Characterisation of multiphase fluid-structure interaction using non-intrusive optical techniques

The purpose of this study is to determine experimentally the effectiveness of passive drag reduction techniques (which involve adjusting surface geometry) within a chaotic multiphase flow system. to quantify the intrusion and disturbance caused,a liquid-air blast atomiser continuously discharges within a test section of air at atmospheric pressure,with a circular cylinder placed 25 cylinder diameters (250 mm) downstream of the nozzle. this cylinder is then replaced with other cylinders which have modified surface geometry. the data was obtained using particle image velocimetry (piv) and determines the fluid motion resulting from spray structure interaction of a liquid spray with a circular cylinder. subtraction of non intruded spray images from intruded spray images at the same locations,using the time averaged analysis allows the direct comparison of the amount of disturbance each geometric variant has on the spray. using this data alongside velocity profiles time averaged trends were compared. drag reduction from v-shaped grooves provides the greatest disturbance reduction. this is due to the reduced shear stress around its cross section and the addition of small liquid eddies within each v-groove creates a gliding surface. these features proved to be most effective when monitoring drag reduction in multiphase flowstructure interaction. © school of engineering,taylor's university.