scholarly journals Study on Heat Exchange of Different Ventilation Structures of Asynchronous Traction Motor for High Speed EMU

2019 ◽  
Vol 5 (2) ◽  
pp. 16-30
Author(s):  
Weili Li ◽  
Junci Cao ◽  
Dong Li ◽  
Zhigang Wu
Keyword(s):  
Temperature Distribution ◽  
Wind Speed ◽  
High Speed ◽  
Heat Dissipation ◽  
Windward Side ◽  
Maximum Temperature ◽  
Leeward Side ◽  
Stator Core ◽  
Traction Motor ◽  
Asynchronous Traction Motor

Background: Aiming at the problems of high local temperature and uneven temperature distribution in asynchronous traction motor of high-speed Electric Multiple Unit (EMU) when it is running. Aim: In this paper, the influence of ventilation system with different structure on temperature distribution is studied. Methods: Taking 600kW asynchronous traction motor as an example, the electromagnetic-fluid-temperature analysis model of the traction motor is established, and the temperature values of different positions in the motor are obtained. The accuracy of the calculation results is verified by comparing with the actual measurement. On this basis, by adjusting the structure of stator and rotor axial ventilation holes, the relationship between temperature distribution and fluid flow state in motor is studied. In addition, the influence of fluid incidence angle on fluid velocity and heat dissipation performance of motor is also studied, and the ventilation structure scheme with relative balance of axial and circumferential temperature in motor is found out, which provides a reference strategy for the design of temperature rise of motor with forced ventilation structure. Results: The wind speed near the intake side of stator teeth and rotor teeth groove is less than that far from the intake side. The flow distribution trend of rotor vent is similar to that of stator vent, but the air in the groove is affected by centrifugal force of rotor rotation, which makes the wind speed difference on the intake side larger than that on the outlet side. The stator winding and rotor guide bar are affected by wind temperature to reach the maximum temperature at the end of the outlet respectively. The stator core is higher at the windward side and the leeward side than the other parts of the motor. The heat dissipation effect at both ends is good. The highest temperature of the stator core appears near the leeward side.

scholarly journals 2.5D Flexible Wind Sensor Using Differential Plate Capacitors

Sensors ◽  
2021 ◽  
Vol 21 (9) ◽  
pp. 3101
Author(s):  
Yu Wan ◽  
Zhenxiang Yi
Keyword(s):  
Wind Speed ◽  
Wind Direction ◽  
Parallel Plate ◽  
Electrode Array ◽  
Copper Electrode ◽  
Windward Side ◽  
Leeward Side ◽  
Electrode Layer ◽  
Young’S Moduli ◽  
Speed Up

In this paper, a novel 2.5-dimensional (2.5D) flexible wind sensor is proposed based on four differential plate capacitors. This design consists of a windward pillar, two electrode layers, and a support layer, which are all made of polydimethylsiloxane (PDMS) with different Young’s moduli. A 2 mm × 2 mm copper electrode array is located on each electrode layer, forming four parallel plate capacitors as the sensitive elements. The wind in the xy-plane tilts the windward pillar, decreasing two capacitances on the windward side and increasing two capacitances on the leeward side. The wind in the z-axis depresses the windward pillar, resulting in an increase of all four capacitances. Experiments demonstrate that this sensor can measure the wind speed up to 23.9 m/s and the wind direction over the full 360° range of the xy-plane. The sensitivities of wind speed are close to 4 fF·m−1·s and 3 fF·m−1·s in the xy-plane and z-axis, respectively.

scholarly journals Numerical Assessment on Rotation Effect of the Stagnation Surface on Nanoparticle Deposition in Flame Synthesis

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1361
Author(s):  
Lilin Hu ◽  
Zhu Miao ◽  
Yang Zhang ◽  
Hai Zhang ◽  
Hairui Yang
Keyword(s):  
High Speed ◽  
Deposition Time ◽  
Windward Side ◽  
Leeward Side ◽  
Rotation Effect ◽  
Nanoparticle Deposition ◽  
Numerical Assessment ◽  
O2 Concentration ◽  
Rotating Surface ◽  
Cfd Method

