Advanced Materials Research Vols. 516-517

Abstract: Using the Fluent software, the flow field of oxidation ditch was simulated by the three dimensional turbulence mathematical model. The velocities were analyzed and measured, and the simulation results showed acceptable prediction of the velocities in the oxidation ditch. The results also showed that velocity could reach more than 0.3m/s when 8 impellers worked, and MLSS in the whole ditch were almost uniform, therefore, the oxidation ditch runs well.

Abstract: More and more attention has been attached on flow-induced noise of centrifugal pump in recent years because of strict environmental noise restrictions and demands of clients.. In this paper, the role of volute impacted on flow-induced noise generation and propagation in centrifugal pump were summarized. The process of internal wave propagation was analyzed, and the transmission coefficient and loss of volute were calculated; In order to compare the effect of volute vibration on the sound field in a centrifugal pump, a hybrid algorithm based on CFD + BEM was adopted. The results reveals that: full reflection of sound wave occurs on the fluid-steel volute wall when the incidence angle is more than or equal to 13.8 °; otherwise a sound transmission appears; For onshore pumps, For onshore pumps the A-weighted sound transmission loss is more than 55dB under the condition that thickness volute is not less than 8mm; For submersible pumps, all-bottom sound below 3000Hz almost transmits to the outside field entirely; structure acoustic coupling between volute and the internal sound field influence little on directivity of sound field and the change of law, but structure vibration would average the sound pressure level in frequency.

Abstract: The phenomenon of wax deposition is an extremely important issue in the petroleum industry. Researching it is of great help for the oil exploration, gathering, and transportation. This paper described the phenomenon of wax deposition, discussed the mechanism, analyzed the influencing factors and proposed the positive significance of the phenomenon of wax deposition on crude oil production and safe operation in oil gathering and transportation pipeline.

Abstract: In order to investigate the air injection method on the performance of an airlift. For this purpose an air lift system with a riser 2000 mm long and 80 mm in diameter, was designed and tested. Seven different air injection methods were used at a constant submergence. The experimental results showed a marked effect on the airlift performance when operated with different air injection methods. The arrangement of five nozzles gives the best performance, and the one nozzle is the worst. Although the injection angle has a little effect on the airlift performance, but view the general conclusions as a whole, the best lifting efficiency can be obtained when the angle of the nozzle placed along the tangential direction of pipe wall is equal to 10º at a given air flow rate QG =37m3/h.

Abstract: The structure and aerodynamic performance of inlet pipe which is the key component of turbine generator have direct and significant influences on the input characteristic and safety reliability of fuze turbine generator. A kind of inlet pipe structure was designed by applying the variable cross section pipe and simulated based on the inlet pipe type and application analysis of turbine generator. The results showed that the air flow pressure which the turbine generator obtained from the ballistic can be controlled in a certain range by adjusting the relative structure parameters of inlet pipe to guarantee the stable output characteristics of generator, which can completely meet the technical requirements of fuze.

Abstract: Numerical simulation of rotor oil pump is completed by using SC/Tetra under variable conditions, which obtains the distribution of pressure and velocity. The pressure in the outlet oil chamber rises with rotation of rotor which makes the space smaller and smaller. In the result of postprocessor the maximum pressure is 4.3Mpa. This paper also studies on the internal velocity field distribution of pump body and pump cover. By the chart of velocity vector, fluid exists obvious reflow phenomenon. This is because of effection of the rotor rotation. The maximum velocity mainly exists in pump cover. Futhermore, flow characteristic curve is compared with the experimental result. The result basically shows the correctness of numerical simulation.

Abstract: Extensive experiments have been carried out at an air-water loop to study the phase splitting characteristics of semi-annular flow in a new type distributor. The distributor composes eight small holes with a diameter of 3.5mm on the pipe wall and an annular chamber mounted outside of these holes. The gas-liquid mixture extracted from the holes is collected in the annular chamber and enters branch arm ultimately. Compared with conventional T-junction, the branch quality can maintain unchanged over a wide range of mass extraction rates. A model is developed to predict the phase separation in dividing semi-annular flow. The model simulation results were compared with experimental measurements, and there is reasonable agreement between model prediction and measured data. According to this model, the desired branch quality may be achieved by changing the ratio of gas flow area and liquid flow area.

Abstract: A method approaching mirror boundary condition for smoothed particle hydrodynamics (SPH) method is presented. The virtual particle is generated through the nearest boundary particle of the flow particle. The operation is relatively simple and convenient and the applicability to the complexity boundaries can be markedly enhanced. The two dimensional non-linear sloshing is simulated with the new boundary condition. The results are in good agreement with the mirror boundary condition and the boundary force condition dada. It shows that this boundary condition can work well for SPH models.

Abstract: Unmanned Underwater Vehicle (UUV), which could be used for ocean exploration and development, developed rapidly in recent years. In order to make UUV quieter to be competent for rigorous working conditions, a new propulsion with lower underwater noise must be designed. A new high-skew ducted propeller, which had the advantages of both ducted propeller and high-skew propeller, had been designed for UUV to obtain adequate thrust and lower underwater noise. CFD simulation of the high-skew ducted propeller showed that the thrust was enough for UUV working underwater and the hydrodynamic efficiency was very close to that of conventional ducted propeller. The strength of high-skew ducted propeller had been checked by FEM method, and the maximum stress would appear on the trailing side of blade on 0.5R, where the blade was unsubstantial. Underwater noise had also been measured, which proved that the high-skew ducted propeller had lower noise than that of conventional ducted propellers. As a quiet propulsion, the high-skew ducted propeller could be used on UUV or ship who want to be quiet underwater.

Abstract: Some properties of two dimensional open channel flow were studied. Energy distribution was calculated to show energy exchanging relationship between the mean flow and the fluctuating flow. Viscous dissipative energy of mean flow, the energy of fluctuating flow and the energy of fluctuating flow taking from the mean flow were calculated. The energy spectrum was explored. The mechanism of two dimensional parallel to wall shear flow were probed to show that not only the energy transfer relates different structures corresponding to different levels of turbulent exciting but also the energy dissipating and diffusing closely connect with resonant vibration and frequency-locking. On the basis of flowing structures, the results applying to waterway regulating was discussed.