Proyecto de Investigación: DEFORMACIÓN Y ROTURA DE GOTAS CON Y SIN SOBRE-ENFRIAMIENTO EN FLUJOS DE INTERÉS AERONÁUTICO
Cargando...
Colaboradores
Financiadores
ID
DPI2016-75296-P
Autores
Publicaciones
Droplet ratio deformation model in combination with droplet breakup onset modeling
(Aerospace Research Central, 2020-08-25) García Magariño, A.; Velázquez, Ángel; Sor, Suthyvann; Instituto Nacional de Técnica Aeroespacial (INTA); Ministerio de Economía y Competitividad (MINECO)
Droplet deformation and breakup in the continuously accelerated flowfield generated by an incoming airfoil have been studied. The upper limit of droplet deformation and the minimum distance to the airfoil model at which the breakup onset takes place have been modeled. Three analytical equations have been developed based on the combination of two models: a droplet deformation and trajectory model for droplets in a continuously accelerated flowfield, and a breakup model for droplets in the vicinity of a leading edge of an airfoil model. The verification was made using experimental data obtained for water droplets whose diameters were in the range from 400 to 1800 μm impinging on airfoils of three different chord sizes moving at velocities from 50 to 90 m/s90 m/s. The rotating arm facility at National Institute of Aerospace Technology was used for this purpose. The analytical equations of the model were in good agreement with the experimental data. The upper limit of droplet deformation was verified by 95.40% of the tested experimental cases, and the minimum distance to the airfoil was verified in 99.65% of the cases.
Breakup criterion for droplets exposed to the unsteady flow generated by an incoming aerodynamic surface
(Elsevier, 2020-03-15) López Gavilan, Pablo; Velázquez, Ángel; García Magariño, A.; Sor, Suthyvann; Instituto Nacional de Técnica Aeroespacial (INTA); Ministerio de Economía y Competitividad (MINECO)
An experimental and theoretical study is presented on the problem of droplet breakup exposed to a continuously accelerating flow generated by an incoming aerodynamics surface. Droplet breakup experiments were carried out in a rotating arm facility. Droplet diameters were of the order of 1 mm. The maximum velocity of the airfoils located at the end of the rotating arm was 90 m/s. Droplet deformation was computed using a phenomenological model developed previously by the authors. The dynamics of this deformation was coupled to an instability model based on the growth of Rayleigh-Taylor waves at the droplet surface. It was found that, within the experimental uncertainty, breakup occurs when the instability wavelength approaches the droplet hydraulic diameter assuming that it flattens and deforms as an oblate spheroid. This fact allowed for the generation of a theoretical closed-form droplet deformation and breakup model that predicts the onset of breakup with discrepancies of about ±10 % when compared to the experimental results. Finally, as an application case, this closed-form model is used to simulate an actual situation in which the objective is to investigate whether a series of droplets that are approached by an airfoil either impact on its surface, or break prior to collision, or break without colliding, or pass through undamaged.
Droplet deformation and trajectory without interferences in the incoming airfoil shoulder region
(Aerospace Research Central, 2020-05-22) García Magariño, A.; Sor, Suthyvann; Velázquez, Ángel; Instituto Nacional de Técnica Aeroespacial (INTA); Ministerio de Economía y Competitividad (MINECO)
A new experimental campaign has been conducted in the shoulder region of an incoming airfoil of chord 1050 mm, where droplets are separated enough to neglect interferences between them. Droplets of three sizes (500, 950, and 1250 μmof radius) were allowed to fall in the path of an incoming airfoil while shadowgraph images were recorded by a high-speed video camera at 40,000 fps. The airfoil model was placed at the end of a rotating arm and moved at four velocities (30, 40, 50, and 60 m∕s). Three different regions of the shoulder were tested. Droplet deformation and trajectories are presented. Droplets evolve as a conjunction of two half-oblate spheroids that tilt as the model approaches. The tilting is larger in the higher regions of the shoulder. The trajectory model derived for droplet in the stagnation line of a moving airfoil has been formally derived for the shoulder region and applied to the experimental data, showing very good agreement being the mean discrepancy less than 4% for the trajectory and 10% for the deformation.
Droplet breakup criterion in airfoils leading edge vicinity
(Aerospace Research Central, 2018-05-07) García Magariño, A.; Velázquez, Ángel; Sor, Suthyvann; Instituto Nacional de Técnica Aeroespacial (INTA); Ministerio de Economía y Competitividad (MINECO)
A new breakup criterion is proposed in this paper for droplets subject to the flowfield generated by an incoming airfoil (that is, the criterion should be applied only to this type of aerodynamics flow). This criterion is based on the study of the characteristic times involved in the problem. These are the characteristic external flowfield variation time and the characteristic droplet deformation time. The criterion takes the shape of an empirical correlation that relates the Weber number at the onset of the breakup to the external flowfield and droplet characteristics. Experimental data on the droplet deformation and breakup tests conducted in a rotating arm facility are used to generate the data used to develop the correlation. Droplets, with diameters in the range of 0.3–3.6 mm, are allowed to fall in the path of an incoming airfoil attached to the end of a rotating arm. Airfoil velocities vary between 50 and 90 m∕s. The airfoil leading-edge radius varies from 0.030 to 0.103 m. Experiments are recorded with a high-speed camera using the shadowgraph illumination technique. The empirical breakup correlation applies to droplets that break in the bag and stamen mode. Some additional limited data on droplets that break in the bag and the shear mode are analyzed to see how they fit into the correlation.