The effect of rotation of the stagnation surface on the nanoparticle deposition in the flame stabilizing on a rotating surface (FSRS) configuration was numerically assessed using CFD method. The deposition properties including particle trajectories, deposition time, temperature and surrounding O2 concentration between the flame and stagnation surface were examined. The results revealed that although flame position is insensitive to the surface rotation, the temperature and velocity fields are remarkably affected, and the deposition properties become asymmetric along the burner centerline when the surface rotates at a fast speed (rotational speed ω ≥ 300 rpm). Particles moving on the windward side have similar deposition properties when the surface rotates slowly, but the off-center particles on the leeward side have remarkable longer deposition time, lower deposition temperature, and lower surrounding O2 concentration, and they even never deposit on the surface when the surface rotates at a high speed. The rotation effect of the stagnation surface can be quantitatively described by an analogous Karlovitz number (Ka’), which is defined as the ratio of characteristic residence time of moving surface to the aerodynamics time induced by flame stretch. For high quality semiconducting metal oxide (SMO) films, it is suggested that Ka’ ≥ 1 should be kept.

scholarly journals Effect of windbreaks on wind speed reduction and soil protection against wind erosion

2017 ◽  
Vol 12 (No. 2) ◽  
pp. 128-135 ◽  
Author(s):  
D. Řeháček ◽  
T. Khel ◽  
J. Kučera ◽  
J. Vopravil ◽  
M. Petera
Keyword(s):  
Wind Speed ◽  
Wind Erosion ◽  
Statistical Significance ◽  
Polynomial Equation ◽  
Windward Side ◽  
Leeward Side ◽  
Soil Protection ◽  
Speed Reduction ◽  
Optical Porosity ◽  
Cultivated Plant

Windbreaks form efficient soil protection against wind erosion particularly at the time when soil cover is not protected by the cultivated plant vegetation cover. The objective of this research was to evaluate windbreaks efficiency in terms of wind speed reduction. Wind speed along the windbreaks was measured in the cadastral areas of Dobrovíz and Středokluky (Czech Republic, Central Europe). The measurement was carried out by 4 stations placed at windward side (1 station at the distance of 3 times the height of the windbreak) and at leeward side of the windbreak (3 stations at the distance of 3, 6, and 9 times the height of the windbreak). Each station contained 2 anemometers situated 0.5 and 1 m above surface. The character of windbreak was described by terrestrial photogrammetry method as the value of optical porosity from the photo documentation of the windbreak at the time of field measurement. A significant dependence between the value of optical porosity and efficiency of windbreak emerged from the results. The correlation coefficient between optical porosity and wind speed reduction was in the range of 0.842 to 0.936 (statistical significance more than 95%). A significant effect of windbreak on airflow reduction was proven on the leeward side of windbreak in a belt corresponding to approximately six times the height of the windbreaks depending on the optical porosity and it was expressed by a polynomial equation.  

scholarly journals Development and application of a street-level meteorology and pollutant tracking system (S-TRACK)

2021 ◽  
Author(s):  
Huan Zhang ◽  
Sunling Gong ◽  
Lei Zhang ◽  
Jianjun He ◽  
Yaqiang Wang ◽  
...  
Keyword(s):  
Air Pollution ◽  
Wind Speed ◽  
Line Source ◽  
Living Environment ◽  
Windward Side ◽  
Leeward Side ◽  
Street Level ◽  
Building Layout ◽  
Potential Impact ◽  
Traffic Source

Abstract. A multi-model simulation system for street level circulation and pollutant tracking (S-TRACK) has been developed by integrating the Weather Research and Forecasting (WRF), the Computational Fluid Dynamics (CFD) and the Flexible Particle (FLEXPART) models. The winter wind environmental characteristics and the potential impact of a traffic source on nearby sites (about 300 to 400 m) in Jinshui district of Zhengzhou, China are analyzed with the system. It is found that the existence of buildings complicates the structure of the wind fields. The wind speed inside the building block is smaller than the background wind speed due to the dragging effect of dense buildings. Ventilation is better when the dominant airflow is in the same direction as the building layout. Influenced by the building layout, local circulations show that the windward side of the building is mostly the divergence zone and the leeward side is mostly the convergence zone, which is more obvious for high buildings and influencing air pollution transport at the street-level. Using the traffic source (line source) on a road within a city block, the system was applied to investigate the potential impact of a line source on specific sites under the influence of the streel-level circulations. The potential contribution ratio was estimated by the method of residence time analysis and to a particular site found to vary with the height of the site with a peak not at the ground but on a certain height. The results of the study are helpful to understand the characteristics of wind environment and effect of traffic emissions in the area, which is important to improve urban living environment and control air pollution.

