Advanced Materials Research Vols. 516-517

Abstract: Inner flow field, pressure field and gas phase concentration of the gas-liquid cylindrical cyclone (GLCC) was studied and simulated with a Fluent soft pack by means of Computational Fluid Dynamics (CFD). Distribution characteristics of pressure drop and velocity field of the GLCC reveal that the inlet position and the outlet diameter of overflow can affect its separation performance. Low pressure drop and high separation efficiency can be obtained by designing the inlet position and the overflow tube diameter.

Abstract: A model of coalescing helical pipe is established through the analysis to the oil phase in continuous water phase inside a helical pipe, by using Fluent software. The influence of structural parameters and operation parameters of helical pipes on oil droplet coalescing effect is verified. Results show that the oil drop coalescing effect increases with the rise of gyration radius and number of turns of helical pipe, and decreases with the rise of the helical pipe diameter and inlet velocity.

Abstract: Effect of no-dimension parameter Peclet number describing the hydrodynamic behavior on pollutant removal is studied experimentally in a specially designed reactor with compound flow pattern of plug-flow, baffled-flow and mixed-flow. A set of orthogonal test is arranged to examine the relationship between Pe number and removal efficiency of pollutant and it is shown that there is an optimum Pe number of 1.38 at which best removal rates of COD, NH4+-N and TP are obtained, also the mechanism is analyzed briefly.

Abstract: Due to safety consideration of storage and transportation of liquid fuel at low atmospheric pressure region, the influence of low atmospheric pressure on heptane jet fire was numerically investigated, based on LES and mixture-fraction combustion model. Injection heptane diameters satisfy Rosin-Rammler distribution. The simulation shows that, low atmospheric pressure has an evident effect on jet fire. It extends the fire length and shortens the lift-off height. The centerline temperature rises to the maximum value more rapidly and then it decays more slowly. The maximum centerline temperature is not sensitive to various atmospheric pressure.

Abstract: Based on computational fluid dynamics (CFD) method, applying FLUENT software, taking a de-oil hydrocyclone as an original structure, the effect of porous overflow pipe on the performance and pressure characteristics is analyzed. Effect of overflow-pipe length and diameter of the porous overflow-pipe (POP) hydrocyclone is studied. It is found that the extension of overflow-pipe length can play a coalescent role; the new type hydrocyclone can increase oil content around overflow outlet so as to be beneficial for the enhancement of separation effect.

Abstract: Membrane bioreactor flow field distribution directly affect effective control of the membrane pollution,and affect the membrane flux greatly. The experiments of membrane bioreactor liquid are measured by using PIV that the measurement areas include membrane bioreactor upper, middle and lower. The experimental data obtained velocity field information through the PIV software analysis. The experimental result indicates that middle of the membrane bioreactor flow field is the most unstable. The experimental measurement result provide membrane bioreactor structure the optimized design, effective control of membrane pollution and raise the membrane flux.

Abstract: In order to study the mechanism of gas-liquid two-phase flow, a method of characteristic variables extracting based on Adaptive Optimal-Kernel (AOK) theory was represented in the paper. First, to collect dynamic differential pressure signal of gas-liquid two-phase flow through a horizontal V-cone flow meter, and then the AOK theory was used to analyze the dynamic differential pressure signal. The movement law of two-phase flow was discussed through the time-frequency spectrum. Finally, four characteristic variables were defined by using the time-frequency spectrum and the ridge of AOK. After the characteristic variables were visual analyzed, the relationship between the different combination of characteristic variables and the flow pattern was obtained. The results show that, characteristic variables defined by this method can get a clear description of the flow information. This method provides a new way for the flow patterns identification.

Abstract: The primary energy losses of electric submersible pump (ESP) are waterpower loss and volumetric loss. Owing to the limit of current casting technique of the ESP impeller, some fractions of casting residua will be settled in the flow passage of impeller and cause local jam-up in the flow passage, which will increase additional waterpower loss and reduce the pump efficiency. Because of the complicated structure of ESP impeller, conventional nondestructive testing (NDT) is difficult to inspect the defects fast and efficiently. Fluid energy analysis method based on the boundary layer theory and the flow resistance theory analyzes the fluid kinetic energy loss caused by obstacles in the flow passage of impeller and the change of flow rate caused by the change of flow resistance. Based on the similarity principle of fluid movement, abnormal change of waterpower construction in flow passage of impeller can be reflected by measuring and analyzing the impact pressure change generated by flow rate of each flow passage using air as flow medium. The theoretic analysis and experimental results show that this method can identify the defective impeller quickly, efficiently and correctly and will be of some revelatory action on measuring the waterpower structure change of complicated impeller machinery with small size.

Abstract: Laboratory experiments using Nortek Doppler Velocimeter were performed to investigate the characteristics of water flow in open channels with submerged flexible vegetation in different arrangements. Test results reveal that the presence of vegetation influences water level variation. No matter what kind of arrangement the vegetation is, the water level variation of vegetation area can be divided into three processes: rise, and then fall, at last remains stable. While the variation ranges of water level in interlaced arrangement vegetation area is larger than the standard arrangement. Compared with standard arrangement, the water flow velocity of interlaced arrangement fluctuates much more greatly. The higher density of equidifferent vegetation area, the lower lodging degree and water flow velocity. The lateral water flow velocity fluctuates most greatly in densely vegetation area, while at sparse vegetation area, the lateral water flow above and below vegetation layer is reverse.

Abstract: The wave numerical forecasting model is based on the third generation wave model WAVEWATCHIII, which the analysis wind field of NCEP and the mixed wind field of QSCAT/NCEP are used as the forced field. With the same parameters, the wave model WAVEWATCHIII is established in wave field simulation to China seas. The analysis data of effective wave height from the National Oceanic and Atmospheric Administration (NOAA, USA) is adopted as the verification. It shows that the WAVEWATCHIII model is good agreement with the wave field date using two input wind data. And the QSCAT/NCEP is higher agreement with field data, which means that it is more suitable for wave numerical simulation for China seas.