Numerical simulation of 80 ℃ temperature field distribution of thick plate multi-pass welding with SYSWELD

The PPG PITT-CHAR XP flame retardant system has been used by COOEC to preventing the thermal softening of steel in the high temperature,whose degradation temperature is 80 ℃.To prevent damage to PPG PITT-CHAR XP fire retardant paint from excessive heat during welding,it is necessary to get accurately reserved area near the welding joints prior to welding. For the foregoing reasons,the 80 ℃ temperature field distribution of thick plate multi-pass welding was analyzed with SYSWELD.The influence of welding groove form and time interval on welding temperature field was also analyzed. Results showed that the range of 80 ℃ welding temperature field increased with the increasing of weld layers at first and then it inclined to stable value. Interpass time setting was crucial to control the range of 80 ℃ welding temperature field. It was also found that double V groove had better thermal diffusivity than double-bevel groove.And double-bevel groove was better than single V groove.

Influence of porosity distribution on nonlinear free vibration and transient responses of porous functionally graded skew plates

This article deals with the investigation of the effects of porosity distributions on nonlinear free vibration and transient analysis of porous functionally graded skew(PFGS)plates.The effective material properties of the PFGS plates are obtained from the modified power-law equations in which gradation varies through the thickness of the PFGS plate.A nonlinear finite element(FE)formulation for the overall PFGS plate is derived by adopting first-order shear deformation theory(FSDT)in conjunction with von Karman’s nonlinear strain displacement relations.The governing equations of the PFGS plate are derived using the principle of virtual work.The direct iterative method and Newmark’s integration technique are espoused to solve nonlinear mathematical relations.The influences of the porosity distributions and porosity parameter indices on the nonlinear frequency responses of the PFGS plate for different skew angles are studied in various parameters.The effects of volume fraction grading index and skew angle on the plate’s nonlinear dynamic responses for various porosity distributions are illustrated in detail.

NUMERICAL STUDY ON FLOW DISTRIBUTION IN PLATE-FIN HEAT EXCHANGERS

Objective To investigate the flow distribution in plate fin heat exchangers and optimize the design of header configuration for plate fin heat exchangers. Methods A mathematical model of header was proposed. The effects of the header configuration on the flow distribution in plate fin heat exchangers were investigated by CFD. The second header configuration with a two stage distributing structure was brought forward to improve the performance of flow distribution. Results It is found that the flow maldistribution is very serious in the direction of header length for the conventional header used in industry. The numerical predictions indicate that the improved header configurations can effectively improve the performance of flow distribution in plate fin heat exchangers. Conclusion The numerical simulation confirms that CFD should be a suitable tool for predicting the flow distribution. The method has a wide variety of applications in the design of plate fin heat exchangers.

Distribution of Inherent Strains and Residual Stressesin Medium Thickness Plate Weldment

A fundamental theory for the analysis of residual welding stresses and deformation based on the inherent strain distribution along the welded joint is introduced. Distribution of inherent strains and longitudinal residual stresses in medium thickness plate weldment is calculated and analyzed. A new method of calculating inherent strains and longitudinal residual stresses is proposed.

Short-Term Kinematics of the Adria Plate and Space-Time Distribution of Major Peri-Adriatic Earthquakes

Seismic activity is quite strong in the peri-Adriatic zones, whereas the internal part of the Adria plate is almost aseismic. This pattern suggests that Adria is a solid block that interacts with the surrounding belts, trying to move roughly northward. Each major earthquake in a peri-Adriatic zone triggers the acceleration of the decoupled Adria sector, which induces a perturbation of the stress/strain fields in the still blocked boundaries of the plate. Step by step, the displacement of Adria involves more and more northern zones to finally reach the northern front of the plate (eastern Southern Alps). This interpretation seems to be compatible with the time patterns of seismic activity in the main peri-Adriatic zones since 1600 A.D., which may suggest repeated northward migrations of seismic crises. Each supposed migrating sequence involves major earthquakes in most zones. The main features of the first 4 seismic sequences (1600-1930) are used to get insights into possible regularities in the progressive activations of the peri-Adriatic zones. This information and the main features of the ongoing migrating sequence (since 1931) are then used to tentatively recognize the peri-Adriatic zones where the occurrence of next major earthquakes may be most likely.

