Water temperature influence on the spherical body’s falling velocity

Gylys, J.; Skvorčinskienė, Raminta; Paukštaitis, Linas; Gylys, M.; Adomavičius, Arvydas

doi:10.1016/j.ijheatmasstransfer.2015.05.111

Cited by 12 publications

(11 citation statements)

References 10 publications

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“…Recent studies have presented that the vapor layer formed in the film boiling regime can also be used to reduce the pressure drag caused by the difference between pressures in the front and the rear of the object. [15][16][17][18][19][20] Vakarelski et al [17] investigated the drag reduction effects of the vapor layer when a free-falling sphere reached its terminal velocity in a fully fluorinated liquid with a low boiling point and a low latent heat of vaporization against water. They conducted the experiments in the subcritical range of Reynolds number, where the pressure-induced drag accounted for more than 95%.…”

Section: Introductionmentioning

confidence: 99%

Drag reduction characteristics of heated spheres falling into water

Jia-chuan¹,

Wei²,

Xia³

2018

Chinese Phys. B

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We experimentally investigate the drag reduction characteristics of heated spheres falling into water by using a highspeed camera. In 25-• C water, with the increase of the sphere temperature the average velocity increases to a maximum value at a temperature of 400 • C and then decreases until the temperature reaches 700 • C, the average velocity will increase while the sphere temperature continually rises until the temperature reaches 900 • C. The average and the maximum velocity of the heated sphere are larger than those of the room-temperature sphere. The flow separates at the rear of the heated sphere, leading to low pressure drag. The drag reduction effect of the stable film boiling is lower than that of the nucleate boiling. In the nucleate boiling regime, the average velocity decreases with the increase of water temperature, the drag of the sphere with gentle boiling intensity is smaller. The vapor layer formed in the stable film boiling regime can improve the stability of the fall trajectory. The intense turbulence caused by the nucleate boiling can make the sphere largely deviate from rectilinear motion.

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Section: Introductionmentioning

confidence: 99%

Drag reduction characteristics of heated spheres falling into water

Jia-chuan¹,

Wei²,

Xia³

2018

Chinese Phys. B

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“…(Vakarelski et al [10], Linke et al [11]). Application of the boiling crises (film boiling) may be considered as one of the newest technologies allowing reduction of the body's resistance [10,[12][13][14][15][16]. Steam film (layer), generated on a hot body's surface, separates the body from the main volume of the liquid; therefore, a resistance reduces sufficiently and the body's velocity increases.…”

Section: Introductionmentioning

confidence: 99%

“…Certain works [12][13][14][15][16] were dedicated to the numerical and experimental investigation of drag force reduction and velocity increase during the falling process of the spherical and cylindrical bodies in water under different body and water temperatures.…”

Section: Introductionmentioning

confidence: 99%

“…Gylys et al [16] investigated dependence of the falling velocity on the spherical body temperature for the water temperature 14 • C. It was found that the intensive steam generation has a significant influence on the falling velocity. Furthermore, the range of the body surface temperature (300-400 • C) was determined where the falling velocity was the highest.…”

Section: Introductionmentioning

confidence: 99%

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The Influence of Boiling on the Streamlined Body Drag Force and Falling Velocity

et al. 2021

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This article presents the results of numerical investigation of the influence of the streamlined body temperature on drag force and on the falling velocity in a water channel. The experimental data reflecting the cooling dynamics and body temperature influence on the falling velocity are presented as well. k − ε turbulence model and homogenous heat transfer model were chosen for the numerical 3D simulation. Drag force changes induced by the alteration of the body temperature were investigated. Velocity of the streamlined body under different temperatures of water was investigated experimentally, and the results were compared to the data obtained during the numerical simulation. The increase of the falling velocity and decrease of drag force were found to have been affected by the increase of the body temperature, which had influence on the change of the water parameters (density, phase, etc.) near the surface of the body. Simulation showed that the drag force and a velocity also depended on the water temperature. The drag force of the streamlined body decreased by 32% in comparison to the cold body for the body temperature equal to 150 °C and water temperature close to the saturation temperature (98 °C). Experimentally, it was determined that the velocity of the streamlined body covered by vapor film depended on the falling time and increased by 10–30%. Velocity difference was very small for the cold and hot bodies at the initial moment of the drop; however, it reached 20% and more after 0.3 s of the falling process.

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“…Gylys et al [21] and Vakarelski et al [22] presented that the Leidenfrost effect can be used to reduce the drag of the sphere falling in a liquid. Vakarelski et al [22] argued that the presence of the vapor layer can make the flow separation point move to the rear hemisphere, leading to the reduction of pressure drag which accounts for most of the total drag in their study.…”

Section: Introductionmentioning

confidence: 99%

Cavity formation during water entry of heated spheres

et al. 2018

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We experimentally study the cavity formation when heated spheres impact onto water at low and high subcooling. The observations present that the formation and appearance of the cavity are affected by the boiling modes and the heat transfer intensity. In the nucleate-boiling regime, a rough cavity can be formed at a rather low impact velocity, while at the same velocity, the cavity formed in the film-boiling regime may have a very smooth interface with a stable vapor layer around the sphere. We discuss the effects of the impact speed, water and sphere temperatures on the stability of the vapor layer. For low subcooled water, the stable vapor layer will be disturbed when increasing the impact velocity, leading to a disturbed cavity. For high subcooled water, the film boiling has a particular boiling model in which the vapor layer around the sphere cannot keep its stability. In this particular film-boiling regime, no cavities can be formed at low impact velocities and only broken cavities can be formed at high impact velocities.

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Water temperature influence on the spherical body’s falling velocity

Cited by 12 publications

References 10 publications

Drag reduction characteristics of heated spheres falling into water

Drag reduction characteristics of heated spheres falling into water

The Influence of Boiling on the Streamlined Body Drag Force and Falling Velocity

Cavity formation during water entry of heated spheres

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