Study of the Effect of Surface Roughness on Droplet Spreading Behavior Using CFD Modeling

2014 ◽  
Vol 625 ◽  
pp. 378-381
Author(s):  
Mohd Syaifullah Bin Ramli ◽  
Abdul Basit ◽  
Ku Zilati Ku Shaari ◽  
Lau Kok Keong
Keyword(s):  
Impact Velocity ◽  
Smooth Surface ◽  
Curve Surface ◽  
High Impact ◽  
Cfd Modeling ◽  
Spreading Factor ◽  
Droplet Spreading ◽  
Spreading Behavior ◽  
High Impact Velocity ◽  
Effect Of Surface

Water droplet spreading has been simulated at impact velocity of 3.0 m/s, 1.5 m/s and 0.5 m/s on surfaces with texture of ‘triangle’, ‘square’, ‘curve’ as well as smooth surface of aluminum. Higher impact velocity induced the droplet to spread faster and has a bigger diameter. At high impact velocity, spreading factor cannot be determined due to splashing and droplet break ups. In addition, at 1.5 m/s the phenomenon of splashing was found to be almost absent except on the surface with ‘square’ texture. ‘Square’ surface tends to splash earlier compared to other surfaces and is followed by ‘triangle’, ‘curve’ and smooth surface. At low impact velocity, the smooth surface has the highest spreading factor and followed by ‘triangle’, ‘square’ and ‘curve’ surface.

scholarly journals Drone Launched Short Range Rockets

Aerospace ◽  
2020 ◽  
Vol 7 (6) ◽  
pp. 76
Author(s):  
Mikhail V. Shubov
Keyword(s):  
High Altitude ◽  
Impact Velocity ◽  
Initial Velocity ◽  
Short Range ◽  
Thermal Protection ◽  
High Impact ◽  
High Impact Velocity

A concept of drone launched short range rockets (DLSRR) is presented. A drone or an aircraft rises DLSRR to a release altitude of up to 20 km. At the release altitude, the drone or an aircraft is moving at a velocity of up to 700 m/s and a steep angle of up to 68° to the horizontal. After DLSRRs are released, their motors start firing. DLSRRs use slow burning motors to gain altitude and velocity. At the apogee of their flight, DLSRRs release projectiles which fly to the target and strike it at high impact velocity. The projectiles reach a target at ranges of up to 442 km and impact velocities up to 1.88 km/s. We show that a rocket launched at high altitude and high initial velocity does not need expensive thermal protection to survive ascent. Delivery of munitions to target by DLSRRs should be much less expensive than delivery by a conventional rocket. Even though delivery of munitions by bomber aircraft is even less expensive, a bomber needs to fly close to the target, while a DLSRR carrier releases the rockets from a distance of at least 200 km from the target. All parameters of DLSRRs, and their trajectories are calculated based on theoretical (mechanical and thermodynamical) analysis and on several MatLab programs.

High impact velocity on multi-layered composite of polyether ether ketone and aluminium

2015 ◽  
Vol 22 (8) ◽  
pp. 705-715 ◽  
Author(s):  
D. García-González ◽  
M. Rodríguez-Millán ◽  
A. Vaz-Romero ◽  
A. Arias
Keyword(s):  
Impact Velocity ◽  
Layered Composite ◽  
High Impact ◽  
Polyether Ether Ketone ◽  
High Impact Velocity ◽  
Ether Ketone

scholarly journals Axial Force Coefficient of APFSDS Projectile

2020 ◽  
Vol 1 ◽  
pp. 1-15
Author(s):  
Ammar Trakic
Keyword(s):  
Kinetic Energy ◽  
Impact Velocity ◽  
Axial Force ◽  
High Impact ◽  
Cfd Model ◽  
Force Coefficient ◽  
Terminal Ballistics ◽  
High Impact Velocity ◽  
The World ◽  
The Impact

Armor-piercing ammunition is primarily used to combat against heavy armored targets (tanks), but targets can be light armored vehicles, aircraft, warehouse, structures, etc. It has been shown that the most effective type of anti-tank ammunition in the world is the APFSDS ammunition (Armor Piercing Fin Stabilized Discarding Sabot). The APFSDS projectile flies to the target and with his kinetic energy acts on the target, that is, penetrates through armor and disables the tank and his crew. Since the projectile destroys target with his kinetic energy, then it is necessary for the projectile to have the high impact velocity. The decrease in the velocity of a projectile, during flight, is mainly influenced by aerodynamic forces. The most dominant is the axial force due to the laid trajectory of the projectile. By knowing the axial force (axial force coefficient), it is possible to predict the impact velocity of the projectile, by external ballistic calculation, in function of the distance of the target, and to define the maximum effective range from the aspect of terminal ballistics. In this paper two models will be presented for predicting axial force (the axial force coefficient) of an APFSDS projectile after discarding sabot. The first model is defined in STANAG 4655 Ed.1. This model is used to predict the axial force coefficient for all types of conventional projectiles. The second model for predicting the axial force coefficient of an APFSDS projectile, which is presented in the paper, is the CFD-model (Computed Fluid Dynamics).

