Patent Grant
4853900
The invention described herein may be used by and for the Government of the United States of Amreica for governmental purposes without the payment of any royalties thereon or therefore. The present invention relates generally to immersible apparatus and more particularly to the attenuation of motion which is encountered by such apparatus due to flow fields occurring in the liquid medium and surface swells occurring thereon. Immersible apparatus, such as hydrophones, is often suspended on a cable for intended orientation along a substantially vertical axis in a liquid, with the functional purpose thereof being related to such endeavors as oceanographic research, marine seismology or underwater search operations. Such apparatus is often deployed from a drop package and can best be utilized when the position thereof is substantially static in the liquid. However, the position of such apparatus is subject to constant change when the liquid is a large body of water, such as an ocean, wherein currents tend to strum the suspended cable which causes vibratory motion therein and surface swells tend to move the suspended cable along the substantially vertical axis. Measures are known for reducing the effects of surface swells and/or strumming. In regard to the latter, elasticity in the structure supporting the apparatus suspension cable is combined with the weight and/or drag of that cable to stabilize the vertical position thereof, while a fringe is commonly disposed along the length of the suspended cable for damping purposes in regard to the former, as disclosed by U.S. Pat. No. 3,696,325. Furthermore, a hydroplane extended from a streamer cable, as disclosed by U.S. Pat. No. 3,354,860 could be utilized to reduce the effects of both surface swells and strumming. Other more sophisticated suspension cable stabilizing schemes are known but include many individual parts which must be assembled and occupy space in the drop package. Therefore, both the manufacturing costs and packaging volume of such suspension cables are considerable which disfavors the utilization thereof. It is the general object of the present invention to provide a substantially motion stabilized cable for suspending immersible apparatus. It is a specific object of the invention to avoid vibratory motion in accordance with the above stated general object by precluding vortex shedding from the cable. It is another specific object of the present invention to substantially reduce the vertical motion of the cable, in accordance with the above stated general object, when swells occur on the liquid surface. These and other objects are accomplished in accordance with the motion stabilizing concepts of the invention by enclosing the suspension cable about its longitudinal axis to provide isolation from any flow fields in the liquid. When the apparatus suspension cable is elastically supported from a flotation device, vertical motion thereof resulting from surface swells is attenuated by precluding flow through the cable enclosure to increase drag in either vertical direction. The scope of the present invention is only limited by the appended claims for which support is predicated on the preferred embodiments hereinafter set forth in the following description and the attached drawings wherein like referenced characters refer to like parts throughout the several figures.
| Number | Name | Date | Kind |
|---|---|---|---|
| R28671 | Widenhofer | Jan 1976 | |
| 3299398 | Hersey et al. | Jan 1967 | |
| 3354860 | Dale et al. | Nov 1967 | |
| 3372368 | Dale et al. | Mar 1968 | |
| 3696325 | Tallman | Oct 1972 | |
| 3711821 | Dale et al. | Jan 1973 | |
| 3992737 | Duel et al. | Nov 1976 | |
| 4747084 | Parlant | May 1988 |
