TJ624 : Experimental investigation of surface groove and temperature on falling velocity of spherical bodies inside water
Thesis > Central Library of Shahrood University > Mechanical Engineering > MSc > 2019
Authors:
Abstarct: Today, physical changes (such as grooves, dimples, textures, vortex-generators, and etc.) in objects moving in water are considered as factors that can make a lot of changes in the hydrodynamic properties of objects. These methods are low cost, simple, and eco-friendly. in this investigation, the effect of surface grooves (horizontal and vertical grooves) and temperature on hydrodynamic performance, movement direction, fall speed, acceleration, cavity formation, cavity pinch off and hydrodynamic force coefficient of spherical bodies with a diameter of 20 mm Studied. All experiments are performed with seven sphere, and the spheres include six spheres with a surface groove with a different groove pattern and a sphere without a groove. All samples experimented with three different impact regime with Froude numbers (Fr=1,Fr=100,Fr=200), Webber numbers (W=13.6,W=1360,W=2720), Bond number (B=13.6) and Reynolds numbers (Re=702.5,Re=7025,Re=9935 For the heated tests, the surface temperature of spheres is set to 〖100〗^° C and 〖200〗^° C. he trajectory of spheres is visualized by a high-speed camera at a frxame rate of 1~2 [kfps]. The results prove in the lowest Froude number (Fr=1) increasing the number of horizontal grooves has a remarkable effect on descent performances. In the other two regimes with Froude numbers (Fr=100,Fr=200), observed that the spheres with the surface groove after impact to water surface create the noticeable cavity, while the sphere without groove create the very small cavity. Speed plots for spheres showed that the velocity of spheres with groove in these two regimes is far greater than the velocity of a sphere without groove.
Keywords:
#Water entry; Grooved spheres; Descent velocity; Cavity formation; Heated spheres Link
Keeping place: Central Library of Shahrood University
Visitor:
Keeping place: Central Library of Shahrood University
Visitor: