Papers by Keyword: Hydrodynamic Characteristics

Abstract: This paper reviews the results of research on the hydrodynamic characteristics of fine gully erosion, including parameters such as flow velocity, runoff depth and flow resistance. Experimental and simulation studies are carried out to address the problem of fine gully erosion in purple and loess areas, revealing the importance of fine gully erosion in hydraulic erosion. It has certain reference value for the establishment of hydrological and soil erosion modeling.

Abstract: This paper reports the effects of a longitudinal plate attached at the backward stagnation point of a bank of tubes on the local static pressure distribution. The longitudinal plate is termed as an integral wake splitter. Investigations on hydrodynamic characteristics of tube banks with integral wake splitter were carried out in cross flow of air in a rectangular duct at a Reynolds number of 15950. The integral wake splitter length-to-tube-diameter ratios studied were 0.5, 1.0, 1.5 and 2.0. The tube bank consisting of 12 rows and 3 tubes per row in equilateral triangular arrangement with a transverse pitch to diameter ratio, a = 2. The results obtained were compared to the experimental data of Seri et al. (2014). It is observed that the addition of the integral wake splitter reduces the overall pressure drop.

Abstract: According to the investigation and survey of the service condition of the double-block ballastless track in China, the breakage rate in the rich rainfall areas or the poor drainage lots of double-block ballastless track runs much faster than the dry areas. Some typical diseases, such as sleeper loose, contact loss between sleeper and roadbed slab, will lead to water still in the sleeper void. Free water underneath the sleepers would become dynamic water with certain pressure and flow rate under the high speed and high frequency action of train loads. Dynamic water is able to accelerate crack growth rate and scour the bonding interfaces between sleeper and roadbed slab^[1,, affecting the safety ,durability and riding quality of track structure. It is meaningful for us to research on sleeper loose of double-block ballastless track under the coupling action of train load and dynamic water and prove the mechanism of sleeper loose in double-block ballastless track under action of dynamic water. Calculating the value of water pressure and velocity of flow and then providing references for study on the hydrodynamic characteristics.

Abstract: The sea valve is a critical unit in the seawater pipelines onboard. Its mainly used to control and adjust the flux of seawater. In the practical use, the vibration and sound level of a kind of valve is proved to be too high to maintain the acoustic performance of ships.In this paper, the three-dimensional geometry and CFD model of a typical sea valve is established.Then the flow fields inside the valve, flow characteristics, drag reduction characteristics and noise characteristics were analyzed, as well as the fluid-solid coupling response between the flow field and the valve structure. Based on the analysis, two optimum schemes are proposed in order to improve the flow characteristics of the flow field and reduce vibration and noise level of this type of sea valves. The calculated results show that two optimum schemes both can improve the hydrodynamic and noise characteristics, and the scheme two is relatively better.

Abstract: The numerical simulation was used to research the effect of different head vehicles on gas curtain and hydrodynamics in the process of underwater exiting tube and movement in water and exiting water under gas curtain launch. The two different heads of the vehicles could both smoothly pass through the narrowest place of the gas curtain and enter into the gas curtain jointed with air. Head type has little influence on the state and shape of the gas curtain and on the hydrodynamics. The drag coefficient is smallest and changes stably in the process of exiting water.

Abstract: Studying the hydrodynamic characteristics of the sloping breakwater of circular protective facing by physical model test and taking a numerical simulation analysis of current field around the circular protective facing with holes under wave action by FLOW—3D.

Abstract: By the2-D tidal flow mathematical model, Calculation and analysis of hydraulics r Characteristics of the Longkou ine LV four port rcclamaiton project;and the relationship between the fill area and the width of of longkou. Research shows that, after the completion of an embankment, with the inning area fill, Longkou velocity gradually decreases. In I, II area harbor dam is formed, When the fill range from Longkou 1km ,and the Long kou width is reduced to 50m, I, II zone Longkou maximum velocity were 1.42m /s、1.54m / s, can meet the requirements of the closure gap.when III area harbor dam formed,if the fill maximum range from Longkou 1km, then closure-gap width at least to maintain 200m; for closure-gap width below 100m, then in the north and south area at the same time need to built bank. The ebb tide duration of the Longkou greater than the flood tidal duration;during the ebb tide, flow velocity basically stable, relatively small, Longkou closure should be selected during low tide and the low tide period.

Abstract: Spouted bed with porous draft tube is an improved type of conventional spouted bed which is a special kind of fluidized bed. Hydrodynamic characteristics are vital to design and normal operating of spouted bed with porous draft tube, but less research has been carried out. Two key hydrodynamics factors including maximum spouted bed height and minimum spouting velocity were studied by a series of experiments. The effects and mechanisms of features of draft tube including diameter, installing position and hole opening ratio on hydrodynamics factors were analyzed. The results are of great value to the design and optimization of spouted bed with porous draft tube and broad the engineering application sphere of spouted bed.

Abstract: This paper describes the latest research progress of the hydrodynamic characteristics of structures exerted by internal waves in a continuously stratified fluid. In particular, the research of internal waves in the two-layer fluid has done a detailed description.

Abstract: The influence of different the depth to the hydrodynamic characteristics of the underwater cylinder vertical launch out of the tube was researched with numerical simulation. The finite volume method based on the multiphase model, continuity equation, transport equations of liquid mass fraction,a dynamic mesh technique and a standard tow-turbulence model are adopted to solve RANS equation in conjunction. The fluid-solid coupling problem of both movement boundary of the cylinder and multiphase flow field was solved by using numerical method. Under the influence of the gravity, the flow field affected the hydrodynamic characteristics of the cylinder was derived with the numerical simulation. Simulation results show that different launch depths affect on the trajectory of underwater cylinder and hydrodynamic. The fluctuation reasons of different pressure drag coefficient, viscous drag resistance coefficient and toll resistance coefficient were derived by analyzing simulation results.