Experimental investigation of passive cavitation control on a cylinder using proper orthogonal decomposition

Cavitation is known for its hazardous effects such as material erosion, noise, vibration and drop in efficiency hydro turbomachines. There are various approaches to control cavitation: surface roughness, cavity (CG), obstacles, and ventilation with air/water jetting. In the present work, we are aiming to examine cavitation suppression by using riblets on the surface of a circular cylinder. The experiment will be out for two kinds of scalloped riblets, horizontal (SC-H) and vertical (SC-V), and compared without cylinder (plain) at Reynolds number 1 x 105. The local force is measured by using a load cell and pressure is monitored through a pressure sensor. The cavitation structures are first captured through speed camera and analyzed through image processing by using Matlab. It is found that the lift force amplitude varies from 1.2 N of the plain cylinder to 0.57 and 0.48 N for the cylinder with horizontal and vertical respectively. The dynamics of the cavity behind the cylinder are visible in the time-averaged mean image. image is separated into three regions for a more in-depth examination: the far field, the center field, area adjacent to the cylinder. This serves to highlight certain important facts about cavity dynamics. to emphasize the spatial and temporal dynamics of coherent structures, the proper orthogonal decomposition (POD) is used. It is discovered that the POD modes of coherent structures can be well explained by the modes. Furthermore, it is found that while SC-V is capable of stabilizing the cavitation structures by fragmentation, SC-H substantially controls the cavitation and chaotic behavior.