Steady State Behaviour of a Cable Used for Suspending a Sonar Body from a Helicopter.

摘要

A three-dimensional steady state mathematical model of a cable used to suspend a sonar body from a helicopter is derived. Results are presented in dimensionless form for a length of cable totally immersed in any Newtonian fluid, and may therefore be applied to a number of practical problems. Various approximations are made in order to obtain analytical solutions. The suitability of the approximations is investigated by comparing solutions of the general and approximate equations for a uniform fluid velocity. In general, where maximum angular deviations from the vertical are small, agreement is observed to be very good. Two-dimensional 'power' and 'log' laws are assumed for the wind above the sea, and a three-dimensional Ekman spiral is assumed for the sea current. For these non-uniform fluid velocities, the concept of an 'equivalent mean fluid velocity' is used to simplify greatly the presentation of results. (Author)