# Scaled Model Simulation and Experimental Verification of Submarine Flexible Pipeline Laying System
## 3 Similarity Verification of Experimental Scaled Model
### Dynamic Similarity Simulation Verification of Scaled Model
#### 3.2.1 Similarity Verification of Dynamic Characteristics During Piping Laying  
Figure 5 is a scaled model of the constrained completion in Adams for pipeline laying. Among them, the curvature adjusting wheel, top pulley group, and top crane all use mass points to simulate the actual mass, which is fixed on top of the tower by ball joints. When the pipeline is laid, the tensioner is in working position, and the driving function of the sliding pair where the upper connecting rod is located is set to 0*time, then the length of the upper connecting rod is locked, which can calculate the force of each articulated point of the tower in the pipeline laying under the motion response of the reduced hull. In order to simulate the motion response of a pipe-laying ship to wave loads on the sea surface, the multi-degree-of-freedom driving mode in Adams can be used to drive the ship motion in the center of the ship. The time history curves of each degree of freedom motion of the scaled ship can be imported into the model in the form of spline data, and a spline function is added to the drive so that the platform can simulate the motion response of the ship. Through simulation, the force comparison diagram between the tower and deck articulation when laying pipe can be obtained as shown in Figure 6; the force comparison diagram between the tower and the support component under the tensioner support, as shown in Figure 7; the force comparison diagram between the tower and the upper connecting rod articulation of the tensioner support, as shown in Figure 8; the force comparison diagram between the tower and the angle adjustment mechanism, as shown in Figure 9.  
Figure 5: Simulation model (scaled model) in Adams. Figure 6: Force comparison between tower and deck articulation during pipe laying. From Figure 5, it can be seen that the force changes of prototype and scale model at the articulation of tower and deck are basically the same, and the change range of the whole around the average value is \(-\)7.1-10.7%. In the scale model, the average force at the articulation is 12,098 N, while in the similar transformed prototype, it is 12,089 N, with a gap of 0.07%. The articulation at the bottom of the tower is mainly subjected to vertical force, while the force in other directions is very small. In Figure 6, the average force at the articulation of the support components under the tower and tensioner bracket in the scale model is 6293 N and 6292 N in the similar transformed prototype. The difference between the two averages is very small; however, the range of variation around the average value of the scale model is \(-\)7.1-10.7%, and that around the average value of the prototype is \(-\)6.7-8.4%. As shown in Figure 7, the average force at this articulation in the scaled model is 3041N and 3363N in the similar transformed prototype. The force at the connection of the tensioner support and tower is slightly different from that in the scale model, but the force variation is generally the same. Figure 8: Force contrast diagram at the articulation of upper connecting rod of tower and tensioner support. Figure 7: Force comparison at the articulation of support components under tower and tensioner support. From Figure 9, it can be seen that the stress changes of the prototype after similar transformation at this articulation are highly consistent with those of the scale model. Figure 10 is a comparison between the pipe tension conversion simulated by [PERSON] and the results obtained by the Orca flex simulation method in [PERSON]'s article. Both are simulated with the size of the prototype. The difference is that the pipe is not modeled in Adams, but the equivalent mass of the static tension of the pipe is added to the tensioner. The simulation result is obtained by removing the influence of the self-weight of the tensioner from the stress at the connection point between the tensioner and the tensioner support. As can be seen from the figure, the pipeline tension is \(3.83\times 10^{6}\). The changes of the two are very similar.