scholarly journals Numerical Analysis of the Aerodynamic Characteristics of the Open Line Intersection of Fast Freight Train with the Speed of 160 km/h

2021 ◽  
Vol 2125 (1) ◽  
pp. 012014
Author(s):  
Yue Zhang ◽  
Dongping Wang
Keyword(s):  
Pressure Wave ◽  
High Speed ◽  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
Pressure Amplitude ◽  
Freight Train ◽  
Measuring Point ◽  
Open Line ◽  
Volume Method ◽  
The Impact

Abstract With the increase of the speed of fast freight train, the aerodynamic effect of freight train in open-line intersection is more obvious. However, at present, there are many domestic researches on the aerodynamic characteristics of high-speed train open-line intersection, and almost no researches on fast freight train. Therefore, it is of great significance to study the aerodynamic characteristics of open line intersection of fast freight train in order to improve the safe operation of freight train in China. Based on the theory of computational fluid dynamics and finite volume method, uses FLUENT software to numerically calculate the three-dimensional, unsteady, compressible and turbulent flow fields in open line intersection of fast freight train at different speeds. The calculations results indicate that: when two freight trains meet, the amplitude of the pressure wave at the intersection side is the largest and the closer to the train bottom, the greater the amplitude of the pressure wave. The pressure amplitude of the bottom measuring point is 34.09% higher than that of the top measuring point. When two cars intersect at the same speed, the higher the speed, the greater the pressure amplitude and the pressure amplitude is proportional to the square of the speed. The fitting formula is: ΔP = cV2 ; When two trains intersect at different speeds, the impact on freight train with lower speed is greater than higher one.

Influence of Vented Tunnel Hood on Aerodynamic Characteristics

2012 ◽  
Vol 256-259 ◽  
pp. 1340-1343
Author(s):  
Ya Guang Yan
Keyword(s):  
Pressure Gradient ◽  
Compression Wave ◽  
High Speed ◽  
Three Dimensional ◽  
Pressure Change ◽  
Aerodynamic Characteristics ◽  
Simulation Calculation ◽  
Aerodynamic Effect ◽  
Volume Method ◽  
Better Than

On the basis of the three-dimensional ,unsteady-state , viscous N-S Equation and k-ε two equation turbulence model , the simulation calculation is made with the finite volume method on the aerodynamic effect of a high-speed train passing a tunnel.The numerical computation simulates the pressure change in the tunnel,analysises regularity of the the initial compression wave and the pressure gradient wave,compares the mitigation effect of the two hoods on the pressure gradient.The following conclusions have been drawn from the research: The amplitude of the initial compression wave is not significantly reduced with hood,however,the amplitude of the pressure gradient is significantly reduced with hood.And the mitigation effect of the vented hood is better than the unvented one.

Aerodynamic Characteristics Analysis of High-Speed Train on Cutting under Crosswinds

2013 ◽  
Vol 300-301 ◽  
pp. 62-67
Author(s):  
Kun Ye ◽  
Ren Xian Li
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
High Speed Train ◽  
Aerodynamic Forces ◽  
Cutting Depth ◽  
Cutting Slope ◽  
Characteristics Analysis ◽  
Relationship Of ◽  
The Relationship

Cutting is an effective device to reduce crosswind loads acting on trains. The cutting depth, width and gradient of slope are important factors for design and construction of cutting. Based on numerical analysis methods of three-dimensional viscous incompressible aerodynamics equations, aerodynamic side forces and yawing moments acting on the high-speed train, with different depths and widths of cutting，are calculated and analyzed under crosswinds，meanwhile the relationship of the gradient of cutting slope and transverse aerodynamic forces acting on trains are also studied. Simulation results show that aerodynamic side forces and yawing moments acting on the train（the first, middle and rear train）decrease with the increase of cutting depth. The relationship between transverse forces (moments) coefficients acting on the three sections and the cutting depth basically is the three cubed relation. The bigger is cutting width，the worse is running stability of train. The relationship between yawing moments coefficients acting each body of the train and the cutting width approximately is the three cubed relation. The transverse Aerodynamic forces decreased gradually with the increase of the gradient of cutting slope, the relationship between yawing moments coefficients acting each body of the train and the gradient of cutting slope basically is the four cubed relation.

