Abstract: Flow-induced vibration occurs widely in flow pipelines, and pipeline vibration signals have various frequency characteristics corresponding to different flow regimes. Therefore, an novel noninvasive approach to flow regime identification for wet gas flow in a horizontal pipeline is presented in this paper. The vibration signals were collected by a transducer installed on external wall of pipeline. Empirical mode decomposition (EMD) was used to decompose the vibration signal into different intrinsic mode functions (IMFs), and then the kurtosis of each IMF component for each experimental data was calculated. Finally, the IMF kurtosis feature vector was input to the support vector machine (SVM) to identify three typical flow regimes for wet gas flow including stratified/stratified wavy flow, annular/annular mist flow and slug flow in a horizontal pipeline 50 mm in diameter. The experimental results show that the proposed approach can identify flow regimes effectively, and the identification rate is 80.6%.
Abstract: This paper introduces a kinetic model to simulate a foam-core composite sandwich panel impacted by a solid semi-sphere. A modified Hashin failure criterion, which consider failure modes of fiber breakage, matrix cracking and matrix crushing, are implemented into the model analysis by using a self-developed VUMAT subroutine. Cohesive elements with zero-thickness are used in the composite laminates model and quadratic nominal stress criterion is used to predict the delamination initiation during the impact. A crushable foam model is used for foam core. The time history curve of contact force is obtained and shows a good correlation with the experimental data.
Abstract: The effects of well type, water extraction time and water extraction quantity on the control of bottom water coning are studied by analytical method. The results suggest that a reservoir with low vertical permeability and interlayer above the water oil contact would have good effect of water extraction and cone control. The effect of water extraction with horizontal well is better than vertical well; the earlier the water extraction is applied, the better the effect of water control is obtained; the larger the quantity of water extraction is, the more obvious is the water control effect, and water extraction time and water extraction quantity has optimal value. In addition, water extraction and cone control is not effective to all bottom water reservoirs that are developed with horizontal well. If the vertical permeability of reservoir is high and have not effective block off of interlining or interlayer above the water oil contact or the water body is giant, the water cut of horizontal well will go up rapidly and the effect of water extraction will be difficult to achieve.
Abstract: The stable wing of non-parachute terminal sensitive projectile (TSP) is a plate wing with two bent angles at edges of the plate wing, thus it looks like an S. Wings of this shape slow the TSP down during its falling process which provides asymmetric forces for it. Then stable scanning motion is realized. This paper established unsteady model of the S wing of the TSP based on CFD/CSD fluid structure interaction (FSI) and analyzed the aerodynamic characteristics of both rigid wing and elastic wing. The results show that the plate which bends towards the windward has the largest deformation. The drag coefficient of the elastic wing is smaller than that of rigid wing at a smaller attack angle while bigger at a larger attack angle. The displacement of S wing increases while the incoming velocity increases and has a tiny interaction relationship with attack angle.
Abstract: The sucker rod of artificial lift system in a deviated well is very complicated. This paper applies structural mechanics to analyze the distributed characteristics of stress along the sucker rod in a deviated well and builds a reliable model for stress calculation. Moreover, the model designs the sucker rod without neglecting the effects of the reaction forces and bending forces under the condition of 3D structure. Particularly, as for deviated wells with high kickoff point and long inclination paragraph, the model shows better calculation accuracy and reflects the actual local stresses.
Abstract: On July 22, 2013, an Ms6.6 earthquake occurred in Minxian-Zhangxian, Gansu Province, China, which caused serious damages. Because of the abundance and clear relationship with the main shocks, aftershocks sequences are typical types of behavior and provide useful data sets. To better understand the aftershocks triggering by static stress changes of the main earthquake, based on Okada’s elastic half-space model, we used accept fault plane consistent with the source and accept fault plane as the optimal models to calculate the stress changes on aftershock focuses by the Minxian-Zhangxian 6.6 Earthquake respectively. The results show that the latter model is better than former, more than 90% of aftershocks located in NWW and SEE, the stress increased areas, which is consistent with strike of Lintan-Tanchang fault (LTF), in other words, the Coulomb static stress changes of the main shock can induce the aftershocks.
Abstract: The vertical fracture was asymmetrical about the wellbore or two wings of a fracture are not certainly in a line for the complex geo-stress in the possession of fracturing of the gas reservoirs. In view of the low permeability reservoir after fracturing developing the asymmetrical vertical fracture and non-coplanar fractures, based on the non-steady seepage theory, using the potential function theory, superimposition principle and numerical analysis method, a performance prediction model for the vertical fracture in low-permeability gas reservoirs was deduced with pressure drop superposition principle. The production decline laws were analyzed by practical cases. The result shows that the initial production of the vertical fracture is relatively high but soon followed by a sharp decline. Then, the production keeps in a relatively stable state and declines slowly in the middle and later. The fracture asymmetry factor has little effect on the gas well productivity. The non-coplanar angles have greater effect on the oil well productivity in the initial stage. The more the fracture length and the bigger the flow conductivity, the higher the oil well production and the faster the decline rate will be. However, the increase amplitude will be getting smaller and smaller along with the fracture length and flow conductivity.
Abstract: The numerical simulation of a 3-D model of the internal flow field for a Vortex slurry pump has been analyzed in this paper. The impact of different solids volume fraction on the distribution of solid particle was analyzed. The expression of the pump head and efficiency was derived by the energy equation. The results show that either on the long blades or on the short blades, the content of the solid particles increases with the increasing of the volume fraction. The results by the expression of the pump head and efficiency are compared with the results of the simulations. The conclusions show that the expression results are similar with the numerical simulation results, and the main factors of affecting the inner and outer characteristics are the solid particles.
Abstract: In the engineering background of 1000 cubic meters of anchored tank, the large-scale finite element software ANSYS was used to analysis of modal and transient of oil storage tanks. Completed oil tank model and carried on the modal analysis and then vibration characteristics were gained. On this basis, considering the earthquake excitation, analyzes dynamic response of the anchored tank under seismic load. Then gained the oil tank overall structure of displacement, equivalent stress, axial and circumferential stress. From images can be analyzed that the main vibration mode is multiple circumferential wave, the stress of upper tank and its seams is the largest under earthquake loading and easy to be damaged, strengthen circle should be set up. Through the simulation analysis provided powerful basis for seismic design of the vertical storage tank.
Abstract: Kinetic energy rod (KE-rod) warheads are one of the most efficient types against tactical ballistic missile (TBM) that exist today, so the kill probability of KE-rod is extremely important. The paper firstly describes the necessity of KE-rod warhead, and then analyzes the separation velocity of KE-rod, the effective kill radius, static dispersal, dynamic kill zone, and the computational model of mathematical expectation for the hit rod number, and then presents the calculation method of kill probability for KE-rod. Finally, the kill probability of the KE-rod is simulated, the results show that the probability decreases rapidly with the increase of distance between the KE-rod warhead and the target, when the distance between the interceptor and target is less than 5 meters, the kill probability is up to 50%.