Abstract
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.
Highlights
Reduction of the body drag, moving in a liquid, is one of the main problems in various areas of the engineering and technology
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
Summary
Reduction of the body drag, moving in a liquid, is one of the main problems in various areas of the engineering and technology. 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. In the case of the hot body, the steam isolated the surface from the main flow of the liquid; the drag force was lower than for the cold body. Steam generation at the tail part of the hot cylindrical body caused more intensive abruption of the liquid in that area and, lower drag force and higher velocity. This article is dedicated to the numerical and experimental investigation of the influence of the streamlined body temperature influence on drag force and on the falling velocity of the body in a water channel
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