Variation of singularity of earthquake-size distribution with respect to tectonic regime

Frequency-size relation of earthquakes in a region can be approximated by the Gutenberg-Richter law(GR). This power-law model involves two parameters: a-value measuring seismic activity or earthquake productivity, and b-value describing the relation between frequencies of small and large earthquakes.The spatial and temporal variations of these two parameters, especially the b-value, have been substantially investigated. For example, it has been shown that b-value depends inversely on differential stress. The b-value has also been utilized as earthquake precursor in large earthquake prediction.However, the physical meaning and properties of b-value including its value range still remain as an open fundamental question. We explore the property of b-value from frequency-size GR model in a new form which relates average energy release and probability of large earthquakes. Based on this new form of GR relation the b-value can be related to the singularity index(1-2/3 b) of fractal energy-probability power-law model. This model as applied to the global database of earthquakes with size M ≥ 5 from 1964 to 2015 indicates a systematic increase of singularity from earthquakes occurring on mid-ocean ridges, to those in subduction zones and in collision zones.

Investigation on fracture models and ground pressure distribution of thick hard rock strata including weak interlayer

Dynamic disasters,such as rock burst due to the breaking of large area stiff roof strata,are known to occur in the hard rock strata of coal mines.In this paper,mechanical models of the fracturing processes of thick hard rock strata were established based on the thick plate theory and numerical simulations.The results demonstrated that,based on the fracture characteristics of the thick hard rock strata,four fracture models could be analyzed in detail,and the corresponding theoretical failure criteria were determined in detail.In addition,the influence of weak interlayer position on the fracture models and ground pressure of rock strata is deeply analyzed,and six numerical simulation schemes have been implemented.The results showed that the working face pressure caused by the independent movement of the lower layer is relatively low.The different fracture type of the thick hard rock strata had different demands on the working resistance of the hydraulic powered supports.The working resistance of the hydraulic powered supports required by the stratified movements was lower than that of the non-stratified movements.

Evolution of lithofacies and paleogeography and hydrocarbon distribution worldwide(Ⅱ)

Based on the compilation and analysis of the lithofacies and paleogeography distribution maps at present and paleoplate locations during six key geological periods of the Mesozoic and Cenozoic,the lithofacies and paleogeography features and their development laws were expounded.Based on our previous research results on lithofacies and paleogeography from Precambrian to Paleozoic,we systematically studied the features and evolution laws of global lithofacies and paleogeography from the Precambrian and their effects on the formation of source rocks,reservoirs,cap rocks and the distribution of oil and gas worldwide.The results show that since Precambrian,the distribution areas of uplift erosion and terrestrial clastic deposition tended to increase gradually,and increased significantly during the period of continental growth.The scale of coastal and shallow marine facies area had three distinct cycles,namely,from Precambrian to Devonian,from Carboniferous to Triassic,and from Jurassic to Neogene.Correspondingly,the development of shallow carbonate platform also showed three cycles;the lacustrine facies onshore was relatively developed in Mesozoic and Cenozoic;the sabkha was mainly developed in the Devonian,Permian and Triassic.The Cretaceous is the most important source rock layers in the world,followed by the Jurassic and Paleogene source rocks;the clastic reservoirs have more oil and gas than the carbonate reservoirs;the basins with shale caprocks have the widest distribution,the most abundant reserves of oil and gas,and the evaporite caprocks have the strongest sealing capacity,which can seal some huge oil and gas fields.

