A Wake Measurement Using Fiber Optic Laser Doppler Velocimeter in a Towing Tank

Abstract

Investigations were made on the Laser Doppler Velocimeter (LDV) measurement in a towing tank especially with regard to the seeding technique and traversing of an optical unit. The longitudinal velocity component of the flow, on the propeller disk plane of a pure car carrier, was measured in a towing tank using a small fiber optic LDV. The water and aluminium powder mixture was injected as seeding, from the front of bow of the model ship into the flow field, and the data rate reached 10∼300 counts per second. The comparison with the 5-hole Pitot tube results showed that the wake contour with LDV is similar but slightly wider than that with Pitot tube.