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In the analysis of a complex structure subjected to an internal explosion event, a direct simulation using appropriate computational technique is very necessary. This paper presents material dynamic constitutive models including the strain rate effects for concrete and steel rebar , and introduces a numerical simulation study on the prediction of structure in the confined space using a hydrocode. A reinforced Concrete slab under internal explosion is analyzed using a proper coupled analysis scheme. The simulation results are compared with experimental observations. The favorable agreements are observed in the time histories of air overpressure and launching velocity of RC slab. It is found that the numerical simulation scheme incorporating an appropriate coupling at the solid-air interface proves to be capable of reproducing the shock reflection effect as well as the buildup of the gas pressure for explosion within the closed steel box, with adequate material models and suitable technique for fracture, the complicated cracking and break-up of RC components can be simulated in a rather realistic manner. The impulsive loading is responsible for the development of damage zone in the concrete and subsequent fragment size distribution, and the explosion gas loading is important in the launching velocity of RC slab. [ABSTRACT FROM AUTHOR]

In order to study the physical mechanism of explosion field in concrete, a code MMIC-3D is proposed based on the 3D Youngs' interface reconstruction algorithm. The formation and development process of the cavity and the law of bulge motion during the explosion in semi-infinite concrete are simulated. The three-dimensional numerical results of the explosion field in the semi-infinite concrete medium are obtained. The results showed that the computational data agree with the experimental phenomena and the physical law, which indicates that the algorithm and the hydrocode presented in this paper are correct, and can provide instruction for engineering designs. [ABSTRACT FROM AUTHOR]

This paper presents an effective stress-based numerical model for dynamic analysis of soil liquefaction considering the effect of confining pressure on of dynamic properties soil, which can be used to describe the pore pressure increment and the consequent loss of soil strength due to earthquake-induced shaking. The emendatory hyperbolic model which meets Masing rule is adopted for nonlinear analysis of soils in numerical model. The pore pressure generation is calculated using the equivalent cycle pore pressure model developed by Ishibashi and Sherif et al. To demonstrate the relability of the new method for dynamic soil liquefaction analysis, a two-dimensional numerical model is directly established to simulate shaking table test for seismic response of liquefiable ground, the parallel spring-damper connection is used to simulate the artificial boundary of computational domain and the Wilson-θ integral method is selected to solve dynamic equations of seismic response. The results obtained from the new analysis agree well with recorded accelerations and pore pressure ratio in the shaking table test, which shows the reliability and validity of the numerical mode [ABSTRACT FROM AUTHOR]

Based on a full degrees of freedom finite element model of gears, this paper presents a comprehensive approach to build a model of coupling geared rotors system. Gyroscopic effects and bearing support were considered in the model. Vibration property of geared rotor system can easily be analyzed by using this approach and effects of direction change of gear meshing line on dynamic meshing force is involved in the analysis. Forced response of a typical 2-stages geared system is investigated and good agreement between numerical simulation and experimental measurement was obtained. Mathematical model of a multi-stage pump was built according to previous approach and the results of numerical simulation show that coupling gears have obvious influences on vibration characteristics of the pump. These results are helpful for safe operation of the multi-stage pump. [ABSTRACT FROM AUTHOR]

This paper presents the results of numerical simulation for penetrating confined boron carbide with tungsten long-rod (L/D=20, L is the length, and D is the diameter of the tungsten long-rod) at impact velocity (v) from 1.5 to 5.0 km/s. Simulation is carried out with the AUTODYN code and its results are in good agreement upon the experimental test. The influences of arithmetic, size of net and erosion strain on computing results are investigated. The expressions of penetration velocity (u), consumption velocity (vc) and penetration depth (h) with impact velocity v are given in the end of the paper. [ABSTRACT FROM AUTHOR]

In this paper, means and method used for characterizing the interface behavior of single fiber composite are elaborated comprehensively from three aspects: mesoscopic-mechanical test, mesoscopic-mechanical models and numerical simulation. Mesoscopic-mechanical test establishes the basis for mesoscopic-mechanical models and numerical simulation. The relationship between them should be fully utilized to establish a sound system of interface performance characterization to accurately forecast the mechanical properties of composite materials and meet the requirements of various industries. [ABSTRACT FROM AUTHOR]

To solve the problem that the random optimization method costs huge calculation and the best response method tends to get a weak local optimization, an effective optimization algorithm is built in this paper, which use best expected improvement (EI) strategy to balance response value and response precision. Tests of airfoil shape optimization indicate that the drag coefficient is reduced by 22% and the calculation time is reduced by 68% comparing with that of the particle swarm optimization, which shows that this effective optimization algorithm is realizable and effective. [ABSTRACT FROM AUTHOR]