The effect analysis of an engine jet on an aircraft blast deflector

2018 ◽  
Vol 41 (4) ◽  
pp. 990-1001
Author(s):  
Song Ma ◽  
Jianguo Tan ◽  
Xiankai Li ◽  
Jiang Hao
Keyword(s):  
High Temperature ◽  
Flow Field ◽  
High Speed ◽  
Deflection Angle ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Aircraft Engine ◽  
Experimental Results ◽  
Exhaust Gases ◽  
The Impact

This paper establishes a novel mathematical model for computing the plume flow field of a carrier-based aircraft engine. Its objective is to study the impact of jet exhaust gases with high temperature, high speed and high pressure on the jet blast deflector. The working condition of the nozzle of a fully powered on engine is first determined. The flow field of the exhaust jet is then numerically simulated at different deflection angle using the three-dimensional Reynolds averaged Navier–Stokes equations and the standard [Formula: see text]-[Formula: see text] turbulence method. Moreover, infra-red temperature tests are further carried out to test the temperature field when the jet blast deflector is at the [Formula: see text] deflection angle. The comparison between the simulation results and the experimental results show that the proposed computation model can perfectly describe the system. There is only 8–10% variation between them. A good verification is achieved. Moreover, the experimental results show that the jet blast deflector plays an outstanding role in driving the high-temperature exhaust gases. It is found that [Formula: see text] may be the best deflection angle to protect the deck and the surrounding equipment effectively. These data results provide a valuable basis for the design and layout optimization of the jet blast deflector and deck.

scholarly journals Compacting nanopowder materials by a pulse pressure generated by expanding plasma channel of a spark ignited by wire electrical explosion

2021 ◽  
Vol 24 (6) ◽  
pp. 1297-1310
Author(s):  
L. M. Chebotnyagin ◽  
V. V. Potapov ◽  
N. A. Ivanov ◽  
N. N. Ivanchik
Keyword(s):  
Powder Material ◽  
Pulse Pressure ◽  
Pressure Wave ◽  
High Speed ◽  
Pressure Pulse ◽  
Plasma Channel ◽  
Experimental Studies ◽  
Electric Explosion ◽  
Pressure Amplitude ◽  
Metal Pipes

The purpose of the article is to explore the possibilities of powder material compaction by the pressure pulse of an electric explosion of a conductor, establish a functional relationship between the parameters of the pressure pulse and an electrical technological installation for powder material compaction, select the parameters for pulse pressure amplitude and duration adjustment, and specify the design options of the working tool for powder material compaction. Analytical studies have been carried out on the basis of the method of formalized representation of the development of the process of pulse pressure wave formation and propagation where the latter is created by an expanding plasma channel of an electric spark in a transmitting medium initiated by an electric explosion of a wire. The simulation of high-speed de formation of the pipe wall under the action of the pulse pressure is carried out in the MATLAB software package. A scanning electron microscope is used to study the microstructure of the breakage of the compacted material with nanomodifiers. Based on the experimental studies on powder material compaction by the pulse pressure created by the expanding plasma channel of a spark initiated by an electric explosion of a wire when the current pulse f rom an electrotechnological installation is supplied to it, it has been determined that the magnitude and shape of the pressure pulse are most influenced by the parameters of this installation. Based on the obtained model studies, the optimal modes for compaction of nanomodified powders have been selected. The relationship is obtained between the parameters of the pulse pressure (Pm amplitude and pressure wave propagation form) and the electrotechnological installation (voltage, inductance, capacitance). It is proposed to use an acoustic-electric wave model to estimate the pressure that provides high-speed deformation of metal pipes, and to plot a deformation profile of metal pipes used for compaction. Analysis of SEM images of the fractures obtained in compact experiments has showed a high degree of particle compaction with the formation of a solid composite.

scholarly journals Impacts of a railway tunnel on the streams baseflow verified by means of numerical modelling

