Research On Ship Model Resistance Performance And Speed Correction Method Under The Influence Of Blockage Effect

In recent years,the relevant departments of our country have issued some relevant regulations on energy saving and emission reduction of ships and ports in combination with international regulations,and attach great importance to the green development of ships.With the development trend of large-scale,rapid and high-performance ships,the Research problems have become popular research topics.The main method to study ship performance is experimental research,including model towing tank test and real ship seaworthiness test.The real ship cost is high,the cycle is long,and the test process is difficult,which makes the ship model test become a necessary means.The test of the ship model in the towing pool will be limited by the boundary of the side wall and the bottom of the pool,which affects the actual resistance performance of the ship model.Especially in order to reduce the scale effect of the ship model,the scale of the ship model is getting larger and larger,resulting in The blocking effect produced by the pool is getting more and more serious,affecting the performance research of the ship model.In order to solve this problem,this paper selects two ship models with different scale ratios,DTMB5415,to study the blocking effect,and explores the reasons why the blocking effect causes the ship model’s backflow velocity,which leads to the increase of the water velocity around the ship model,and the ship model speed is corrected.As far as possible,it is consistent with the resistance curve of the ship model sailing in open water.The research on the blocking effect of the pool is mainly from the comparative study of experiment and numerical simulation.In terms of testing,it mainly conducts research on the conventional resistance of the ship model,measuring the resistance,heave and trim of the ship model,studying the influence of the tank on the blocking effect of different scale ship models from the attitude,and observing the sailing of different scale ship models in the pool The extent to which the ship’s waves are affected by the pool.Using PIV fine flow field measurement technology to measure the flow field of each section of the ship model,study the influence of the pool blocking effect on the micro flow field of the ship model,measure the change of the flow field of the same section at different speeds and the same number of different ship models Changes in the flow field.In terms of numerical value,numerical calculation software is mainly used to carry out numerical simulation and infinite water simulation of test conditions.First,from the aspect of resistance,the frictional resistance and residual resistance of the ship model are calculated and analyzed,and it is judged that the ship model will block when the speed is different.The degree of influence of the effect on the resistance component of the ship model.The posture of the ship model is simulated and compared with the experimental data to explore the influence of the blocking effect of the ship model with different scale ratios in the same water area and the influence of the blocking effect of the same ship model in different waters.Secondly,in terms of the mechanism of action,numerical simulation is mainly used to simulate and calculate the free surface of the ship model to study the influence of the blocking effect on the free surface of the ship model.The wave amplitude changes around the ship model cause the change of the free surface.Comparative analysis of the ship model when sailing in pools and infinite waters,resulting in pressure changes at the bottom of the ship model,the stern and the ship Bow pressure changes;to study the effect of blocking effect on the flow field around the ship model,select multiple cross-sections,longitudinal sections and horizontal cross-sections,mainly to compare the flow fields around the bow,stern and bulbous bow to explore the blocking effect on the ship The influence of the flow field around the mold.Finally,the main research is on the increase in the velocity of the ship model caused by the blocking effect of the pool.The blocking effect causes the ship model to produce a backflow velocity.The acquisition of the backflow velocity is the main key to correct the velocity of the ship model.The existing international velocity correction formula is analyzedCarry out the correction calculation on the ship model and compare the advantages and disadvantages of each correction formula.Using the mean flow theory to establish the correction formula of the ship model,find out the correction formula of the towing tank of Harbin Engineering University,and finally establish a map suitable for the towing tank correction method.