A computational study performed for an artillery projectile using finite volume TVD schemes is described in this paper. First, computed Magnus moment coefficients for the spinning projectile have been compared with the available experimental data of SOCBT at Mach 3 and are found to be generally in good agreement. The results demonstrate that the method can provide an accurate and viable approach for this problem. Then, computational fluid dynamics (CFD) modeling and analysis of the spinning projectile with fixed canard have been conducted to determine the longitudinal aerodynamic coefficients. The analyses provide a detailed understanding of the effects of canard with different circumferential position on longitudinal aerodynamic coefficients at three supersonic speeds and various angles of attack. [ABSTRACT FROM AUTHOR]

A numerical simulation method is proposed in this paper for system dynamic reliability analysis of stochastic structures under non-stationary seismic excitations. Structural dynamic equations are first transformed into the form of state equations and then solved by the precise time integral method, which yields the structural responses as the combination of a series of products of random coefficients and random excitations at each discrete instant. The random coefficients are the functions of structural random parameters, reflecting the influence of the structural random parameters on the random responses. Based on the time-domain method for analysis of non-stationary random responses of deterministic structures, the random co-efficients are fitted as quadratic functions of the structural random parameters without cross-terms, which leads to the explicit expressions of structural responses with regard to the structural random parameters and random excitations at each instant. By using the explicit expressions deduced, numerical simulation techniques can be readily employed to analyze the structural system dynamic reliability beyond the first excursion failure Criterion. The system dynamic reliability of a stochastic frame structure subjected to non-stationary seismic excitation is obtained by the proposed method and the traditional Monte-Carlo method. The calculation accuracy and efficiency of the proposed method are compared with those of the Monte-Carlo method, showing that the present approach has ideal accuracy and considerably high efficiency. [ABSTRACT FROM AUTHOR]

The natural gas supersonic separation technology is the new dehydration technology which is developed in recent years. The vortex generator and nozzle are two key components of the natural gas supersonic separator. Numerical simulation research was carried out on the flow fields of three types of vortex generators with straight blade, angled blade and curved blade. The results show that the vortex generator with curved blade has a good performance. In addition, the nozzle flow of the natural gas supersonic separation was studied, and the results proved that the vortex generator and nozzle mentioned in this paper can get lower temperature and more powerful centrifugal force, which will condense the water vapor in the natural gas into small droplets and then be separated out so as to achieve the goal of natural gas dehydration. [ABSTRACT FROM AUTHOR]

As the aerodynamic forces are inconvenient to be measured in the wind tunnel tests of rain-wind-induced vibration (RWIV) of a stay cable under artificial simulation of rainfall, this paper presents a hybrid approach combining experiment anti computational fluid dynamics (CFD) numerical simulation for RWIV of a stay cable. The stay cable (including the rivulet) and the flow field are considered as two substructures in the entire system, and the motions of stay cable and rivulet measured through wind tunnel tests are considered as known boundary condition and applied to the flow field. The flow around the moving boundary is then numerically simulated by the Fluent CFD code. First, the feasibility and precision of this approach are verified through the vortex-induced vibration of a circular cylinder, and then the approach is used to study the RWIV of the stay cable. The transient aerodynamic lift and drag coefficients are calculated and applied to a single degree of freedom model (SDOF) of the stay cable. The comparison is carried out between the oscillation responses of the SDOF model and experimental results, which indicate that the hybrid approach combining experiment and CFD numerical simulation can effectively simulate the transient aerodynamic coefficients of stay cable suffering from the RWIV. [ABSTRACT FROM AUTHOR]

To study the contamination distribution in a chamber with perforated ceiling air supply, simulative analysis and experimental tests are carried out in this paper. In modeling, the Basic model and N-spot air model are both used for defining the orifice entrance boundary condition. The simulation results show that the distribution of contamination concentration agrees well with the test result. Especially, the simulation result of the N -spot air model is closer to the experimental one, which proves the feasibility of this model in analyzing indoor contamination distribution. [ABSTRACT FROM AUTHOR]

Endothermic effects in desorption process of natural gas vehicle tank seriously affects the gas desorption efficiency and vehicle speed. In this paper, a numerical model in desorption process of heating natural gas vehicle tank by engine cooling water was established, and by which the desorption processes were calculated. It shows that when the tank is heated by the engine cooling water, the rising of temperature makes the desorption amount of natural gas increased obviously. Also, the increasing of diameter of internal cooling pipe and thermal conductivity of adsorbent can increase the desorption amount. [ABSTRACT FROM AUTHOR]

WAWS is the most common used method, and it can produce random data time series with good accuracy, but the low efficiency and memory exceed problem is inevitable at the case of large amount of variates and long time series. An improved method combining WAWS and proper orthogonal decomposition (POD) technique is used in this paper to improve the computational efficiency, which is obviously efficient in both time and memory consumption. Furthermore, an error standard is defined to estimate the simulation precision, which can be used for choosing the order of POD method and error prediction prior to the simulation process. Finally, an example for numerical simulation of 200 points in random wind field is given to demonstrate the accuracy and effectiveness of this method. [ABSTRACT FROM AUTHOR]

