End-of-Injection Behavior of Diesel Sprays Measured With X-Ray Radiography

2012 ◽  
Vol 134 (9) ◽  
Author(s):  
Alan Kastengren ◽  
Christopher F. Powell ◽  
F. Zak Tilocco ◽  
Zunping Liu ◽  
Seoksu Moon ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Diesel Sprays ◽  
Engine Emissions ◽  
X Ray ◽  
Fuel Flow ◽  
Spray Density ◽  
Spray Plume ◽  
Unburned Fuel ◽  
Spray Velocity ◽  
Dilute Mixture

The behavior of diesel fuel sprays at the end of injection is poorly understood, yet has important implications regarding diesel engine emissions. Recent research has shown that at the end of injection, an entrainment wave is created, causing the fuel spray to rapidly entrain ambient gas. This rapid entrainment creates a dilute mixture of fuel that may be a source of unburned fuel emissions. In this study, X-ray radiography is used to quantitatively probe the fuel mass distribution in diesel sprays at the end of injection. Analysis of the spray velocity at steady-state suggests an entrainment wave speed of several hundred m/s, which is supported by the appearance of a traveling entrainment wave at low ambient density. The spray density declines most rapidly near the nozzle, a behavior that matches the expected entrainment wave behavior. The dilution of the spray plume is most prominent in the central dense region of the spray. Three-dimensional reconstructions of the spray density at the end of injection show that the spray plume considerably widens, enhancing the dilution caused by the reduction in fuel flow.

End-of-Injection Behavior of Diesel Sprays Measured With X-Ray Radiography

2010 ◽  
Author(s):  
Alan Kastengren ◽  
Christopher F. Powell ◽  
Zunping Liu ◽  
Seoksu Moon ◽  
Jian Gao ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Contrast Imaging ◽  
Diesel Sprays ◽  
Engine Emissions ◽  
X Ray ◽  
Spray Density ◽  
Spray Plume ◽  
Spray Distribution ◽  
Unburned Fuel ◽  
Spray Velocity

The behavior of diesel fuel sprays at the end of injection is poorly understood, yet has important implications regarding diesel engine emissions. Recent research has shown that at the end of injection, an entrainment wave is created, causing the fuel spray to rapidly entrain ambient gas. This rapid entrainment creates a dilute mixture of fuel that may be a source of unburned fuel emissions. In this study, x-ray radiography is used to examine the end-of-injection behavior of diesel sprays. X-ray radiography permits quantitative mass distribution measurements in dense sprays, providing data that cannot be obtained with optical techniques. Analysis of the spray velocity at steady-state suggests an entrainment wave speed of several hundred m/s, which is supported by the appearance of a travelling entrainment wave at low ambient density. The spray density declines most rapidly near the nozzle, behavior that matches the expected entrainment wave behavior. In several cases, the spray distribution in a cross-section across the nozzle axis becomes smoother at the end of injection. Three-dimensional reconstructions of the spray density at the end of injection show that the spray plume widens considerably, enhancing the dilution caused by the reduction in spray mass in the flowfield. Measurements of injector needle motion with x-ray phase contrast imaging show that throttling across the needle seat may cause a smearing of the ideally sharp entrainment wave.

The Effects of Diesel Injector Needle Motion on Spray Structure

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
C. F. Powell ◽  
A. L. Kastengren ◽  
Z. Liu ◽  
K. Fezzaa
Keyword(s):  
Three Dimensional ◽  
Cfd Modeling ◽  
Needle Valve ◽  
Time Resolved ◽  
Fuel Injectors ◽  
Fuel Distribution ◽  
X Ray ◽  
Fuel Flow ◽  
Dependent Flow ◽  
Time Resolved Imaging

The internal structure of diesel fuel injectors is known to have a significant impact on the steady-state fuel distribution within the spray. However, little experimental or computational work has been performed on the dynamics of fuel injectors. Recent studies have shown that it is possible to measure the three-dimensional geometry of the injector nozzle, and to track changes in that geometry as the needle opens and closes in real time. This has enabled the dynamics of the injector to be compared with the dynamics of the spray, and allows computational fluid dynamics (CFD) simulations to use realistic time-dependent flow passage geometries. In this study, X-ray phase-enhanced imaging has been used to perform time-resolved imaging of the needle seat area in several common-rail diesel injection nozzles. The fuel distributions of the sprays emitted by these injectors were also studied with fast X-ray radiography. Correlations between eccentric motions of the injector needle valve and oscillations in the fuel density as it emerges from the nozzle are examined. CFD modeling is used to interpret the effect of needle motion on fuel flow.

The Effects of Diesel Injector Needle Motion on Spray Structure

2009 ◽  
Author(s):  
C. F. Powell ◽  
A. L. Kastengren ◽  
Z. Liu ◽  
K. Fezzaa
Keyword(s):  
Three Dimensional ◽  
Cfd Modeling ◽  
Needle Valve ◽  
Time Resolved ◽  
Fuel Injectors ◽  
Fuel Distribution ◽  
X Ray ◽  
Fuel Flow ◽  
Dependent Flow ◽  
Time Resolved Imaging

The internal structure of diesel fuel injectors is known to have a significant impact on the steady-state fuel distribution within the spray. However, little experimental or computational work has been performed on the dynamics of fuel injectors. Recent studies have shown that it is possible to measure the three-dimensional geometry of the injector nozzle, and to track changes in that geometry as the needle opens and closes in real time. This has enabled the dynamics of the injector to be compared with the dynamics of the spray, and allows CFD simulations to use realistic time-dependent flow passage geometries. In this study, x-ray phase-enhanced imaging has been used to perform time-resolved imaging of the needle seat area in several common-rail diesel injection nozzles. The fuel distributions of the sprays emitted by these injectors were also studied with fast x-ray radiography. Correlations between eccentric motions of the injector needle valve and oscillations in the fuel density as it emerges from the nozzle are examined. CFD modeling is used to interpret the effect of needle motion on fuel flow.