Evolution of lithofacies and paleogeography and hydrocarbon distribution worldwide(I)

By using a large amount of geological and geophysical data, the geological characteristics such as lithofacies and paleogeography of 4981 geological units at thirteen key geological periods or epoches since the Precambrian in the world have been figured out. The global lithofacies and paleogeography charts have been compiled by ArcGis mapping technology. Combined with the results of plate-paleogeography reconstruction, the lithofacies and paleogeography as well as the prototype basins of these global paleoplates have been restored with the Gplate software. Results show that there are 22 kinds of lithofacies combinations and 10 types of paleogeography units developed since Precambrian. These features of lithofacies and paleogeography as well as their evolution were mainly controlled by the divergent and convergent movements of those plates. Taking the results of the lithofacis and paleogeography at the present and paleoplate location during the seven key geological periods from the Precambrian to Paleozoic for example, during the Late Precambrian and Cambrian, the large-scale disintegration of the Rodinia supercontinent resulted in reduction of uplift denudation area and clastic terrestrial facies area, the expansion of coastal-shallow marine facies and shallow-water carbonate platform. In Devonian, uplift denudation area and clastic terrestrial facies area began to increase and littoral-shallow marine facies area and shallow-water carbonate platform shrank as a result of the formation of Larussia supercontinent. In the Permian, with the formation of the Pangea continent, the development of the global uplift denudation area and clastic terrestrial facies reached its peak, while the littoral and shallow marine facies were very limited in distribution. The lithofacies and paleogeography features and evolution patterns of different stages lay a solid foundation for analyzing the formation conditions of geological elements, such as source rocks, reservoirs and cap rocks for oil and gas accumulation, and revealing the distribution regularity of oil and gas around the world.

Logistic Regression for Prediction and Diagnosis of Bacterial Regrowth in Water Distribution System

This paper focuses on the quantitative expression of bacterial regrowth in water distribution system. Considering public health risks of bacterial regrowth,the experiment was performed on a distribution system of selected area.Physical,chemical,and microbiological parameters such as turbidity,temperature,residual chlorine and pH were measured over a three-month period and correlation analysis was carried out.Combined with principal components analysis(PCA) ,a logistic regression model is developed to predict and diagnose bacterial regrowth and locate the zones with high risks of microbiology in the distribution system.The model gives the probability of bacterial regrowth with the number of heterotrophic plate counts as the binary response variable and three new principal components variables as the explanatory variables.The veracity of the logistic regression model was 90%,which meets the precision requirement of the model.

Acoustic CT system for temperature distribution measurement

In this paper, a measurement method for cross-sectional temperature distribution is addressed. A novel method based on an acoustic CT technique is proposed. Specifically, the temperature distributions are estimated using the time of flight data of several ultrasonic propagation paths. The times of the flight data contain both temperature and wind effect, and the method to select only temperature component is introduced. A filtered back projection method is applied to reconstruct the temperature distributions from the time of flight data. An experimental system was designed and fabricated to realize simultaneous temperature and wind velocity distribution measurements. Through this system, the effectiveness of the proposed measurement method is confirmed.

开孔促淤板周围悬沙浓度分布特征数值分析

开孔促淤板作为保护岸滩的有效结构,一直被用于保滩护岸、河流海岸生态修复等工程。由于开孔促淤板的存在,使得其周围水流流态变得较为复杂,水流阻力增大,开孔促淤板周围的水流流态会直接影响板周悬沙的运动和输移。基于Mixture两相流模型,对不同开孔率的促淤板周围的流场特性以及悬沙浓度分布特征进行了数值模拟研究。结果表明:开孔促淤板后槽底近壁区(距底高度dH/15)区域,开孔处板后断面相对悬沙浓度值较板前大,格栅处的板后断面相对悬沙浓度较开孔处的板后断面相对较大。当来流流速一定时,开孔促淤板的开孔率越大,板周的相对悬沙浓度越低,开孔促淤板的促淤效果也越不理想;当开孔率为20%时,开孔促淤板的促淤效果显著。

Simulation of Droplet-gas Flow in the Effervescent Atomization Spray with an Impinging Plate

Abstract A comprehensive three-dimensional model of droplet-gas flow was presented to study the evolution of spray in the effervescent atomization spray with an impinging plate. For gas phase, the N-S equation with the κ-ε turbulence model was solved, considering two-way coupling interaction between droplets and gas phase. Dispersed droplet phase is modeled as Lagrangian entities, accounting for the physics of droplet generation from primary and secondary breakup, droplet collision and coalescence, droplet momentum and heat transfer. The mean size and sta- tistical distribution of atomized droplets at various nozzle-to-plate distances were calculated. Some simulation resuits were compared well with experimental data. The results show that the existence of the impinging plate has a pronounced influence on the droplet mean size, size distribution and the droplet spatial distribution. The air-to-liquid ratio has obvious effects on the droplet size and distribution.

