Liquid jet core characterization in a model crossflow airblast atomizer

Patil, Shirin; Sahu, Srikrishna

doi:10.1016/j.ijmultiphaseflow.2021.103688

Cited by 8 publications

(2 citation statements)

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“…However, if the experiment and the simulation have the same setup, the results provided by this technique can be used to validate the results obtained using numerical simulations. Optical Connectivity has been applied in different experiments, primarily to coaxial airblast atomizers [77,78], but also to automotive injectors [79]. Figure 1.18 depicts the comparison between Shadowgraphy and Optical Connectivity of a coaxial airblast atomizer from [78].…”

Section: Optical Connectivitymentioning

confidence: 99%

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Computational and Experimental Study of the Primary Atomisation Process under Different Injection Conditions

Montero¹

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The primary atomisation process is the mechanism by which a liquid vein breaks into droplets in a gaseous ambient. This process is present in many engineering applications accomplishing different tasks. Sometimes it is a previous step before being burned, as in the energy or propulsion industry, where the objective is to extract the specific energy of the liquid. In other sectors, such as the coating or fire extinction, the objective is to maximise the area covered by the droplet cloud. However, although atomisation is a fundamental part of several industrial processes, it is far from fully understood. The atomisation process is a mixture of gas-liquid interaction phenomena within a turbulent field that takes place in the near-field, which is the denser region of the spray.When trying to shed light on the primary atomisation process, the main issue is the lack of definitive physical theories able to link the complex breakup events and the turbulence. The principal impediment that prevents the investigation from breaking through the atomisation process is the inability of the classic optical techniques to provide information from the dense region of the spray. Only in the last years, newer techniques based on X-Ray could provide new information on spray characteristics near the nozzle outlet. This also affects the computational primary atomisation models that, as there is no available experimental information on the dense region, require an accurate calibration of their constants to provide reliable results on the far-field. This thesis focuses on improving the knowledge of the primary atomisation process, especially on how the injection conditions affect the spray development in the near field from two different standpoints. On the one hand, with a computational approach using Direct Numerical Simulations and on the other hand, experimentally using Near-Field Microscopy.The computational study is focused on varying the inflow Reynolds and Weber numbers. Results show that increasing the Reynolds number improves the liquid disintegration, exhibiting an increase of generated droplets and a finer droplet cloud. However, the lack of a fully developed inflow turbulent profile leads to characteristic behaviours on the breakup length of the spray that also increases with the Reynolds number. The number of droplets increases when the Weber number increases, but the characteristic droplet sizes remain the same. The breakup length does not vary, suggesting that the surface tension variations affect the droplet and ligament breakup but not the core disintegration itself. With the results obtained from both studies, a phenomenological model is proposed to predict the droplet size distribution depending on the injection conditions.Additionally, using elliptical nozzles, the number of detected droplets increases compared with the round spray and maintain similar spray apertures. However, when using extremely eccentric nozzles, the inflow turbulence decrease counteracts the elliptical sprays' benefits.Regarding the experimental ...

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Section: Optical Connectivitymentioning

confidence: 99%

“…Optical Connectivity has been applied in different experiments, primarily to coaxial airblast atomizers [77,78], but also to automotive injectors [79]. Figure 1.18 depicts the comparison between Shadowgraphy and Optical Connectivity of a coaxial airblast atomizer from [78].…”

Section: Optical Connectivitymentioning

confidence: 99%