Experimental characterization of water droplet deformation and breakup in the vicinity of a moving airfoil

García-Magariño, Adelaida; Sor, Suthyvann; Velázquez, A.

doi:10.1016/j.ast.2015.06.025

Cited by 25 publications

(9 citation statements)

References 29 publications

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“…The flow field generated by the airfoil was characterized in advance using the Particle Image Velocimeter (PIV) technique. A complete description of this characterization can be found in [17]. This characterization allows us to correlate the conditions at which each breakup stage take place.…”

Section: Methodsmentioning

confidence: 99%

“…The rotating arm facility had already been used to study water droplet deformation and breakup in a continuously accelerated flow field using the shadowgraph technique [17]. A photograph of the experimental setup can be observed in Figure 1.…”

Section: Methodsmentioning

confidence: 99%

“…Due to the difficulty associated to using direct illumination in transparent liquids, the shadowgraph technique has mainly been used in the past, providing only the distorted droplet contour. Previous studies by the authors were based on data obtained by shadowgraph illumination technique [17]. However, direct illumination allows for obtaining more information of the structure, which can provide a better understanding of the details of the process.…”

Section: Introductionmentioning

confidence: 99%

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Visualization of water droplet deformation and breakup in a continuously accelerating flow field

García-Magariño

Sor

Velázquez

2017

Proceedings ILASS–Europe 2017. 28th Conference on Liquid Atomization and Spray Systems

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A new specific direct illumination technique is proposed for studying the deformation and breakup process of droplets that are exposed to a continuously increasing flow field. This type of flow field is in contrast to the traditional shock-tube experiments where droplets are suddenly exposed to a constant high airstream. In order to generate a continuously accelerated flow field the rotating arm facility at INTA is used. Droplets are allowed to fall in the path of an incoming airfoil mounted at the end of a rotating arm. Under certain conditions, these droplet deform and breakup before impinging on the airfoil. The incoming airfoil is a key element in the illumination technique. Droplets of 0.8 mm of diameter immersed in the flow field generated by an airfoil model of chord 0.690m approaching at 80 m/s were chosen for this study and were found to undergo a breakup process similar to the bag and stamen breakup found in the literature. Each of the stages at this type of breakup process was investigated by means of this new direct illumination technique and a high resolution camera. These images were compared to those images obtained using shadowgraph illumination technique and a high speed camera under the same conditions. Five different stages were studied and characterized. The final objective in this study was to visualize and identify fluid structures that occur during the deformation and breakup process in a continuously accelerated flow field in order to develop and fine tune physical-mathematical models. KeywordsDroplet Breakup, Visualization, Accelerating Flow. IntroductionDroplet aerobreakup has been studied mainly in shock tube [1,2] or wind tunnels facilities [3,4,5], where the droplet suddenly experiences a high constant air speed. Two comprehensive reviews on this field are those of Guildenbecher et al. [6] and Theofanous [7]. In the first one, attention was paid to the breakup morphology and a similar classification of breakup mode as the one found in Pilch and Erdman [8] was established: Vibrational breakup, Bag Breakup, Multimode (Bag and Stamen), Sheet Stripping (Sheet Thinning), and Catastrophic Breakup. The second review made a good discussion on the two main mechanisms leading to breakup: RayleighTaylor piercing and shear-induced entrainment. However, these two reviews [6,7] cover data obtained in facilities where droplets are suddenly exposed to a high constant velocity air stream. This is in contrast with the problem studied in this paper, where droplet are initially in a quiescent flow and then the air velocity starts to increase gradually with an acceleration that also increases, until the acceleration and the velocity reach values that allow for droplet breakup. The problem is a non-stationary problem and transient effects need to be considered. Accelerating and decelerated non-uniform flow fields have only been studied for non-deformable spheres [9,10], or droplets that are small enough to neglect deformation [11] and it has proved to be a very complex problem since there still ex...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Visualization of water droplet deformation and breakup in a continuously accelerating flow field

García-Magariño

Sor

Velázquez

2017

Proceedings ILASS–Europe 2017. 28th Conference on Liquid Atomization and Spray Systems

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“…In a previous study, the authors of this article, García-Magariño et al [20], carried out an experimental study on single-droplet deformation in the leading edge region (close to the stagnation streamline) of an airfoil. Details of the experimental setup as well as the data reduction techniques that were used are given in [21].…”

Section: Introductionmentioning

confidence: 99%

Rotating Arm-Based Experimental Study on Droplet Behavior in the Shoulder Region of an Aircraft Aerodynamic Surface

Sor

García-Magariño

Velázquez

2017

International Journal of Aerospace Engineering

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An experimental study has been performed on water droplet deformation in the shoulder region of an airfoil. The experiments have been carried out in a rotating arm facility 2.2 m long and able to rotate up to 400 rpm (90 m/s). A blunt airfoil model (chord length equal to 0.468 m) was placed at the end of the arm. A droplet generator was used to generate a stream of water droplets with an initial diameter of 1000 μm. An imaging system was set up to record the trajectories and deformations of the droplets in three different regions close to the airfoil shoulder. The base flow field was characterized using a particle image velocimetry system. The experiments show that droplet deformation results in the shoulder region of the airfoil are different from those pertaining to the leading edge region. In particular, droplets in the shoulder region tend to rotate to the direction of the incoming airfoil which generates an interference effect between the droplets that make up the stream. These differences have been quantified applying an existing theoretical model specifically developed for the leading edge region to the results obtained in the present study.

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“…The work presented in this chapter has been submitted, accepted and published in Aerospace Science and Technology [25] during the last year.…”

Section: Chapter 3 Experimental Testingmentioning

confidence: 99%

Water droplet deformation and breakup in the vicinity of the leading edge of an incoming airfoil

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Experimental characterization of water droplet deformation and breakup in the vicinity of a moving airfoil

Cited by 25 publications

References 29 publications

Visualization of water droplet deformation and breakup in a continuously accelerating flow field

Visualization of water droplet deformation and breakup in a continuously accelerating flow field

Rotating Arm-Based Experimental Study on Droplet Behavior in the Shoulder Region of an Aircraft Aerodynamic Surface

Water droplet deformation and breakup in the vicinity of the leading edge of an incoming airfoil

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