Analysis of sloshing in tanks using image processing

Abstract

Sloshing is referred to as the violent movement of liquid in a partially filled tank that undergoes dynamic motion. There are several examples of such types of motions. In ships, sloshing motion occur in oil tankers, liquefied natural gas carriers and large fuel oil tanks. In case of rockets, it happens in the liquid hydrogen (LOH) and liquid oxygen (LOX) containing external fuel tanks. The sloshing motion is mainly due to large dimensions of tanks with smooth plane surfaces in contact with the liquid. The tank layout fails to damp the sloshing motion of the liquid. The sloshing motion becomes more violent when the parent vehicle’s motion contains energy in the vicinity of the natural frequencies for liquid motion inside the tank. Determination of these frequencies is critical to determine the nature of fluid motion inside the tank and thereby predict impact load on the structure holding the liquid. The determination of hydrodynamic pressure on the tank walls due to liquid sloshing motion finds application in the design and construction of liquid tanks in rockets and ships. In some cases, determination of liquid motion inside the tank is also critical as it can get coupled with the parent vehicle’s motion dynamics. This paper deals with extraction of data from video recording of liquid sloshing motion inside a rectangular tank. Image processing techniques are used for this purpose. The important fluid dynamics properties which can be determined by image processing are discussed in the paper. The analysis presented is mainly for 2D motions.