Hydrodynamic Characteristics of Square Heaving Plates with Opening Under Forced Oscillation

The existence of the heaving plates can improve the heaving motion performance of an offshore structure significantly by providing both extra added mass and damping.In the current research,numerical investigation is carried out on the hydrodynamic characteristics of both isolated square heaving plate and double square heaving plates with opening by an immersed boundary-lattice Boltzmann method.The effects on hydrodynamic performance of plates due to Keulegan-Carpenter(KC)number,frequency number,opening ratio,opening distribution and spacing of plates are examined.It is found that the heaving plates with optimized opening ratio can provide additional damping compared with the plates without opening.Better hydrodynamic characteristics of double plates can be obtained with the increase of plate spacing.

Plate reinforced square hollow section X-joints subjected to in-plane moment

The static test of 13 square hollow section(SHS) X-joints with different β and different types of plate reinforcement under in-plane moment in brace was carried out. Experimental test schemes, failure modes of specimens, moment-vertical displacement curves, moment-deformation of the chord, and strain strength distribution curves were presented. The effect of β and plate reinforcement types on in-plane flexural property of SHS X-joints was studied. Results show that punching shear of chord face disappears, brace material fracture appears and concave and convex deformation of chord decrease when either collar plates or doubler plates were welded on chord face. Moment-vertical displacement curves of all specimens have obvious elastic, elastic-plastic and plastic stages. As β increases, the in-plane flexural ultimate capacity and initial stiffness of joints of the same plate reinforcement type increase, but ductility of joints decreases. With the same β, the in-plane flexural initial stiffness and ultimate capacity of doubler plate reinforced joints, collar plate reinforced joints, and unreinforced joints decrease progressively. Thickness of reinforcement plate has no obvious effect on in-plane flexural initial stiffness and ultimate capacity of joints. As thickness of reinforcement plate increases, the ductility of reinforced X-joints decreases. The concave and convex deformation of every specimen has good symmetry;as β increases, the yield and ultimate deformation of chord decrease.

Static and free vibration analysis of four-parameter continuous grading elliptical sandwich plates

In the present study,the static and dynamic analyses of elliptical functionally graded sandwich(FGS)plates are investigated.The constituent materials of the sandwich plates are ceramic and metal so that the core is made of pure metal,while the face sheets consist of a combination of metal and ceramic according to a four-parameter power-law distribution.Different material profiles such as classic,symmetric,and asymmetric can be obtained using the applied generalized power-law distribution relation.The analysis is performed based on the classical laminated plate theory(CLPT)and the Ritz method.The effects of four parameters in the material distribution relation as well as different geometric parameters on the deflection and natural frequencies of elliptical FGS plates are studied.The results of this study show that with a proper distribution of materials,the optimal static and dynamic behavior can be achieved.The results also indicate that the generalized power-law distribution has significant effects on the natural frequencies of elliptical FGS plates.For example,although the frequency parameter of a plate with ceramic face sheets is more than the one with metal face sheets,the use of larger amounts of ceramic does not necessarily increase the natural frequency of the structure.

A 2D numerical study on the condensation characteristics of three non-azeotropic binary hydrocarbon vapor mixtures on a vertical plate