Effect of Timing and Velocity of Impact on Ventricular Myocardial Rupture

1983 ◽  
Vol 105 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Ian V. Lau
Keyword(s):  
Impact Velocity ◽  
High Speed ◽  
Left Ventricular ◽  
High Impact ◽  
Muscle Stiffness ◽  
Cardiac Rupture ◽  
Myocardial Wall ◽  
High Impact Velocity ◽  
Myocardial Rupture ◽  
The Impact

The effects of impact timing during the cardiac cycle on the sensitivity of the heart to impact-induced rupture was investigated in an open-chest animal model. Direct mechanical impacts were applied to two adjacent sites on the exposed left ventricular surface at the end of systole or diastole. Impacts at 5 m/s and a contact stroke of 5 cm at the end of systole resulted in no cardiac rupture in seven animals, whereas similar impacts at the end of diastole resulted in six cardiac ruptures. Direct impact at 15 m/s and a contact stroke of 2 cm at the end of either systole or diastole resulted in perforationlike cardiac rupture in all attempts. At low-impact velocity the heart was observed in high-speed movie to bounce away from the impact interface during a systolic impact, but deform around the impactor during a diastolic impact. The heart generally remained motionless during the downward impact stroke at high-impact velocity in either a systolic or diastolic impact. The lower ventricular pressure, reduced muscle stiffness, thinner myocardial wall and larger mass of the filled ventricle probably contributed to a greater sensitivity of the heart to rupture in diastole at low-impact velocity. However, the same factors had no role at high-impact velocity.

scholarly journals Universal rescaling of drop impact on smooth and rough surfaces

2015 ◽  
Vol 786 ◽  
Author(s):  
J. B. Lee ◽  
N. Laan ◽  
K. G. de Bruin ◽  
G. Skantzaris ◽  
N. Shahidzadeh ◽  
...  
Keyword(s):  
Contact Angle ◽  
Impact Velocity ◽  
Rough Surfaces ◽  
Dynamic Contact Angle ◽  
Dynamic Contact ◽  
High Impact ◽  
Low Velocity ◽  
Zero Velocity ◽  
High Impact Velocity ◽  
Maximum Spreading

The maximum spreading of drops impacting on smooth and rough surfaces is measured from low to high impact velocity for liquids with different surface tensions and viscosities. We demonstrate that dynamic wetting plays an important role in the spreading at low velocity, characterized by the dynamic contact angle at maximum spreading. In the energy balance, we account for the dynamic wettability by introducing the capillary energy at zero impact velocity, which relates to the spreading ratio at zero impact velocity. Correcting the measured spreading ratio by the spreading ratio at zero velocity, we find a correct scaling behaviour for low and high impact velocity and, by interpolation between the two, we find a universal scaling curve. The influence of the liquid as well as the nature and roughness of the surface are taken into account properly by rescaling with the spreading ratio at zero velocity, which, as demonstrated, is equivalent to accounting for the dynamic contact angle.

scholarly journals Characteristics of secondary droplets produced by the impact of drops onto a smooth surface

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Haixiang Zhang ◽  
Ye Gao ◽  
Xiwen Zhang ◽  
Xian Yi ◽  
Yanxia Du ◽  
...  
Keyword(s):  
Experimental Data ◽  
Size Distribution ◽  
Smooth Surface ◽  
Average Diameter ◽  
High Impact ◽  
Solid Surfaces ◽  
Liquid Viscosity ◽  
High Impact Velocity ◽  
Secondary Droplets ◽  
The Impact

AbstractThis work investigates the splashing behaviors of droplets impacting on solid surfaces and mainly focuses on the characteristics of secondary droplets. According to the experimental results, two different splashing patterns, corona splash and levitating-lamella breakup, are observed. A new breakup mode, named rim-segmenting, is found during the levitating-lamella breakup. In particular, the detailed information of the splashing secondary droplets, including the size, velocity, angle, and total volume of the splashing secondary droplets is obtained from the experimental data. The size distribution of the splashing secondary droplets obeys the gamma distribution function. The average diameter and splashing angle of the secondary droplets are mainly related to the Reynolds number Re, and can be expressed as functions of Re. High impact velocity and liquid viscosity will result in a wider size distribution range of splashing secondary droplets. We also put forward an empirical model to predict the total splashing volume, which is consistent with the experimental data both in this work and previous studies. This work is believed to provide insights on the prediction of the characteristics of splashing secondary droplets.

Development of a Cold Spraying System for Fabricating Hydroxyapatite Coating

2012 ◽  
Vol 151 ◽  
pp. 300-304 ◽  
Author(s):  
Lei Zhang ◽  
Wen Tao Zhang ◽  
Hu Qiang Li ◽  
Wei Qiang Geng ◽  
Yong Ji Bao
Keyword(s):  
Titanium Alloy ◽  
Chemical Composition ◽  
Impact Velocity ◽  
Cold Spraying ◽  
Deposition Efficiency ◽  
High Impact ◽  
Hydroxyapatite Coating ◽  
Hydroxyapatite Coatings ◽  
High Impact Velocity ◽  
System Components

A novel cold spraying system for fabricating hydroxyapatite coatings on titanium and titanium alloy substrates is introduced in this paper. A description of the system components is presented. It is expected that the system could provide an effective method to improve deposition efficiency and compactness of hydroxyapatite coating. The addition of substrate heater helps to create dense and adherent coatings. It is found that the system could make feedstock hydroxyapatite particles be accelerated to high impact velocity. Hydroxyapatite coatings that preserve the chemical composition and microstructure of feedstock hydroxyapatite powders are obtained.

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