Vortexing Characteristics During Draining from Cylindrical Fuel Tanks with Inclined Bottom Surface

During draining of liquid from a circular tank through an axisymmetrically placed drain port, a vortex with an air core forms. The vortex extends to the bottom port, reducing the effective cross sectional area of the drain outlet and consequently the flow rate. This phenomenon has practical relevance in the fuel feed system in space vehicles and liquid rockets. In the present study, the flow field in circular tanks with different inclined angle of bottom surface is studied to investigate drain flow characteristics and to see how the vortex pattern changes with inclined angle. Flow visualization studies using PIV to determine the flow patterns in a circular tank are carried out after imparting rotation to the liquid in the tank. Experiment results show the inclined angle equal to and greater than 20 degree, the air core is completely suppressed.