Conductivity Signal Distribution Law for Surface Ship Wake
Chen Boyi,Li Baoguo
(College of Ship and Power, Naval University of Engineering, Wuhan 430033, China)

Abstract: Velocity and salinity (or density) differences between the wake area and non-wake area of a surface ship may be measured with an electric c onductivity probe. A salinity-stratified fluid field similar to the ocean envir onment, is simulated in a water tank, and the wake is resulted from a self-prop elled, dual-propeller surface ship model. The lateral distributions of the cond uctivity signal of the wake are investigated respectively in the salinity-strat ified fluid and a non-stratification homogeneous fluid and a numerical evalua tion is carried out for the longitudinal velocity distribution of the surface ship wake in the salinity-stratified fluid. The results indicate that the wake conductivity signals obey approximately Gaussian Distributions along the lateral direction in both salinity-stratified fluid and the non-stratification homogene ous fluid, the effect of the wake velocity on the conductivity signal is much greater than that of the salinity gradient. The nondimensional longitudinal veloci ty loss of the wake coincides with the measurement of the lateral distribution of the relative wake conductivity signal very well.
Keywords: surface ship, wake, salinity stratification, conducti vity signal.