X-Ray Radiography Measurements of Cavitating Nozzle Flow

Duke, Daniel J.; Kastengren, Alan L.; Tilocco, F. Zak; Swantek, Andrew; Powell, Christopher F.

doi:10.1615/atomizspr.2013008340

Cited by 45 publications

(46 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…provide vapour fraction data for the timeaveraged extent of cavitation in an injector-replica orifice. In-nozzle sheet cavitation has been quantified by Duke et al (2013), which, however, used an interpolation technique to compensate for the small dimensions (5×6 µm) of the monochromatic beam employed.Xray Phase Contrast Imaging (XPCI) has been, until now, primarily performed to resolve the velocity field and turbulence level of spray flows produced by real-size fuel injectors (Im et al 2013;Moon 2016).…”

Section: Introductionmentioning

confidence: 99%

High-speed visualization of vortical cavitation using synchrotron radiation

et al. 2018

View full text Add to dashboard Cite

High-speed X-ray phase-contrast imaging of the cavitating flow developing within an axisymmetric throttle orifice has been conducted using high-flux synchrotron radiation. A white X-ray beam with energy of 6 keV was utilized to visualize the highly turbulent flow at 67 890 frames per second with an exposure time of 347 ns. The working medium employed was commercial diesel fuel at flow conditions characterized by Reynolds and cavitation numbers in the range of 18 000–35 500 and 1.6–7.7, respectively. Appropriate post-processing of the obtained side-view radiographs enabled the detailed illustration of the interface topology of the arising vortical cavity. In addition, the visualization temporal and spatial resolution allowed the correlation of the prevailing flow conditions to the periodicity of cavitation onset and collapse, to the magnitude of the underlying vortical motion, as well as to the local turbulence intensity.

show abstract

Section: Introductionmentioning

confidence: 99%

High-speed visualization of vortical cavitation using synchrotron radiation

et al. 2018

View full text Add to dashboard Cite

show abstract

“…On the contrary, synchrotron X-ray sources provide a far greater degree of brilliance than laboratory-scale sources, permitting a much greater scope for advanced X-ray diagnostics. Synchrotron sources have existed for many years, but have until recently found relatively little usage by the fuel injection community (Duke et al 2013(Duke et al , 2014(Duke et al , 2015aKastengren et al 2012;Moon et al 2015;Powell et al 2000;Wang et al 2008). Nevertheless, laboratory-scale X-ray sources have improved characteristics in recent years, featuring small spot-sizes, which if coupled with developments in detector technology, provide adequate spatial resolution for multiphase flow applications.…”

Section: Introductionmentioning

confidence: 99%

“…Such problems are overcome by the use of focused synchrotron X-rays that offer an advantageous combination of temporal and spatial resolution due to high photon flux; however, the main drawback is the limitation of focus in a relatively small area (Duke et al 2013). Nevertheless, relevant studies have been performed in Battistoni et al (2015) and Duke et al (2013Duke et al ( , 2014Duke et al ( , 2015b, where multiphase flow inside a cavitating channel has been studied and compared to computational fluid dynamics (CFD) results. Researchers performed an X-ray radiography experiment on a model nozzle of 500 μm in diameter.…”

Section: Introductionmentioning

confidence: 99%

Application of X-ray micro-computed tomography on high-speed cavitating diesel fuel flows

et al. 2016

View full text Add to dashboard Cite

efficiency of such engines. Among others, the fuel injection equipment (FIE) is a key component for improving the efficiency of environmentally friendly engines. Recent advances dictate the use of extra high injection pressures, of the order of 3000 bar and tiny flow passages (injection holes) of the order of 100-250 μm in diameter, for improved fuel atomisation and combustion efficiency. Under these circumstances, cavitation has been found to develop inside fuel injection nozzles at the early studies of Badock et al. (1999), Bergwerk (1959), Chaves et al. (1995) and Nurick (1976), followed by Arcoumanis et al. (2000), Blessing et al. (2003), Mitroglou et al. (2014) and Roth et al. (2002) in more realistic real-size nozzle geometries offering optical access; equally helpful studies performed in transparent enlarged nozzle replicas [selectively (Andriotis et al. 2008;Arcoumanis et al. 2000;Miranda et al. 2003; Mitroglou and Gavaises 2013;Powell et al. 2000)] also indicate that cavitation plays an increasingly significant role in the nozzle's internal flow structure and development. Cavitation inside an injection hole is believed to enhance spray atomisation, either directly through the implosion of cavitation bubbles or indirectly because it increases turbulence in the nozzle flow (Badock et al. 1999;Walther 2002); unfortunately, under certain circumstances induces erosion (Dular and Petkovšek 2015;Koukouvinis et al. 2016) that may lead to catastrophic failures. Moreover, cavitation inside the injection holes promotes shot-toshot spray instabilities (Mitroglou et al. 2011(Mitroglou et al. , 2012Suh and Lee 2008), which, in turn, are responsible for poor combustion efficiency and increased emissions (Hayashi et al. 2013). Two distinct macroscopic forms of cavitation have been identified, which are referred to as geometryinduced and vortex or 'string' cavitation. The former can be, partially or totally, suppressed by appropriate design of the inlet hole curvature and non-cylindrical injection hole Abstract The flow inside a purpose built enlarged singleorifice nozzle replica is quantified using time-averaged X-ray micro-computed tomography (micro-CT) and highspeed shadowgraphy. Results have been obtained at Reynolds and cavitation numbers similar to those of real-size injectors. Good agreement for the cavitation extent inside the orifice is found between the micro-CT and the corresponding temporal mean 2D cavitation image, as captured by the high-speed camera. However, the internal 3D structure of the developing cavitation cloud reveals a hollow vapour cloud ring formed at the hole entrance and extending only at the lower part of the hole due to the asymmetric flow entry. Moreover, the cavitation volume fraction exhibits a significant gradient along the orifice volume. The cavitation number and the needle valve lift seem to be the most influential operating parameters, while the Reynolds number seems to have only small effect for the range of values tested. Overall, the study demonstrates that use of micro-CT can ...

show abstract

“…To quantitatively measure the local void fractions in cavitating flows, X‐ray radiography was employed in recent years . Standard X‐rays were used to examine a cavitating flow and consequently gather some quantitative information about the void fraction .…”

Section: Experimental Studiesmentioning

confidence: 99%

Cavitation in Diesel Fuel Injector Nozzles and its Influence on Atomization and Spray

2018

View full text Add to dashboard Cite

In combustors, high‐pressure fuel injector nozzles are employed for liquid atomization and spray generation. The internal flow within nozzles, especially cavitation, plays an important role in promoting the breakup of liquid jets. The formation mechanism and evolvement of cavitation are reviewed and described. Different cavitation regimes were characterized experimentally and the positive effect of cavitation on liquid atomization was confirmed. Different empirical formulas correlating the discharge coefficient with fluid‐dynamical parameters are summarized. The applicability, advantages, and disadvantages of two popular computational models for flow modeling, i.e., the interface tracking model and the homogeneous equilibrium model, are reviewed. The effects of cavitation on the generated spray are discussed.

show abstract

X-Ray Radiography Measurements of Cavitating Nozzle Flow

Cited by 45 publications

References 0 publications

High-speed visualization of vortical cavitation using synchrotron radiation

High-speed visualization of vortical cavitation using synchrotron radiation

Application of X-ray micro-computed tomography on high-speed cavitating diesel fuel flows

Cavitation in Diesel Fuel Injector Nozzles and its Influence on Atomization and Spray

Contact Info

Product

Resources

About