Numerical Analysis Of Installation Of Torpedo Anchors

The key problem of fixing the deepwater drilling platform by taut-leg mooring system is the penetration depth and bearing capacity of torpedo anchor. This paper use the numerical software to analysis the torpedo anchor’s characteristics of free falling in water and penetrating into the seabed soil, the numerical results show that the drag resistance force of torpedo anchor will increase with the increase of velocity during its movement, and the drag coefficient of anchor is not a fixed value, drag coefficient decreases with the increase of velocity, the drag coefficient of the overall change is small, so it can approximate as a fixed value in a small range of velocity variation. Under the same length to diameter ratio, torpedo anchor with a streamlined nose shape usually have a lesser drag coefficient, vice versa. The CEL algorithm can be used to simulate the process of torpedo anchor’s movement in water, the result is consistent with the theoretical calculation method. It is very fast (usually 1 seconds) of the whole process of penetration, which is divided into two phases of acceleration and deceleration, with the deceleration phase lasting longer. The resistance force increases with depth to the peak, at which the velocity is close to zero, then fall down steeply to torpedo anchor’s gravity (static resistance force). The relative depth of penetration increases with impact velocity with good linear relation. When impact velocity is constant, the relative depth of penetration decreases with the length to diameter ratio(LID). The strength parameters c and φ show great influence to penetration that the relative depth of penetration decreases with the increase of these strength parameters.