Well productivity prediction is the key point and important reference to oilfield development and artificial lift design. In order to establish a method and model of productivity prediction for the CO2 flooding well, considering the influence of formation pressure and drainable radius, permeability and relative permeability curves, crude oil components, CO2 concentration and skin factor over well productivity, this paper have designed the orthogonal test and a number of reservoir numerical simulation calculations. Then based on the method of Vogel to establish well productivity equation of dissolved gas-drive reservoir, the first model of well productivity prediction for CO2 flooding was established through translating the numerical simulation results into integrated dimensionless. Example applications have launched in 2 pilot wells in Jilin oilfield and the results showed that the average relative error of 11 data points is 4.27% while the maximal relative error is 9.07%. This indicated that the prediction precision of this method and model proposed in the paper is relatively high. So it has certain application value in preparing oilfield development plan and well lifting design of CO2 flooding. [ABSTRACT FROM AUTHOR]

Inflow Control Devices(ICD) represents a new well completion technology for controlling bottom water which provides uniformity of the inflow profile by restricting high specific inflow segments while increasing inflow from low productivity segments. This paper studys with numerical simulation the effects of the proportion of high permeability zone, permeability grading, the length of control section and the flow rate of control section on the water breakthrough performace of a reservoir with bottom water using ICD,and determines the optimum placement of inflow control device, the flow resistance rating and the length of control section. The results show that the smaller the proportion of high permeability zone is and the larger permeability grading is, the better the water breakthrough performace of a reservoir with bottom water is in heterogeneous reservoirs, and ICD mounting location, length and limit flow rate have an importantment of water breakthrough performace of a reservoir with bottom water. In order to make the water control and oil increment effect maximization, ICD should be installed in horizontal well section of high permeable zone, and the length must be equal to or slightly higher than the high permeable zone length. The flow rate in the high specific inflow segments shold be as close as possible to the average flow rate in all sections. [ABSTRACT FROM AUTHOR]

Finite diameters of seven-hole probes will bring systematic errors in the measurement in shearing flow. In this paper, the calibration of the coefficient matrix of the three-dimensional seven-hole probe in steady flow field is carried out by numerical simulation. It is studied that several factors, such as velocity gradient, probe diameter and roll angle, cause systematic error in the measurement of parallel shearing flow field by numerical simulation. In the experiment of seven-hole probe measurement of the shearing flow field, it is determined the spatial resolution of the seven-hole probe in shearing flow fields. "Critical diameter" is defined and the error distribution of seven-hole probes is established in this paper in the measurement of shearing flow fields under the allowance of error. [ABSTRACT FROM AUTHOR]

The paper presents a methodology for calculating the unsteady aerodynamic forces characteristics and gust response of the unmanned air vehicle (UAV) model using computational fluid dynamics (CFD) tools, and the efficiency of gust alleviation based on direct force control are also studied. Based on unsteady Euler equations, dynamic responses in vertical gust flow perturbation are investigated. The grid velocity method, which is used to model unsteady flow via grid movement, is introduced to simulate the gust influence. This approach avoids numerical instabilities and decouples the step change in the angle of attack from a pitch rate. And the dynamic chimera grid method is used to simulate the rudder movement of the gust alleviation effect. Numerical results for the NACA0006 airfoil are validated by comparison with analytical results for two dimensional indicial responses. The initial and final lift values of the indicial responses closely match the exact analytical values as given by piston theory and quasi steady thin airfoil theory respectively. The solutions at small times match quite closely the exact solution which is known only for small times given by linear theory. The application of the same method to the UAV model reveals important characteristics of the three-dimensional vertical discrete gust response for the One-minus-cosine gust profile and gusts cause step changes in the angle of attack, and important characteristics of the gust response and resulting flow features are explained. Furthermore, the flow perturbations under dynamic rudder motion are investigated using moving chimera grid technique. Our study shows that with certain designed motions, the flapping rudder can effectively alleviate the freestream gust fluctuation and ensure a stable flight. However, no single parameter can determine whether the flapping rudder can reduce the gust effect. Finally, unsteady aerodynamic loads are computed for the wing of model with the designed rudder motion, the significance of the gust propagation effects is shown. It is found that the direct calculation of the gust response using CFD gives quite accurate results and provides a rich database. In general, this paper shows that the well-designed rudder movement can effectively alleviate the freestream gust fluctuation and ensure high flight qualities. [ABSTRACT FROM AUTHOR]

