The Momentum Hydro Hook Support, the HHS, is a totally new damping concept for vibration damping subsea. It utilizes a novel damping technique, through which the damper’s geometry separate the hydrodynamic mass turning it into a reaction mass. Simplified one can say that it captures the surrounding water, turning it into a damping mass and literally «hooks» the pipe to the surrounding water.
It is a universal vibration damper well suited for subsea flexibles and appications such as flex-loops, jumpers, risers and transport pipes that are exposed to flow induced vibration (FIV) and vortex induced vibration (VIV). The HHS is clamped to the pipe and needs no foundation, it is a passive system with a minimum number of parts and there is possibility for retrofit of the damper. In other words, do the HHS has many attractive attributes. The concept is patented, US11492773B2.
The damping effect of the concept is demonstraded through video-based measurements below, during a small-scale test.
HHS going fleixible: HHS Flex
An improvement of the HHS damper concept, is the HHS Flex, which implies variations to some of the HHS components and their properties.
For instance, the sealing that may be realized as a rubber bellow, hose or other flexible geometries and materials, may also be orientated longitudinal with the structure. Further may the sealing also act as a spring element for the vibration damper assembly. The sealing may also not act as a spring element for the vibration damper assembly.
Another variant is that the outer cover, that according to the HHS may be made of both rigid and flexible materials, is realized by a rubber bellow or hose. Such flexible outer cover can act as a spring element for the vibration damper assembly. A flexible cover may also not act as a spring element for the vibration damper assembly.
For the HHS Flex both outer cover, sealing and spring element may be realized through the same design element.
Illustrations of the flexible concept as below:
