Papers by Author: Yong Wang

Abstract: The experiments were conducted in a horizontal multiphase flow test loop (50mm inner diameter, 40m long) and the cross-correlation technology was used for the study of the characteristics of the interfacial wave velocity about two types of annular flow regimes (AN║DO/W and AN║DW/O) for gas-oil-water three-phase flow. The results show that the interfacial wave velocity on the liquid film of AN║DO/W flow pattern and AN║DW/O flow pattern all increases with the increase of gas superficial velocity and liquid superficial velocity on the condition of fixed ratio of oil and water flow rates, but the difference is that the increase is a linear monotonic increase for AN║DO/W flow pattern and a non-linear increase for AN║DW/O flow pattern, and the liquid superficial velocity makes a larger contribution than the gas superficial velocity. The interfacial wave velocity also increases with the increase of input water cut in liquid at different gas superficial velocities under the conditions of liquid superficial velocity fixed.

Abstract: The experiments were conducted in a horizontal multiphase flow test loop (50mm inner diameter, 40m long) to investigate the flow of oil/water and the influence of an involved gas phase with low flow rate in horizontal pipes, specifically including oil/water flow patterns, cross-section water holdup and pipe flow pressure gradient. The experimental results indicated that the involved gas with low flow rate had a considerable effect on oil/water flow characteristics, which shows the complexity of gas/oil/water three-phase flow. Thus, this effect could not be ignored in design and operation management of oil/gas gathering and transportation system.

Abstract: Experiments were conducted in a horizontal multiphase flow test loop (50mm inner diameter, 40m long) to study the flow patterns for oil-gas-water three-phase flow and the pressure gradient fluctuation based on flow patterns. Using new methods of definition, 12 types of flow patterns were obtained and phase distribution characteristics of each pattern were analyzed. A new flow pattern (SW║IN) was firstly found in this work. Characteristics of the pressure gradient based on 7 flow patterns were carefully discussed. It was found that the pressure gradient increased with the increase of gas superficial velocity and oil-water mixture velocity. However, characteristics of the pressure gradient became complex with the increase of input water cut. The influence of flow structure of oil-water two-phase should be fully considered.

Abstract: In the seismic design of pile foundation, current research mainly adopts the theory of auxiliary experiences engineering design methods. In particular ground, the pile must be specially designed to meet the seismic requirements. In this paper, with large scale finite element software ADINA,a 2-d finite element entity model is established to calculate and analyze the influence of soft soil to the dynamic interaction of soft pile-soil under the earthquake. The maximum displacements and acceleration of the measuring points on the pile are analyzed in different thickness and position of the soft soil. Calculation results show that: Soft soil effect the maximal displacement and acceleration of the measuring points on the pile which changed with the different thickness and positions of the soft soil. It should be noticed in the design of pile foundation and ground treatment.

Abstract: In this experiment Al2O3 gradient ceramics coating is cladded on the high Cr cast steel by 5kW crosscurrent CO2 laser with Ni-based alloy which is used as transitive metal. The microstructure is analyzed with optics microstructure analyzer and the crystal grain characteristic is studied. The microstructure of the laser cladding layer have the plane crystal zone, the butcher crystal zone, the dendrite zone and the surface equiaxed grain zone that grow along the substrate. The microstructure of the coating compared with the substrate is extremely tiny, and the microstructure of the multi-layer cladding presents stratification. The phase composition of the clad coating is composed primarily of NiAl intermetallic compound, but also includes γ-FeNi and a little Ni3Al compound. In the coating the Al2O3 pellet that some present the unit crystal form, and some little accumulate in together, plays the dissemination strengthening role in the coating material. The massive twin crystals and the dislocation staffing are presented in the clad coating.

Abstract: In-service welding is a kind of important method to ensure the integrality of oil gas pipeline and the thermal cycle of which is significant for repairing. Used SYSWELD to establish model and simulate thermal cycle of in-service welding on X70 steel gas pipeline, compared thermal cycles of in-service welding and air-cooling welding, studied the influence of gas pressure and flow rate on thermal cycle. The result shows that peak temperature of the coarse grain in heat affected zone (CGHAZ) of in-service welding is similar to air cooling welding, but the cooling time of t8/5, t8/3 and t8/1 decreases at certain degree. Peak temperature of CGHAZ of in-service welding doesn’t vary match with gas pressure and flow rate either. t8/5, t8/3 and t8/1 decrease when gas pressure increases. t8/5 varies with the gas pressure linearly. When the pressure is less than 4MPa, t8/3 and t8/1 decrease rapidly while gas pressure increases. When the pressure is more than 4MPa, t8/3 and t8/1 decrease slowly while gas pressure increases. t8/5, t8/3 and t8/1 decrease when the flow rate increases. When gas flow rate is less than 10m/s, t8/5, t8/3 and t8/1 decrease rapidly while flow rate increases. When gas flow rate is more than 10m/s, t8/5, t8/3 and t8/1 decrease slowly while flow rate increases.

Abstract: Laser surface melting has been performed on high chrome steels by a 5kW CW CO2 laser using different overlapping ratios. The microstructures of laser melted steels were analysed by SEM and the hardness profiles were determined by a Vickers hardness tester. The corrosion characteristics of laser melted steels in 3.5% NaCl solution were studied by electrochemical corrosion equipment. The melted zone of a single laser track exhibits a mixed structure of dendritic, cellular and equiaxed austenite while the overlapped melted zone is only composed of austenitic dendrites. Using a large overlapping ratio (OR) gives a more uniform hardened-depth. The microhardness with an OR of 33.3% is higher compared to 16.7% and 50%. The corrosion resistance of laser melted steel is improved arising from the dissolution of carbides, the increasing of alloying elements in the solid solution and the large amount of austenite. Among all the studied specimens the one, which is laser treated with 33.3% OR presents the better corrosion resistance.

Abstract: In order to improve surface properties, high chromium austenitic base heat-resistant cast steel was scanned with a 5kW continuous wave CO2 laser, the specimen was aged at the temperature of 600°C~900°C. The microstructure and phase composition of the specimen were analysed with optical microscopy, electronic microscope and X-ray diffractionse. The hardness was measured. The results show that as-cast structure of high chromium cast steel is coarse and non-homogeneous, and mainly consist of austenite, ledeburite and carbides. After laser surface melting, the section is divided into the melted zone consisted of fine austenite and carbides, the heat affected zone composed of austenite and eutectic carbides, and the base meta1. The melted zone is very fine structures with dendritic crystals, only at the bottom a cellular structure is observed. A continuous carbide network is located in the austenitic grain boundaries at the heat affected zone. Carbides particles distribute dispersed out, the hardness of melted zone increases 35% than the base metal after aging. The area and the hardness of various zones are related to the laser processing parameters. The hardening depth of melted zone and heat affected zone may be up to 200μm~300μm.

Abstract: An unequal interval grey forecast model GM (1, 1) was proposed based on the grey system theory and the measurement data of the rate of high temperature abrasion of water-wall tubes in circulating fluidized bed (CFB) boilers. According to the former part of measurement data, the latter part of high temperature abrasion rate of water-wall tubes was forecasted by using the GM (1, 1) model. Through comparing the computation values with the measurement values, the accuracy and the feasibility of the model were verified. The result shows that under small statistics conditions, the unequal interval grey forecast model can offer precisely prediction results, which can provide scientific basis and guidance for the condition-based maintenance of the water-wall tubes in CFB boilers.