Airfoils of larger thickness are needed to improve the rigidity of the inflatable wing, while their aerodynamic efficiency is generally not great. A new aerodynamic configuration of double row wings applied to low-speed aircraft is discussed in this paper, and based on this, a new configuration which adds proper installation angle to the posterior wing is discussed. Moreover, the effect of the relative location of the double wings as well as the airfoil thickness on the row double-wing configuration is also studied. Numerical simulation result indicates that high-pressure zone around stagnation point at the leading edge of the posterior wing increases the pressure under the anterior wing, which will improve the lift and lift-drag ratio of aircraft obviously at a range of small and middle angles of attack. At a 4° angle of attack, the lift-drag ratio is improved by an extent of 62.8%, while 2° installation angle to the posterior wing is able to further improves the lift-drag ratio of the wing-body by 70.5%. Meanwhile, aerodynamic performance of the double-wing configuration is sensitive to the relative location of the double wings. The thicker is the airfoil, the smaller is the camber, and the more efficient is the row wing configuration studied. The overall effect shows that the aerodynamic configuration researched provides a new approach to the design of inflatable aircrafts. [ABSTRACT FROM AUTHOR]

To verify the feasibility of the numerical methods and solution strategies for simulating the flows a round bluff bodies controlled by steady suction, the separation and reattachment over a suction-controlled backward-facing step (BFS) flow is numerically investigated using the dynamic kinetic energy subgrid-scale model (DKEM) model based on the large eddy simulation (LES) method and the SST k-ω model based on the Reynolds averaged Navier-Stokes (RANS) method, respectively. Comparisons of the mean pressure coefficient and reattachment length between the numerical simulations and the existed experiment are also conducted to prove the validity. The results indicate that the LES can acquire exact results under the refined grid adopted in the paper. Suction control with any suction flow coefficient CQ can reduce the recirculation zone and reattachment length, and thus improve the flow fields downstream the step. With the increasing increments of the absolute CQ, the effect of suction control is more significant. [ABSTRACT FROM AUTHOR]

Numerical model of hybrid contra-rotating propeller (CRP) podded propulsion is built in numerical cavitation tunnel, and the hydrodynamics performance of hybrid CRP podded propulsion in uniform flow is predicted by RANS formula with SST k-w turbulence model based on sliding mesh method. The predicted results of open-water performance and unsteady performance of hybrid CRP podded propulsion are analyzed. Synchronously, a series of experimental investigations for open-water performance of hybrid CRP podded propulsion are carried out. Pod dynamical instrument and long-axis dynamical instrument are used in cavitation tunnel of the same size. The repeated tests' results are compared well with each other, indicating that the tests are stable. The average value of the repeated tests' results agree well with the prediction results of open-water performance. It is shown that the experimental method and the numerical method presented in this paper have good precision in the prediction of hybrid CRP podded propulsion's open-water performance. The average value of the repeated tests' results and predicted results are compared with the foreign experimental value of the same CRP without pod. The influence of pod on the open-water performance of the forward propeller and the after one are analyzed. It is shown that pod has no influence basically on open-water performance of the forward propeller, but has an obvious influence on the after one. [ABSTRACT FROM AUTHOR]

CFD method has the advantage of well simulating the flow over wind farm of complex terrain, compared with the method of using the software WAsP with linear model, thus becoming the development direction of assessment of wind resources in complex terrain. In order to use the CFD package FINE/TURBO and standard k-ε turbulence model with wall function in the wind resources assessment and micrositing of wind farm in the complex terrain, in this paper, Island Nanao had been simulated in wind directions at intervals of 30 degrees, under the assumption of neutral condition, to investigate the influence of inlet condition on the results. The simulation results show that the wind speed-up and intensity don't change essentially under different inlet conditions. Based on this law, with whole year wind data, an assessment method with post processing has been built, providing a strong reference for engineering practice. [ABSTRACT FROM AUTHOR]

This paper is the numerical investigation reports about field characteristic of fan section. First, it presents the control equations and boundary conditions for numerical simulation. Then the details of numerical results are given about velocity characteristics of fan section in 0.55mX0.4m low turbulence aero- acoustics wind tunnel. Conclusion could be got that numerical methods used could give rational results comparing with experiment data. Then, basing on the flow around rotor and stator, the flow mechanism inside fan section was analyzed. At last different fan models were study based on the numerical results. These parameters imposed influence on performance and flow mechanism of fan including the distance between rotor and stator, stator swept and leaned. Stator leaned could significantly reduce or eliminate rotor wake and tip separation, and could produce a more uniform velocity profile at exit. Conclusions state the importance and feasibility of CFD in aerodynamical design of fan section in wind tunnel. [ABSTRACT FROM AUTHOR]

