays were at 250bar injection pressure and 1bar ambient pressure. Injection durations of 400μs and 1000μs were tested, as were axial single-hole nozzles with hydroground and nonhydroground geometries. The X-ray data provide quantitative measurements of the internal mass distribution of the spray, including near the injector orifice. Such measurements are not possible with optical diagnostics. The 400μs sprays from the hydroground and nonhydroground nozzles appear qualitatively similar. The 1000μs spray from the nonhydroground nozzle has a relatively consistent moderate width, while that from the hydroground nozzle is quite wide before transitioning into a narrow jet. The positions of the leading- and trailing-edges of the spray have also been determined, as has the amount of fuel residing in a concentrated structure near the leading edge of the spray.

Measurement of Biodiesel Blend and Conventional Diesel Spray Structure Using X-Ray Radiography

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
A. L. Kastengren ◽  
C. F. Powell ◽  
K.-S. Im ◽  
Y.-J. Wang ◽  
J. Wang
Keyword(s):  
Cone Angle ◽  
Injection Pressure ◽  
Fuel Distribution ◽  
X Ray ◽  
Spray Structure ◽  
Quantitative Measurements ◽  
Biodiesel Blend ◽  
Temporal And Spatial ◽  
Nozzle Geometries ◽  
Fuel Effects

The near-nozzle structure of several nonevaporating biodiesel-blend sprays has been studied using X-ray radiography. Radiography allows quantitative measurements of the fuel distribution in sprays to be made with high temporal and spatial resolution. Measurements have been made at different values of injection pressure, ambient density, and with two different nozzle geometries to understand the influences of these parameters on the spray structure of the biodiesel blend. These measurements have been compared with corresponding measurements of Viscor, a diesel calibration fluid, to demonstrate the fuel effects on the spray structure. Generally, the biodiesel-blend spray has a similar structure to the spray of Viscor. For the nonhydroground nozzle used in this study, the biodiesel-blend spray has a slightly slower penetration into the ambient gas than the Viscor spray. The cone angle of the biodiesel-blend spray is generally smaller than that of the Viscor spray, indicating that the biodiesel-blend spray is denser than the Viscor spray. For the hydroground nozzle, both fuels produce sprays with initially wide cone angles that transition to narrow sprays during the steady-state portion of the injection event. These variations in cone angle with time occur later for the biodiesel-blend spray than for the Viscor spray, indicating that the dynamics of the injector needle as it opens are somewhat different for the two fuels.

Comparison Between a Center-Mounted and a Side-Mounted Injector for Gasoline Applications: A Computational Study

2020 ◽  
Author(s):  
Lorenzo Nocivelli ◽  
Anqi Zhang ◽  
Brandon A. Sforzo ◽  
Aniket Tekawade ◽  
Alexander K. Voice ◽  
...  
Keyword(s):  
Best Practice ◽  
Computational Study ◽  
Ambient Pressure ◽  
Near Field ◽  
Cone Angle ◽  
Injection Pressure ◽  
Operating Conditions ◽  
Gasoline Direct Injection ◽  
X Ray ◽  
Fuel Density

Abstract The differences between a center-mounted and a side-mounted injector for gasoline direct injection (GDI) applications are analyzed through computational fluid dynamics (CFD). The Engine Combustion Network’s (ECN) axisymmetric 8-hole Spray G injector is compared to a 6-hole injector designed to be side-mounted in an engine. Nozzle-flow simulations are carried out with the commercial CFD software CONVERGE, injecting Euro 5 certification gasoline into a constant volume chamber. Low-load operating conditions are targeted, setting the injection pressure at 50 bar and the ambient pressure to be representative of very early pilot injections. The phase change is handled with the Homogeneous Relaxation Model (HRM), which is assessed and adapted to gasoline flash-boiling conditions. The simulation domains are generated leveraging real injector internal geometries obtained by micron-resolution X-ray tomographic measurements, which introduce manufacturing tolerances and surface roughness in the computational study. Steady needle lift conditions are analyzed. The near-field fuel density distributions and plume morphologies are evaluated, validated and compared to X-ray radiography measurements. A computational best practice is defined and single plume characteristics and variability trends are highlighted as functions of the geometry of the orifices. The plume-plume interaction dynamics are identified and assessed, underlining differences from center- to side-mounted injectors at strong flashing conditions. The obtained numerical framework allows the identification of near-nozzle injection characteristics such as single plume direction, cone angle, spray initial velocity and spatial fuel density distribution. The presented results represent a unique dataset for the initialization of more-affordable Lagrangian spray models, which differentiate the behavior of side-mounted and center-mounted injectors.

Spray Photographs, Poppet Lift, and Injection Pressure of an Oscillating Poppet Injector

1987 ◽  
Vol 109 (3) ◽  
pp. 289-296 ◽  
Author(s):  
B. Chehroudi ◽  
P. Lombardi ◽  
P. G. Felton ◽  
F. V. Bracco
Keyword(s):  
Ambient Pressure ◽  
Direct Injection ◽  
Injection Pressure ◽  
Short Exposure ◽  
Chamber Pressure ◽  
Liquid Volume ◽  
Gas Temperature ◽  
Stratified Charge ◽  
Pump Speed ◽  
Injection Duration

Sprays from an injector with a conical oscillating poppet and supplied with fuel at injection rates similar to those used in direct-injection stratified-charge engines have been characterized. Instantaneous injection pressure and poppet lift were measured and short-exposure backlit photographs were taken at several times during injection. Spray axial tip penetration and velocity were determined from the photographs. The experiments were conducted in a constant-volume pressure vessel. The gas was nitrogen and the liquid was hexane. The gas temperature was either 25° or 55°C. The experiments included a systematic variation of the ambient pressure, pump speed and injected liquid volume. It was found that the structure of the spray was strongly affected by the chamber pressure. The hollow cone collapsed and injection duration, spray axial initial velocity and tip penetration decreased with increasing chamber pressure. Increasing pump speed decreased both injection duration and number of oscillations.