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Leonardo Piccinini ◽  
Valentina Vincenzi
Keyword(s):  
Numerical Modelling ◽  
High Speed ◽  
Three Dimensional ◽  
Tracer Tests ◽  
Maximum Flow ◽  
Mitigation Strategies ◽  
Railway Tunnel ◽  
Flow Measurements ◽  
Railway Line ◽  
The Impact

The high-speed railway line between Bologna and Florence (Italy) is mostly developed underground through the Tuscan-Emilian Apennine, and the tunnels severely impacted groundwater and surface water. The 15-km-long Firenzuola tunnel crosses siliciclastic turbidites: during drilling, water inrushes occurred at fault and fracture zones, and the tunnel continues to drain the aquifer. The water table dropped below the level of the valleys, and gaining streams transformed into losing streams or ran completely dry, as did many springs. Hydrological observations and two multitracer tests have previously characterized the stream-tunnel connections and the impact processes. In the framework of planning mitigation strategies to minimize impacts on stream baseflow, three-dimensional numerical modelling with MODFLOW (the EPM approach) is applied to evaluate the artificial minimum flow needed to maintain flow continuity along the stream during the recession phase. The establishment of the two presented models is based on hydrogeological monitoring data and the results of flow measurements and tracer tests. Maximum flow rates subtracted from stream baseflow by the tunnel along the connection structures are calculated for two streams with major impacts.

A modified Fresnel-based algorithm for 3D microwave imaging of metal objects

2018 ◽  
Vol 11 (4) ◽  
pp. 313-325
Author(s):  
Farshad Zamiri ◽  
Abdolreza Nabavi
Keyword(s):  
High Speed ◽  
Fourier Transforms ◽  
Low Cost ◽  
Three Dimensional ◽  
Computation Time ◽  
Microwave Imaging ◽  
Reconstruction Algorithms ◽  
Clock Frequency ◽  
Pipeline Architecture ◽  
The Impact

AbstractMicrowave holography technique reconstructs a target image using recorded amplitudes and phases of the signals reflected from the target with Fast Fourier Transform (FFT)-based algorithms. The reconstruction algorithms have two or more steps of two- and three-dimensional Fourier transforms, which have a high computational load. In this paper, by neglecting the impact of target depth on image reconstruction, an efficient Fresnel-based algorithm is proposed, involving only one-step FFT for both single- and multi-frequency microwave imaging. Numerous tests have been performed to show the effectiveness of the proposed algorithm including planar and non-planar targets, using the raw data gathered by means of a scanner operating in X-band. Finally, a low-cost and high-speed hardware architecture based on fixed-point arithmetic is introduced which reconstructs the planar targets. This pipeline architecture was tested on field programmable gate arrays operating at 200 MHz clock frequency, which illustrates more than 30 times improvement in computation time compared with a computer.

Lumped Capacitance and 3D CFD Conjugate Heat Transfer Modelling of an Automotive Turbocharger

2015 ◽  
Author(s):  
R. Burke ◽  
C. Copeland ◽  
T. Duda ◽  
M. A. Reyes-Belmonte
Keyword(s):  
Heat Transfer ◽  
High Speed ◽  
Weak Link ◽  
Three Dimensional ◽  
Sensitivity Study ◽  
Heat Fluxes ◽  
Strategy Development ◽  
Inlet Temperature ◽  
Compression Process ◽  
The Impact