Wind tunnel tests of wind loads acting on the roof of Shenzhen new railway station were conducted in a boundary layer wind tunnel at Hunan University, for the conditions without train and with trains inside the station. In addition, the effects of wind speed amplify in the station were also investigated. This paper presents the results of the mean and RMS wind pressure coefficients, and comparisons of the maximum mean negative wind pressure coefficients and fluctuating wind pressure coefficients for the case of without train and with trains were made. Furthermore, the characteristics of probability density functions of wind pressures measured from typical pressure taps were analyzed, and the peak factors of that were estimated under a probability significance level of 99.999%. On the other hand, the results obtained from numerical simulations were also presented in the paper, and the results were compared with the wind tunnel test data. The outcomes of the combined experimental and numerical study indicate that: (1) The maximum mean negative wind pressure coefficients on the roof occur at the windward leading edge region, where the maximum fluctuating wind pressure coefficients occur also in this region; (2) There are some differences of the maximum mean negative wind pressure coefficients and RMS wind pressure coefficients under conditions with different number of trains inside the station, but such effects on the overall pressure distributions on the whole roof are negligible; (3) There are clearly negative skewed distributions for some pressure taps at the windward leading roof edge and much longer negative tails are observed, which follow Non-Gaussian distributions; (4) Wind flow was found to be congregated inside the holes at the structure, and the maximum wind speed amplify coefficient is up to 1.34; And (5) the results obtained from the numerical simulations are in good agreement with these of the wind tunnel test, illustrating that the Large Eddy Simulation (LES) approach and Discretizing and Synthesizing Random Flow Generation (DSRFG) technique are effective tools for numerical simulations of wind effects on the complex long-span roof structures. [ABSTRACT FROM AUTHOR]

The hydraulic fracturing treatment in oil well is a process of solid-fluid coupling in porous medium. In this paper, continuity equation of hydraulic fracturing fluid seepage and stress equilibrium equation of rock deformation are established, the criterion for fracture initiation of quadratic nominal stress and fracture propagation of critical energy release rate is introduced, horizontal flow and vertical flow of fluid along fracture is considered, and the Soil module in finite element tool ABAQUS is applied to stimulate 3D composite fracture initiation and propagation in hydraulic fracturing. The cohesive element is used to pre-define the fracture path, and the corresponding user subroutines are also developed and embedded into ABAQUS to determine the initial in-situ stress field, seepage field, depth-dependent porosity and time-related loss coefficient. The result of numerical simulation can show fracture geometry, fluid pressure distribution along fracture, rock deformation and stress distribution, pore pressure distribution and fluid loss at different time points of pumping in hydraulic fracturing. Apart from that, the influence of fluid properties, volume, interlayer stress difference and loss coefficient on fracture geometry is analyzed. [ABSTRACT FROM AUTHOR]

In order to design the piped hydraulic transportation technique of tube-contained raw material reasonably, mathematical model on the piped hydraulic transportation of tube-contained raw material was established based on the hydraulic characteristics of the piped hydraulic transportation of tube-contained raw material in the paper. The mathematical model was solved by FLOW-3D and simulated values were compared with the experimental values. The results find simulated values and experimental values of the pressure field and flow field on the piped hydraulic transportation of tube-contained raw material are in substantial agreement. These show the mathematical model is right and the solve is feasible by the software. These will provide theoretical reference for the technical application of the technique. [ABSTRACT FROM AUTHOR]

Vegetation is a component of the natural river. To understand the interaction between vegetation and water flow is of scientific and practical significance for the protection of wildlife habitats, the control of water body eutrophication, the ecological restoration of rivers and lakes, and the management of riverways. This paper reviewed the researches about the interaction between vegetation and water flow in riverways, summarized the research progress in the effects of the vegetation on the resistance coefficient and water flow structure, and introduced the applications of numerical simulation in this research field. Based on the previous studies, the effects of river section shape, plant individual form, and vegetation distribution pattern on the flow regime of water flow in vegetation section were analyzed. For further study, the importance of deeply understanding the hydraulics mechanisms of the interaction between vegetation and water flow in terms of the diversity of river morphology, the vegetation variation at different spatiotemporal scales, the water flow distribution in vegetation section, and the three dimensional turbulent simulation was expatiated. [ABSTRACT FROM AUTHOR]

For controlling the flow separation on the wing at high angle of attack, an innovative technique for a finites-span wing stall control, flow deflector, is studied in the present paper. Wind tunnel experiments are conducted to validate the reliability of the numerical simulation. The comparison between them indicates that the flow deflector can control the stall of a wing and restrain the flow separation effectively at high angle of attack. Deep research of flow direction changing trend and boundary layer are carried out to investigate the mechanism of flow deflector. The results indicate that the flow deflector increase the angle of flow around the leading edge of the wing and decrease the angle of the coming flow to make it deflect to the upside of the wing. The flow deflector can suppress the three dimensional effects and maintain the two dimensional flow characteristics to some extent. Furthermore, the flow deflector can easily change the velocity profile in the boundary layer and make it more "fuller". It decreases the shape factor and increases the stability of the boundary layer to restrain the flow separation. [ABSTRACT FROM AUTHOR]

A team of specimens containing different dip angles of a single three- Dimensional (3D) crack were made by using a new type of unsaturated transparent and rock-like resin. The propagation and coalescence process of a single 3D crack under uniaxial compression were studied, and its production conditions and mechanism were further analyEed. It's shown by the test results that the failure process of specimens containing a single 3D crack can be generally divided into four stages. The fracture of a single 3D crack, which produces a variety of different forms of cracks, is much more complex than the fracture of a single 2D crack. In this paper, by employing the analysis software of FLAC3D and establishing a new elastic-brittle constitutive relation, as well as using superfine unit division, the propagation process of a single 3D crack were simulated and studied. The numerical results match well with the testing results in this paper and that obtained by former scholars, which suggests the effectiveness of the new numerical simulation method. [ABSTRACT FROM AUTHOR]