Ribosome Structural Organization

1974 ◽  
Vol 32 ◽  
pp. 332-333
Author(s):  
James A. Lake
Keyword(s):  
Ribosomal Proteins ◽  
Structural Organization ◽  
Three Dimensional ◽  
Small Subunit ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
Specific Antibodies ◽  
X Ray ◽  
E Coli ◽  
Complete Sequences

The understanding of ribosome structure has advanced considerably in the last several years. Biochemists have characterized the constituent proteins and rRNA's of ribosomes. Complete sequences have been determined for some ribosomal proteins and specific antibodies have been prepared against all E. coli small subunit proteins. In addition, a number of naturally occuring systems of three dimensional ribosome crystals which are suitable for structural studies have been observed in eukaryotes. Although the crystals are, in general, too small for X-ray diffraction, their size is ideal for electron microscopy.

3-D reconstruction of molecular shape from microcrystal thin sections

1983 ◽  
Vol 41 ◽  
pp. 748-749
Author(s):  
S. Cusack ◽  
J.-C. Jésior
Keyword(s):  
Three Dimensional ◽  
Molecular Shape ◽  
Biological Molecules ◽  
Fourier Space ◽  
Single Particles ◽  
Thin Sections ◽  
Standard Methods ◽  
X Ray ◽  
X Ray Crystallography ◽  
Dimensional Reconstruction

Three-dimensional reconstruction techniques using electron microscopy have been principally developed for application to 2-D arrays (i.e. monolayers) of biological molecules and symmetrical single particles (e.g. helical viruses). However many biological molecules that crystallise form multilayered microcrystals which are unsuitable for study by either the standard methods of 3-D reconstruction or, because of their size, by X-ray crystallography. The grid sectioning technique enables a number of different projections of such microcrystals to be obtained in well defined directions (e.g. parallel to crystal axes) and poses the problem of how best these projections can be used to reconstruct the packing and shape of the molecules forming the microcrystal.Given sufficient projections there may be enough information to do a crystallographic reconstruction in Fourier space. We however have considered the situation where only a limited number of projections are available, as for example in the case of catalase platelets where three orthogonal and two diagonal projections have been obtained (Fig. 1).

X-ray microtomography

1988 ◽  
Vol 46 ◽  
pp. 998-999
Author(s):  
H.W. Deckman ◽  
B.F. Flannery ◽  
J.H. Dunsmuir ◽  
K.D' Amico
Keyword(s):  
Computed Tomography ◽  
Internal Structure ◽  
Imaging Technique ◽  
Three Dimensional ◽  
Tissue Structure ◽  
Individual Element ◽  
X Ray ◽  
Non Invasive ◽  
Panoramic Imaging ◽  
Three Dimensional Images

We have developed a new X-ray microscope which produces complete three dimensional images of samples. The microscope operates by performing X-ray tomography with unprecedented resolution. Tomography is a non-invasive imaging technique that creates maps of the internal structure of samples from measurement of the attenuation of penetrating radiation. As conventionally practiced in medical Computed Tomography (CT), radiologists produce maps of bone and tissue structure in several planar sections that reveal features with 1mm resolution and 1% contrast. Microtomography extends the capability of CT in several ways. First, the resolution which approaches one micron, is one thousand times higher than that of the medical CT. Second, our approach acquires and analyses the data in a panoramic imaging format that directly produces three-dimensional maps in a series of contiguous stacked planes. Typical maps available today consist of three hundred planar sections each containing 512x512 pixels. Finally, and perhaps of most import scientifically, microtomography using a synchrotron X-ray source, allows us to generate maps of individual element.

Revealing gross three-dimensional structure in the SEM

1987 ◽  
Vol 45 ◽  
pp. 656-657
Author(s):  
Sterling P. Newberry
Keyword(s):  
Freeze Drying ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Small Object ◽  
Final Solution ◽  
Dimensional Representation ◽  
X Ray ◽  
Three Dimensional Representation ◽  
Freeze Dried ◽  
Critical Point Drying

The beautiful three dimensional representation of small object surfaces by the SEM leads one to search for ways to open up the sample and look inside. Could this be the answer to a better microscopy for gross biological 3-D structure? We know from X-Ray microscope images that Freeze Drying and Critical Point Drying give promise of adequately preserving gross structure. Can we slice such preparations open for SEM inspection? In general these preparations crush more readily than they slice. Russell and Dagihlian got around the problem by “deembedding” a section before imaging. This some what defeats the advantages of direct dry preparation, thus we are reluctant to accept it as the final solution to our problem. Alternatively, consider fig 1 wherein a freeze dried onion root has a window cut in its surface by a micromanipulator during observation in the SEM.

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