One dimensional wave-action engine models have become an essential tool within engine development including stages of component selection, understanding system interactions and control strategy development. Simple turbocharger models are seen as a weak link in the accuracy of these simulation tools and advanced models have been proposed to account for phenomena including heat transfer. In order to run within a full engine code, these models are necessarily simple in structure yet are required to describe a highly complex 3D problem. This paper aims to assess the validity of one of the key assumptions in simple heat transfer models, namely, that the heat transfer between the compressor casing and intake air occurs only after the compression process. Initially a sensitivity study was conducted on a simple lumped capacity thermal model of a turbocharger. A new partition parameter was introduced αA, which divides the internal wetted area of the compressor housing into pre and post compression. The sensitivity of heat fluxes to αA was quantified with respect to the sensitivity to turbine inlet temperature (TIT). At low speeds, the TIT was the dominant effect on compressor efficiency whereas at high speed αA had a similar influence to TIT. However, modelling of the conduction within the compressor housing using an additional thermal resistance caused changes in heat flows of less than 10%. Three dimensional CFD analysis was undertaken using a number of cases approximating different values of αA. It was seen that when considering a case similar to αA=0, meaning that heat transfer on the compressor side is considered to occur only after the compression process, significant temperature could build up in the impeller area of the compressor housing, indicating the importance of the pre-compression heat path. The 3D simulation was used to estimate a realistic value for αA which was suggested to be between 0.15 and 0.3. Using a value of this magnitude in the lumped capacitance model showed that at low speed there would be less than 1% point effect on apparent efficiency which would be negligible compared to the 8% point seen as a result of TIT. In contrast, at high speeds, the impact of αA was similar to that of TIT, both leading to approximately 1% point apparent efficiency error.

scholarly journals Evaluation of the Potential Electromagnetic Interference in Vertically Stacked 3D Integrated Circuits

2020 ◽  
Vol 10 (3) ◽  
pp. 748
Author(s):  
Dipesh Kapoor ◽  
Cher Ming Tan ◽  
Vivek Sangwan
Keyword(s):  
Integrated Circuits ◽  
Integrated Circuit ◽  
Electromagnetic Interference ◽  
High Speed ◽  
High Performance ◽  
Near Field ◽  
Three Dimensional ◽  
3D Ic ◽  
Three Dimensional Integrated Circuit ◽  
The Impact

Advancements in the functionalities and operating frequencies of integrated circuits (IC) have led to the necessity of measuring their electromagnetic Interference (EMI). Three-dimensional integrated circuit (3D-IC) represents the current advancements for multi-functionalities, high speed, high performance, and low-power IC technology. While the thermal challenges of 3D-IC have been studied extensively, the influence of EMI among the stacked dies has not been investigated. With the decreasing spacing between the stacked dies, this EMI can become more severe. This work demonstrates the potential of EMI within a 3D-IC numerically, and determines the minimum distance between stack dies to reduce the impact of EMI from one another before they are fabricated. The limitations of using near field measurement for the EMI study in stacked dies 3D-IC are also illustrated.

scholarly journals The impact of pelvic lateral rotation on hindlimb kinematics and stride length in the red-legged running frog, Kassina maculata

2019 ◽  
Vol 6 (5) ◽  
pp. 190060 ◽  
Author(s):  
Amber J. Collings ◽  
Laura B. Porro ◽  
Cameron Hill ◽  
Christopher T. Richards
Keyword(s):  
High Speed ◽  
Stride Length ◽  
Reference Frames ◽  
Comparative Anatomy ◽  
Three Dimensional ◽  
Video Data ◽  
The Body ◽  
Kinematic Models ◽  
Lateral Rotation ◽  
The Impact

Some frog species, such as Kassina maculata (red-legged running frog), use an asynchronous walking/running gait as their primary locomotor mode. Prior comparative anatomy work has suggested that lateral rotation of the pelvis improves walking performance by increasing hindlimb stride length; however, this hypothesis has never been tested. Using non-invasive methods, experimental high-speed video data collected from eight animals were used to create two three-dimensional kinematic models. These models, each fixed to alternative local anatomical reference frames, were used to investigate the hypothesis that lateral rotation of the mobile ilio-sacral joint in the anuran pelvis plays a propulsive role in walking locomotion by increasing hindlimb stride length. All frogs used a walking gait (duty factor greater than 0.5) despite travelling over a range of speeds (0.04–0.23 m s −1 ). The hindlimb joint motions throughout a single stride were temporally synchronized with lateral rotation of the pelvis. The pelvis itself, on average, underwent an angular excursion of 12.71° (±4.39°) with respect to the body midline during lateral rotation. However, comparison between our two kinematic models demonstrated that lateral rotation of the pelvis only increases the cranio-caudal excursion of the hindlimb modestly. Thus, we propose that pelvic lateral rotation is not a stride length augmenting mechanism in K. maculata .

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