Other Sources of Motion-Induced Noise in a Towed ELF H-Field Antenna

摘要

Other modes of cable vibration are compared, in their production of motion-induced noise, with the pure flexing mode. It is shown that the other modes are either negligible or can easily be made so. Earlier work of Pelios on the same problem is extended to yield an explicit quantitative result which is consistent with this conclusion. To effect the comparison, the magnitude at the cable surface of the shear fluctuations relative to the pressure fluctuations must be evaluated. This is done using the theory of turbulent boundary layers and also, separately, by using strain-gage measurements taken on a towed cable. Both methods produce the same result. The engineering theory used for the analysis is compared with a theory using the exact equations of elasticity and found to be entirely adequate for the purpose. (Modified author abstract)