Analysis On The Effects Of The Bend Head On Flow Characteristics And Ship Around The Spur Dike

In waterway regulation and flood control and river control engineering,bend head spur-dike as regulating buildings were widely adopted. Previous studies on the bend head spur-dike more focused on the recirculation zone behind the spur-dike and scour, etc.and few study about its influence on navigation condition. Bend head for different lengths of groins, analysis of changes in flow characteristics and properties of the force near the ship around groins, can provide a scientific basis for the design and operation of the ship channel regulation. And it is of significance for water transport accidents control and water transport efficiency improvement.On the basis of summarizing the research status at home and abroad, using RNG turbulent model and ship model experiment, analysis and experiment research on the flow characteristics around the spur dike and mechanical characteristics of ship through the spur dike, study the influence of bend head on the navigation condition near the spur dike.Get the following main conclusions:(1) Under the influence of the bend head, the longitudinal flow velocity decreases in the area away from the dike head; high flow velocity concentrates towards the dike.These provide a more favorable conditions for the safe navigation of the ship.(2) Bend head has the effect of guiding along the flow, speeding up cross-flow rate of decay and reducing the effects of cross-flow. If more than 0.3m/s transverse velocity region for unsafe region,when the bend head lengths are 1/3D,2/3 D and D, the distance from the location of tranverse velocity decay to 0.3m/s to the dike head at the dam axis transverse direction is shortened by 8.5%,11.9% and 17.8%, with an area behind the dam axis velocity than 0.03m/s, respectively, decreasing by 14.8%,27.8% and 39.7%.(3) Under the influence of the bend head, upstream and downstream water level biggest difference decreases with the increase of the length of the bend head. When hook length L comes to an D, upstream and downstream water level general largest decrease 12.2%, can provide favorable conditions for navigation of ships.(4) Ship lateral force as it passed the spur dike will experience two positive pushing peak and a negative absorption peak, and the first positive peak is greater than the second. The first positive pushing peak appears when the ship move upstream from 0.06 to 0.17 times captain range, the closer the transverse distance between ship and dike hand,the greater the peak value. The first negative position peak appears when the ship move downstream from 0.11 to 0.44 times the captainmThe more the ship farther away from the dike head,the more later the peak appears and more gradual its force change is. The two peak value is proportional to the velocity index. Ship transverse distance nearer the spur dike, the transverse stress changes more rapidly, adverse to the ship maneuvering further.(5) The stress variation law with the bend head spur dike and spur dike is similar, but the peak value is different. Bend head can reduce the positive peak lateral force effect, but when distance of the ship lateral from the spur-dike is constant, increasing the bend head will increase the adsorption by bend head. When the bend head length reaches 1/3 dike length, its range of impact on the ship in the transverse direction will not exceed 1/3 dike length.(6) The longitudinal force on the ship in the water embodies the change of resistance when the ship pass by the spur dike. When the ship center is located in the downstream of 0.06-0.28 times the range of spur dike, longitudinal force extremes appears.When the flow velocity and the transverse distance between ship and dike head remain unchanged, ship longitudinal force decreases along with the bend head growth.When the bend head length L reaches D, the longitudinal force is reduced by 14.8%.