Hydrodynamic Effects of Bilge Keels on the Hull Flow During Steady Turns

2009 ◽  
Author(s):  
Charles M. Dai ◽  
Ronald W. Miller ◽  
A. Scott Percival
Keyword(s):  
High Speed ◽  
Great Influence ◽  
Cross Flow ◽  
Vortical Flow ◽  
Windward Side ◽  
Leeward Side ◽  
Ship Wake ◽  
Flow Component ◽  
Wake Field ◽  
Bilge Keel

The hydrodynamic design of the bilge keels is important for the ship’s resistance and roll performance. It also affects the ship wake field at the propeller plane and can greatly influence the propulsor performances in terms of noise, efficiency and cavitation. The objective of this work is to investigate the effect of bilge keels on the hull flow during steady turns for a displacement ship with a skeg and a bow dome. An Unsteady Reynolds Averaged Navier Stokes Solver (URANS) CFDShip-Iowa, Version 4, developed at the University of Iowa is used to simulate the flow around the Naval Surface Warfare Center-Carderock Division (NSWCCD) ship model# 5617 with bilge keels at different steady turning conditions. The effect of separated flows caused by the bilge keels and the skeg during steady turns on the flow distributions at the propeller plane will greatly influence the flow at the propeller planes. It was observed that during a high speed port turn at full rudder angle, the onset flow to the port side bilge keel was mainly influenced by the flow around the bow dome and the onset flow to the starboard side bilge keel was subject to the free stream hull flow. The drift angle varies along the bilge keel span during steady turning and complex vortical flow structures were developed on the leeward side of the bilge keels due to flow separations caused by the flow over the tip of the bilge keel from the windward side to the leeward side. The vortical flow generated by the starboard bilge keel also merged with the separated flow caused by the skeg and form a streamwise vortical structure that was convected downstream into the propeller plane. The wake field at both port and starboard propeller planes were analyzed from the simulation results. It can be concluded from the analysis that the starboard side propeller plane was subject to a uniform cross flow and the port side propeller plane was subject to a cross flow that consisted of both cross flow component and a mean swirl that was caused by the streamwise vortical flow generated by the flow separation upstream. The cross flow component at the propeller planes can effectively produce side force affecting the lateral motion of the ship. It can be concluded from the simulations that the bilge keels have great influence on the wake distributions at the propeller planes and can affect the propeller performance during maneuvering in terms of hydrodynamic and structural loadings. Great care should be taken to ensure that the bilge keels be designed properly in the future not just for both seakeeping and propulsion, but also for maneuvering.

scholarly journals Effect of the Particle Size of Al/Ni Multilayer Powder on the Exothermic Characterization

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4394
Author(s):  
Shugo Miyake ◽  
Taisei Izumi ◽  
Rino Yamamoto
Keyword(s):  
Particle Size ◽  
High Speed ◽  
Heat Dissipation ◽  
Local Heating ◽  
Exothermic Reaction ◽  
Thermal Characteristics ◽  
Maximum Temperature ◽  
Exothermic Reactions ◽  
Heating Source ◽  
Wide Range

In this study, the exothermic temperature performance of various Al/Ni multilayer powders with particle sizes ranging from under 75 to over 850 µm, which generate enormous heat during self-propagating exothermic reactions, was determined using a high-speed sampling pyrometer. The Al/Ni multilayer powders were prepared by a cold-rolling and pulverizing method. The multilayer constitution of the Al/Ni multilayer powders was examined by observing the cross-section of the powders using scanning electron microscopy; the results indicate that the powders had similar lamellar structures regardless of the particle size. Exothermic reactions were carried out to measure the temperature changes during the experiment using a pyrometer. We found that the maximum temperature and the duration of the exothermic reaction increased with an increase in the particle size caused by the heat dissipation of the surface area of the Al/Ni multilayer powder. This indicates that the thermal characteristics of the exothermic reaction of the Al/Ni multilayer powder can be controlled by adjusting the particle size of the Al/Ni multilayer powder. Finally, we concluded that this controllability of the exothermic phenomenon can be applied as a local heating source in a wide range of fields.

