An experimental study of water droplets deformation and collision with airfoil

2020 ◽  
Vol 34 (14n16) ◽  
pp. 2040094
Author(s):  
Wen Li ◽  
Bo Miao ◽  
Chun-Ling Zhu ◽  
Ning Zhao
Keyword(s):  
Experimental Study ◽  
Weber Number ◽  
High Speed ◽  
Leading Edge ◽  
Deformation Mode ◽  
Water Droplets ◽  
Droplet Deformation ◽  
Naca0012 Airfoil ◽  
Droplet Movement ◽  
Pass Through

When aircraft pass through the clouds that contain super cooled water droplets during aviation, the droplets collide with the wing surface and ice is formed, which induces a significant threat to aviation safety. Studies on droplet movement in gaseous medium are prerequisite for deicing/anti-icing researches. So, in this work, an experimental study is performed on water droplet deformation as the droplets approach the leading edge of an airfoil. This experiment is carried out in a vertical wind tunnel, with a NACA0012 airfoil model assembled 4.3 m downstream of the droplet generator. The influence of Weber number (ranging from 0.2 to 36) on the deformation of a 2 mm diameter droplet is thoroughly investigated. The results indicate that droplets maintain initial form with Weber number under 10; after that droplet deforms into remarkable bag deformation as Weber number reaches to 19, and bag-stamen deformation mode as Weber number is above 20. This observed correlation between Weber number and deformation mode is validated through comparing with published simulation results. Furthermore, using the high-speed camera, clear images of the droplet structure during the deformation process are taken and are shown in detail in this work.

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

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
S. Sor ◽  
A. García-Magariño ◽  
A. Velazquez
Keyword(s):  
Experimental Study ◽  
Imaging System ◽  
Leading Edge ◽  
Base Flow ◽  
Particle Image Velocimetry System ◽  
Edge Region ◽  
Droplet Deformation ◽  
Droplet Behavior ◽  
Shoulder Region ◽  
Set Up

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.

Direct numerical simulation of the droplet deformation in the external flow at various Reynolds and Weber numbers

2020 ◽  
Author(s):  
Anna Zotova ◽  
Yuliya Troitskaya ◽  
Daniil Sergeev ◽  
Alexander Kandaurov
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Reynolds Number ◽  
Direct Numerical Simulation ◽  
Software Package ◽  
Weber Number ◽  
Deformation Mode ◽  
Stationary Flow ◽  
External Flow ◽  
Droplet Deformation

<p>A lot of experimental works is devoted to studying behaviour of a droplet in the flow of the external medium. It is shown in [1] that mode of the deformation of droplet in the stationary flow is affected by the Weber number and the Reynolds number. The authors distinguish two types of the droplet deformation in the external flow: the dome-shaped deformation and the bowl-shaped one.</p><p>Using the Basilisk software package, direct numerical simulation of the process of deformation of liquid drop in the gas stream was carried out. We examined the problem of the following geometry: a drop of liquid with diameter of 5 mm was placed in the gas stream at the speed of 30 m/s. The density of liquid and gas correspond to the density of water and air, the viscosity of liquid is equal to the viscosity of water. The viscosity of gas and the surface tension at the interface between liquid and gas are determined by the set values of the Reynolds (50 - 3000) and the Weber (2 - 30) numbers. Two main modes of the drop deformation were observed: the dome-shaped deformation and the bowl-shaped one, there is a transitional deformation mode between them. The map of deformation modes is constructed for comparison with the experimental data available in the literature. It was found that the dependence of the Weber number corresponding to the transition from one deformation mode to another on the Reynolds number is well described by the power law proposed in the literature.</p><p> </p><p>This work was supported by the RFBR projects 19-05-00249, 18-35-20068, 18-55-50005, 18-05-60299, 20-05-00322 (familiarization with the Basilisk software package) and the Grant of the President No. MK-3184.2019.5, work on comparison with experimental data was supported by the RSF project No. 18-77-00074, carrying out numerical experiment was supported by the RSF project No. 19-17-00209, A.N. Zotova is additionally supported by the Ministry of Education and Science of the Russian Federation (Government Task No. 0030-2019-0020). The authors are grateful to the FCEIA employee: UNR - CONICET (Rosario, Rep. Argentina) Dr. Ing. César Pairetti.</p><p>[1] Hsiang, L.-P., Faeth, G. M., Int. J. Multiphase Flow 21(4), 545-560 (1995).</p>

Experimental study of heat transfer in the boundary layer of a flat plate with the impact of weak shock waves on the leading edge

2020 ◽  
Author(s):  
V. L. Kocharin ◽  
A. A. Yatskikh ◽  
D. S. Prishchepova ◽  
A. V. Panina ◽  
Yu. G. Yermolaev ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Experimental Study ◽  
Shock Waves ◽  
Flat Plate ◽  
Leading Edge ◽  
Weak Shock ◽  
The Impact

Experimental study on laminated glass responses of high-speed trains subject to windblown sand particles loading

2021 ◽  
Vol 300 ◽  
pp. 124332
Author(s):  
Gongxun Deng ◽  
Wen Ma ◽  
Yong Peng ◽  
Shiming Wang ◽  
Song Yao ◽  
...  
Keyword(s):  
Experimental Study ◽  
High Speed ◽  
Laminated Glass ◽  
Windblown Sand ◽  
High Speed Trains ◽  
Sand Particles

scholarly journals Study on the Effect of Nanoparticle Used in Nano-Fluid Flooding on Droplet–Interface Electro-Coalescence

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1764
Author(s):  
Donghai Yang ◽  
Huayao Sun ◽  
Qing Chang ◽  
Yongxiang Sun ◽  
Limin He
Keyword(s):  
Interfacial Tension ◽  
Oil Recovery ◽  
Liquid Bridge ◽  
High Speed ◽  
Droplet Formation ◽  
Force Balance ◽  
Secondary Droplet ◽  
Droplet Deformation ◽  
Deformation Degree ◽  
Nano Fluid

Nano-fluid flooding is a new method capable of improving oil recovery; however, nanoparticles (NPs) significantly affect electric dehydration, which has rarely been investigated. The effect of silica (SiO2) NPs on the droplet–interface coalescence was investigated using a high-speed digital camera under an electric field. The droplet experienced a fall, coalescence, and secondary droplet formation. The results revealed that the oil–water interfacial tension and water conductivity changed because of the SiO2 NPs. The decrease of interfacial tension facilitated droplet deformation during the falling process. However, with the increase of particle concentration, the formed particle film inhibited the droplet deformation degree. Droplet and interface are connected by a liquid bridge during coalescence, and the NP concentration also resulted in the shape of this liquid bridge changing. The increase of NP concentration inhibited the horizontal contraction of the liquid bridge while promoting vertical collapse. As a result, it did not facilitate secondary droplet formation. Moreover, the droplet falling velocity decreased, while the rising velocity of the secondary droplet increased. Additionally, the inverse calculation of the force balance equation showed that the charge of the secondary droplet also increased. This is attributed to nanoparticle accumulation, which resulted in charge accumulation on the top of the droplet.

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