In this paper, based on the fixed hypersonic inlet with rectangular section, a new concept of variable geometry hypersonic inlet that the tip can turn and move back off to increase the mass capture ratio is presented, and operating in a large Mach number range from 4 to 6.5. The flow in the hypersonic inlet was analyzed with numerical analyzer, and the inlet performance comparisons were made between the variable geometry hypersonic inlet and fixed inlet at different Mach number of inflow. The results indicated that the performance of the variable geometry inlet as much as fixed one under design Mach number, and the performance of the variable geometry inlet was better than fixed inlet under non design point. All of that indicate that the variable geometry hypersonic inlet was satisfying. [ABSTRACT FROM AUTHOR]

A method of designing icing detection system for wind turbine is presented in this paper. The main idea of the approach is to integrate icing sensors on an extra prober and to predict ice on wind turbine according to the prober icing. Basic steps for design are proposed. Numerical arithmetic used for design configuration and shape of the icing prober is given. The arithmetic is composed of the Multiple Reference Frame (MRF) method to calculate flowfield of air, a Lagrangian method to compute droplet trajectories and a technique for fast computing ice accretion. Icing prober configuration for a 1.5MW horizontal axis wind turbine is then obtained with the approach. The state of wind turbine icing can be indicated by the prober in real time. All these achievements build a good base for future research. [ABSTRACT FROM AUTHOR]

Orifice leaking of high-sulfur natural gas pipeline happened frequently due to corrosion and other reasons in operation process, which will cause harm to personal safety and environment. In this paper, the CFD software Fluent is used to simulate the diffusion of methane and hydrogen sulfide after orifice leaking of sour gas pipeline in windy conditions. The result shows hat because of the buoyant effect, methane diffusion trends to high altitude and its explosive anger is near the leaking hole. Hydrogen sulfide spreads to high altitude due to the large initial momentum near leaking hole, but with the decrease of momentum and the increase of diffusion distance, it gradually fall near to ground under the action of gravity. By comparison of methane and hydrogen sulfide diffusion under the condition of wind speed at 3 m/s and 1 m/s, the methane explosion range increase slightly at the wind speed of 1 m/s, high concentration hydrogen sulfide can achieve higher range, and the ground concentration close to leaking hole will be lower. [ABSTRACT FROM AUTHOR]

Large-span spatial structural systems have huge space volume and cover large open areas, thus in the event of unexpected loading the spatial structures may develop catastrophic progressive collapse, causing a large number of casualties and substantial losses. This raises the demand for studies on collapse of large-span space structures. Up until now, most of the published papers concerning about the progressive collapse focused on frame structures, for which reliable design methods and corresponding codes have thus been established. This paper gives an overall review on numerical analysis, experimental, as well as theoretical methods for the structural progressive collapse of large-span structures based on papers published in the literature and the authors" research work. A general discussion on the progressive collapse was first presented, followed by key techniques that may be adopted in numerical simulation, including the determination of discontinuous displacement field, impact-contact analysis, etc. Multi-scale computational methods and their implementation into collapse analysis were also included. Experimental studies on collapse of large-span structures were reviewed, with recommendations on key techniques including displacement measurement and initiation of failure. Collapse mechanism, evaluation of structure robustness and simplified assessment methods on large-span structures were also covered. [ABSTRACT FROM AUTHOR]

The investigation on the aerodynamic characteristics of a high speed ramjet propelled projectile with the design Mach number of 4 was performed by the method of numerical simulations. The internal and external drag acting on the projectile in passive flight phase was obtained through calculations. Variations of the drags were discussed at the range of Mach 4 to Mach 3. The results show that the inlet studied in current paper can restart at the design Mach number; the maximum total pressure recovery of the inlet is about 0. 25 at the sub-critical operational condition. When the passive flight Mach number decreases from 4 to 3, the internal drag coefficient changes scarcely, it is nearly 0. 06. While the external drag coefficient increases from 0. 16 at the Mach number of 4 to 0. 21 at the Mach number of 3. The total drag coefficient ranges from 0. 23 to 0. 27 while the Mach number decreases from 4 to 3. The scale of friction drag is about 40% in internal drag and 20% in external drag. [ABSTRACT FROM AUTHOR]