Influence of Spray Velocity and Structure on the Air Entrainment in the Primary Breakup Zone of High Pressure Diesel Sprays

2002 ◽  
Author(s):  
Christian Schugger ◽  
Ulrich Renz
Keyword(s):  
High Pressure ◽  
Momentum Transfer ◽  
Scattered Light ◽  
Injection Pressure ◽  
Air Entrainment ◽  
Turbulent Dispersion ◽  
Nozzle Geometry ◽  
Diesel Sprays ◽  
Spray Structure ◽  
Primary Breakup

Nozzle geometry and rail pressure influence the gas-liquid momentum transfer and the turbulent dispersion in the primary breakup zone of high-pressure Diesel sprays, and consequently the combustion processes. To investigate these phenomena, different measuring techniques have been used. The spray structure is visualized using shadowgraphy and scattered light imaging, and the axial velocities in the dense spray region have been measured using a Laser Correlation Velocimeter. Gas velocities are measured using Particle Image Velocimetry. It is found that the dimensionless velocities (related to the frictionless velocity) are independent of the injection pressure and the nozzle geometry. However the momentum transfer between the liquid phase and the surrounding air strongly depends on the spray structure. Here a sharp edged nozzle inlet promotes cavitation and turbulence levels in the nozzle which leads to stronger breakup and significantly enhanced air entrainment.

Measurement of Biodiesel Blend and Conventional Diesel Spray Structure Using X-Ray Radiography

2008 ◽  
Author(s):  
A. L. Kastengren ◽  
C. F. Powell ◽  
K.-S. Im ◽  
Y.-J. Wang ◽  
J. Wang
Keyword(s):  
Cone Angle ◽  
Injection Pressure ◽  
Fuel Distribution ◽  
X Ray ◽  
Spray Structure ◽  
Quantitative Measurements ◽  
Biodiesel Blend ◽  
Temporal And Spatial ◽  
Nozzle Geometries ◽  
Fuel Effects

The near-nozzle structure of several non-evaporating biodiesel blend sprays has been studied using x-ray radiography. Radiography allows quantitative measurements of the fuel distribution in sprays to be made with high temporal and spatial resolution. Measurements have been made at different values of injection pressure, ambient density, and with two different nozzle geometries to understand the influences of these parameters on the spray structure of the biodiesel blend. These measurements have been compared to corresponding measurements of Viscor, a diesel calibration fluid, to demonstrate the fuel effects on the spray structure. Generally, the biodiesel blend spray has a similar structure to the spray of Viscor. For the nonhydroground nozzle used in this study, the biodiesel blend spray has a slightly slower penetration into the ambient gas than the Viscor spray. The cone angle of the biodiesel blend spray is generally smaller than that of the Viscor spray, indicating that the biodiesel blend spray is denser than the Viscor spray. For the hydroground nozzle, both fuels produce sprays with initially wide cone angles that transition to narrow sprays during the steady-state portion of the injection event. These variations in cone angle with time are timed later for the biodiesel blend spray than for the Viscor spray, indicating that the dynamics of the injector needle as it opens are somewhat different for the two fuels.

X-Ray Absorption Measurements of Diesel Sprays and the Effects of Nozzle Geometry

2004 ◽  
Author(s):  
Christopher F. Powell ◽  
Stephen A. Ciatti ◽  
Seong-Kyun Cheong ◽  
Jinyuan Liu ◽  
Jin Wang
Keyword(s):  
Nozzle Geometry ◽  
Diesel Sprays ◽  
X Ray ◽  
X Ray Absorption ◽  
Absorption Measurements

scholarly journals A Staged Approach to Erosion Analysis of Wind Turbine Blade Coatings

Coatings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 681
Author(s):  
David Nash ◽  
Grant Leishman ◽  
Cameron Mackie ◽  
Kirsten Dyer ◽  
Liu Yang
Keyword(s):  
Computed Tomography ◽  
Wind Turbine ◽  
Incubation Period ◽  
Leading Edge ◽  
X Ray ◽  
Erosion Testing ◽  
Staged Approach ◽  
X Ray Computed ◽  
Droplet Impacts ◽  
Rain Erosion

The current wind turbine leading-edge erosion research focuses on the end of the incubation period and breakthrough when analysing the erosion mechanism. This work presented here shows the benefits of splitting and describing leading-edge erosion progression into discrete stages. The five identified stages are: (1) an undamaged, as-new, sample; (2) between the undamaged sample and end of incubation; (3) the end of incubation period; (4) between the end of incubation and breakthrough, and (5) breakthrough. Mass loss, microscopy and X-ray computed tomography were investigated at each of the five stages. From this analysis, it was observed that notable changes were detected at Stages 2 and 4, which are not usually considered separately. The staged approach to rain erosion testing offers a more thorough understanding of how the coating system changes and ultimately fails due to rain droplet impacts. It is observed that during microscopy and X-ray computed tomography, changes unobservable to the naked eye can be tracked using the staged approach.

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