To improve the transportation efficiency and reduce the supply cost,the liquefaction becomes an important technology to store and transport the natural gas.During the liquefaction,the various components(e.g.propane,ethane,methane etc.)undergo fractional condensation phenomenon due to their different boiling points.This means that when one component condenses,others play a role of non-condensable gas(NCG).In order to reveal the influence mechanism of NCG on this condensation process,a numerical method was employed in this paper to study the condensation characteristics of three non-azeotropic binary hydrocarbon vapor mixtures,namely the propane/methane(80%–95%),ethane/methane(65%–85%)and methane/nitrogen(2%–13%)mixtures,on a vertical plate.The model was proposed based on the diffusion layer model,and the finite volume method was used to solve the governing equations.A user defined function was developed by cell iterative method to obtain the source terms in the condensation process.The numerical results show that the gas phase boundary layer formed by the NCG becomes the main resistance to the reduction of heat transfer coefficient.And for the above three mixtures,there is a negative correlation between the NCG concentration and the heat transfer coefficient.Meanwhile,the results show a good agreement with the experimental data,meaning that the proposed model is reliable.Three mixtures within same non-condensable mole fraction of 20%were also investigated,indicating that the mixtures with a higher binary hydrocarbon molecular ratio have a lower heat transfer coefficient.As a result,the presence of the lighter NCG contributes to a thicker boundary layer.

Effect of porosity on active damping of geometrically nonlinear vibrations of a functionally graded magneto-electro-elastic plate

This paper investigates the effect of porosity on active damping of geometrically nonlinear vibrations(GNLV)of the magneto-electro-elastic(MEE)functionally graded(FG)plates incorporated with active treatment constricted layer damping(ATCLD)patches.The perpendicularly/slanted reinforced 1-3 piezoelectric composite(1-3 PZC)constricting layer.The constricted viscoelastic layer of the ATCLD is modeled in the time-domain using Golla-Hughes-Mc Tavish(GHM)technique.Different types of porosity distribution in the porous magneto-electro-elastic functionally graded PMEE-FG plate graded in the thickness direction.Considering the coupling effects among elasticity,electrical,and magnetic fields,a three-dimensional finite element(FE)model for the smart PMEE-FG plate is obtained by incorporating the theory of layer-wise shear deformation.The geometric nonlinearity adopts the von K arm an principle.The study presents the effects of a variant of a power-law index,porosity index,the material gradation,three types of porosity distribution,boundary conditions,and the piezoelectric fiber’s orientation angle on the control of GNLV of the PMEE-FG plates.The results reveal that the FG substrate layers’porosity significantly impacts the nonlinear behavior and damping performance of the PMEE-FG plates.

高含水油藏剩余油再分布规律研究——以江苏油田S区块为例

油田经过长期注水开发进入高含水阶段,产量下降较快以至停采,对停采的高含水油藏开展剩余油分布规律的再认识可以有效提高老油田采收率。为此开展了平板物理模拟实验,利用含油饱和度场分布对剩余油二次富集机理进行研究;同时结合数值模拟研究,验证了高部位区域剩余油分布规律,并对其主控影响因素进行分析。结果表明,剩余油受到残余阻力压差以及渗吸的作用,二次富集主要分布在注采连线的周边以及渗透率较低的高部位地区。确定了影响剩余油二次聚集的影响因素及技术界限值,即油藏满足停采时间超过36个月,地层倾角大于20°,平面渗透率级差大于2,渗透率大于50×10^(-3)μm^(2)等条件可开展油田高含水停采油藏二次挖潜。

TP304/Q235不锈钢复合钢板焊接组织性能研究

采用焊条电弧焊以及埋弧焊工艺对TP304/Q235复合钢板进行焊接试验,研究了焊接接头的显微组织、合金元素分布、力学性能和显微硬度。试验结果表明:复合钢板复层TP304焊缝和基层Q235焊缝的显微组织分别为奥氏体+铁素体(伴有魏氏组织)和铁素体+珠光体。复层TP304母材侧合金元素Cr、Ni的质量分数低于复层焊缝侧,随着距离复层母材位置的增加,Cr、Ni的质量分数表现出了缓慢上升的趋向,整体呈阶梯状分布。复合板接头抗拉强度处于TP304母材和Q235母材之间,且断裂位置为母材处。复层TP304侧焊接接头和基层Q235侧焊接接头的显微硬度分布趋势相似,表现为热影响区和焊缝金属的硬度值高于母材,且峰值都出现在热影响区内,分别为265 HV左右和440 HV左右。综上所述,在本次试验研究条件下,所得到的TP304/Q235复合钢板组织性能优越,保证了接头质量,为不锈钢复合钢板在化工生产和石油管道等领域的应用积累了经验。