A laminar separation bubble appears generally on the Eppler387 airfoil at low Reynolds number. In the present paper, control of the laminar separation bubble over the Eppler387 airfoil at low Reynolds number using suction or blowing is investigated computationally employing the Fluent solver. Numerical simulations are carried out with a range varieties of the key control parameters of jet locations, jet angles and jet velocity ratios. Numerical simulations showed that employing the gamma-theta transition model coupling the SSTk-w turbulence model can predict the location and extent of the laminar separation bubbles accurately; blowing/suction control is effective in suppressing the laminar separation bubble over the airfoil and increasing the lift-to-drag radio at low Reynolds number obviously. The results with larger suction velocity ratios are better at the fixed suction jet locations while the smaller blowing velocity ratios results are better at the fixed blowing jet locations. Furthermore, suction on the airfoil's upper surface is more effective to control laminar separation bubbles than blowing control. [ABSTRACT FROM AUTHOR]

Cycloidal propeller is a new device composed of two or more blades, which can provide thrust in all directions. It has become a research hotspot in the field of aeronautics research in foreign countries recent years. In this paper, domestic and foreign progress of research on the aerodynamics performance of cycloidal propeller is summarized, which include theoretical analysis, numerical simulation and experiments. It is found that the precision of the current aerodynamic force computation models for cyclorotor are still not enough and cannot be used widely, thus there is need to develop a theoretical model which can consider the dynamic stall, induced drag and downwash effect; and there is little discussion about the mechanism of unsteady aerodynamics of cyclorotor. The numerical analysis method of cyclorotor is still developing and need to be combined with PIV experiments in future to explain the flow mechanism of the cyclorotor. The aerodynamics efficiency of cycloidal propeller is also been discussed, it is found that the conclusions of cycloidal propeller's aerodynamics efficiency in papers are not the same, but the recent experimental data has shown it can be higher than conventional lift device, such as rotor. Finally, some further research topics on the aerodynamics performance are proposed. [ABSTRACT FROM AUTHOR]

A finite element model combined with bridge deck pavement structural style is established to analyze mechanical properties and influence factors of bridge' deck pavement structure. The effect of different levels braking force coefficients, top and bottom layer material modulus combination of bridge deck pavement, deck pavement thickness variation are analyzed. Results show that different horizontal loads have little effect on principal stress but much effect on shear stress inside the pavement layer. With the increase of horizontal load, the maximum shear stresses inside pavement layer and waterproof adhesive layer increase linearly. Principal stress inside the pavement layer changes little, while shear stress between layers decreases in a small amplitude with the increase of combination modulus of pavement layer. Increase of the thickness of pavement layer has little effect on principal stress and maximum shear stress between layers decreases with increase of thickness. Conclusions obtained by this paper can be used to provide theoretical reference for material selection and structure design of bridge deck pavement. [ABSTRACT FROM AUTHOR]

The external factor plays an important role in affecting user's collective behaviors. However, the external factor from the viewpoint of theoretical model to analyze user's collective behaviors is missing. Thus this paper analyzed the structural property of user-object bipartite networks from a theoretical model. By taking into account the external factors and intrinsic attributes, with the help of generation function, it developed a theoretical model to derivate both the degree distributions of the user and object as well as their unipartite projections. Further, this paper gave an example and numerical simulations. The results show that the results of numerical simulation are consistent with the empirical ones very well, which suggests that it is feasible to analyze structural property of bipartite networks in terms of external factors and intrinsic attributes. [ABSTRACT FROM AUTHOR]

In order to design thermal protection system, it is important to predict heat transfer rate precisely on the hypersonic vehicles. In present paper, considering chemical reaction, interal energy excitation and thermo-chemical non-equilibrium effects of high temperature air, the thermo-chemical non-equilibrium flow-fields are simulated using the numerical code AEROPH_Flow. An aero physical numerical code system for Hypersonic vehicles, the distributions of heat transfer rate is obtained, and the analysis is done for the influence of the chemical reaction model, thermodynamic non-equilibrium model, surface temperature, surface material catalytic action on the computational results. The results show that thermo-chemical non-equilibrium models have a more important influence on the computational results, it is important for the selection of the correct air reaction model and thermal non equilibrium model according to the flight environment and thermo-chemical non-equilibrium mechanism of the flow field around the hypersonic vehicles; the heat transfer rate isn't always the highest for lower surface temperature, and it become very complicated for the variation law of heat transfer rate along with the surface temperature under the condition of high Mach number or thermo-chemical non-equilibrium flow, so the surface temperature may as well be fixed choosed according to the distribution of the real flight condition or different constant for computing exactly heat transfer rate on the hypersonic vehicles. [ABSTRACT FROM AUTHOR]

Computational fluid dynamics (CFD) gradually plays an important role in the evaluation of the wind tunnel design project. This paper is about the evaluation results of the slotted test section of 0.6m x 0.6m continuous transonic wind tunnel including alternative design and flow field quality, especially comparing full slot with half slot. It presents the control equations and boundary conditions for numerical simulation firstly. Then the details of numerical results about the high subsonic and low supersonic flow characteristic are given. The length of velocity uniformity region and velocity deflection angle meet the design accuracy and that proved the rationality. The half slot project was better than the full one at high subsonic. Low supersonic field could be achieved when air was bleed from plenum chamber. However, more bleed air rate, shorter length of velocity uniformity region. Full slot project had less disorder on flow of the plenum chamber than the half. Further investigation on the flow mechanism of re-entry flaps indicated that the flow was unsteady one significantly. [ABSTRACT FROM AUTHOR]

Summing up the theory analysis, simulation calculation and test study, this paper optimized the dual-mode warhead to achieve the conversion of jetting projectile charge (JPC) and jet (JET). It was analyzed the liner collapse situation under single point detonation and annular detonation by the theory, and optimized the shaped charge parameters, such as liner cone, radian radius, thickness and charge height, by the numerical simulation. Then, it obtained the initiation mode and the matching relations of the shaped charge parameters which could get the conversion between JPC and JET. The JPC was formed by single point detonation, and the JET was formed by annular detonation. The liner cone was chosen 80° ∼ 100° , the liner radian radius was 0. 1 time charge caliber, the liner thickness was designed in accordance with liner cone, and the charge height is 0. 9 time charge caliber. Aimed at the optimal structure, the X-ray imaging test was done, and the error between the test and simulation results is within 8%. [ABSTRACT FROM AUTHOR]

A numerical simulation is carried out for the analysis of Double--Inclined Streamline Ribs tube (DISR tube) which is used in vehicle exhaust heat recovery. The influence on the heat exchange performance by structural parameter is analyzed. The results shows that the DISR tube structural parameter exists the optimal value of rib length(l=38 mm), rib inclined degree (α = 45°), rib height(h = 2.5 mm) and rib pitch(P=60 mm). Comparing a DISR tube with a plain tube in the same condition and range of Reynolds numbers(Re=1.2x104~5 x 104), the Nusselt number is enhanced up to 54.5% ~90.7%, and the friction factor increases to 157.6%~204.2%. Meanwhile, when the field synergy angle was reduced from 90° to 80°, the heat transfer effect is enhanced significantly. The paper presents that the field synergy angle decline greatly near every ribs, which is the main reason for the heat transfer enhancement. [ABSTRACT FROM AUTHOR]

In this paper, nine single start tubes with different structural parameters were studied numerically based on Fluent. The velocity and temperature distributions in the tubes microcosmically revealed the mechanism of heat transfer enhancement. According to the result of numerical calculation, in the range of Re=10 000~45 000, the Nusselt number Nu of spirally fluted tube is 1.34 to 2.01 times that of the smooth tube, and resistance coefficient / is 2. 01 to 6. 40 times that of the smooth tube. Nu and f increase as e increases, and decrease as p increases. The comprehensive performance of the tube is obviously better than that of smooth tube. Number two tube which has the best comprehensive performance can increase heat flux by 14% ~ 19% in the condition of equal heat transfer area and pump power. [ABSTRACT FROM AUTHOR]

Waverider is considered to be an ideal configuration for hypersonic vehicles in the near-space, but due to the serious aero-heating and facture limitations, its infinite sharp leading edge should be blunted which would result in a remarkable loss of aerodynamic performance and have a great effect on the practical value of waverider configuration. In this paper, one blunt method is proposed based on the typical aero-heating characteristics of waverider. Furthermore, numerical technology is used to study the flow characteristics of blunt waverider, including the mechanism of bluntness impact and the feasibility of this new blunt method. An experiment has been done in FD-14A hypersonic shock wind tunnel to obtain the flow structure and heat flux distribution in the nose region of waverider model. The results show that bluntness induces a detached bow shock around the nose region and the phenomenon of spillage along the leading edge, which therefore results in an increment of drag and a reduction of lift and lift-to-drag ratio. However, the serious aero-heating is limited in the nose region for blunt waverider, smaller blunt radius can be used for most of the leading edge. Owing to the improvement of aerodynamic performance and negligible influence on thermal protection system, the blunt method proposed by the present paper is proved to be feasible for hypersonic waverider design. Under the studied conditions, the lift-to-drag ratio increases about 3.0%. If the blunt method is optimized, waverider configuration is still one of the most important candidates for hypersonic flight in the near-space. [ABSTRACT FROM AUTHOR]

The flow field and infrared radiation characteristics of three-nozzle for the rocket motor are numerically investigated. The interaction of three jets ejected from three-nozzle is analyzed and the flow field is obtained. When the jets are ejected from nozzle exits under the condition that the jet pressure is higher than the back pressure, the inflation of jets happens and the jet boundary contracts inward, thus producing the compression wave to suppress the over-expansion due to the reduction of pressure. Then compression wave expands and enhances for shock. And the expansion and compression wave zone size decreases, as well as intensity weakens along streamwise direction. Once the distance from the nozzle exit reaches 26 times of nozzle diameter, the three jets are merged together to form a jet. The plume infrared radiation distribution of the three-nozzle is similar to that of the single nozzle. It is evident that the total infrared radiation distribution in horizontal plane is different significantly from that in the vertical plane for the three-nozzle. [ABSTRACT FROM AUTHOR]