Modal Analysis on Rotor of Asynchronous Traction Motor Used in High-Speed Trains

2013 ◽  
Vol 274 ◽  
pp. 374-377
Author(s):  
Si Chen ◽  
Fang Wang ◽  
Jun Ci Cao
Keyword(s):  
High Speed ◽  
Simulation Analysis ◽  
Analysis Model ◽  
Element Analysis ◽  
Traction Motor ◽  
Simulation Research ◽  
Operating Environments ◽  
High Speed Trains ◽  
Asynchronous Traction Motor ◽  
Safety Operation

According to the suffered various impacts and vibrations of traction driving part in high-speed train under complex operating environments and conditions, the modal problems in the rotor of traction motor, power output device in traction transmission system, working in high-speed trains is investigated. In this paper, a Finite Element Analysis model for rotor modal simulation research is established, by using which the influences of structure parts on motor natural frequency is analyzed. From the simulation analysis, the natural frequencies, the vibration mode and the amplitude of each order modes are obtained, which could provide a theoretical basis for the rapid, stable and safety operation of high-speed trains.

Three-Dimensional Finite Element Analysis in Cutting Temperature for High Speed Milling of Titanium Alloys

2011 ◽  
Vol 189-193 ◽  
pp. 2259-2263
Author(s):  
You Xi Lin ◽  
Cong Ming Yan
Keyword(s):  
Finite Element ◽  
Temperature Distribution ◽  
Titanium Alloys ◽  
High Speed ◽  
Three Dimensional ◽  
Cutting Temperature ◽  
Maximum Temperature ◽  
Depth Of Cut ◽  
High Speed Milling ◽  
Radial Depth

A three dimensional fully thermal-mechanical coupled finite element model had been presented to simulate and analyze the cutting temperature for high speed milling of TiAl6V4 titanium alloy. The temperature distribution induced in the tool and the workpiece was predicted. The effects of the milling speed and radial depth of cut on the maximum cutting temperature in the tool was investigated. The results show that only a rising of temperature in the lamella of the machined surface is influenced by the milling heat. The maximum temperature in the tool increases with increasing radial depth of cut and milling speed which value is 310°C at a speed of 60 m/min and increases to 740°C at 400m/min. The maximum temperature is only effective on a concentrated area at the cutting edge and the location of the maximum temperature moves away from the tool tip for higher radial depths of milling. The predicted temperature distribution during the cutting process is consistent with the experimental results given in the literature. The results obtained from this study provide a fundamental understanding the process mechanics of HSM of titanium alloys.

FEM Analysis of Temperature in High Speed Cutting of TiAl6V4 Alloys

2012 ◽  
Vol 522 ◽  
pp. 201-205
Author(s):  
You Xi Lin ◽  
Cong Ming Yan ◽  
Zheng Ying Lin
Keyword(s):  
Temperature Distribution ◽  
High Speed ◽  
Metal Cutting ◽  
Cutting Temperature ◽  
Fem Analysis ◽  
Element Model ◽  
Maximum Temperature ◽  
Depth Of Cut ◽  
Machined Surface ◽  
Radial Depth

mprovements in modeling and simulation of metal cutting processes are required in advanced manufacturing technologies. A three dimensional fully thermal mechanical coupled finite element model had been applied to simulate and analyze the cutting temperature for high speed milling of TiAl6V4 titanium alloy. The temperature distribution induced in the tool and the workpiece was predicted. The effects of the milling speed and radial depth of cut on the maximum cutting temperature in the tool was investigated. The results show that only a rising of temperature in the lamella of the machined surface is influenced by the milling heat. The maximum temperature in the tool increases with increasing radial depth of cut and milling speed which value is 310°C at a speed of 60 m/min and increases to 740°C at 400m/min. The maximum temperature is only effective on a concentrated area at the cutting edge and the location of the maximum temperature moves away from the tool tip for higher radial depths of milling. The predicted temperature distribution during the cutting process is consistent with the experimental results given in the literature. The results obtained from this study provide a fundamental understanding the process mechanics of HSM of TiAl6V4 titanium alloys.

scholarly journals Temperature evolution of the train brake disc during high-speed braking

2019 ◽  
Vol 11 (1) ◽  
pp. 168781401881956
Author(s):  
Zhizhong Wang ◽  
Jianmin Han ◽  
Xiaolong Liu ◽  
Zhiqiang Li ◽  
Zhiyong Yang ◽  
...  
Keyword(s):  
Finite Element ◽  
Temperature Distribution ◽  
Temperature Variation ◽  
Friction Surface ◽  
High Speed ◽  
Experimental Results ◽  
Temperature Evolution ◽  
Maximum Temperature ◽  
Brake Disc ◽  
In Situ Experiments

Temperature evolution of the train brake disc during high-speed braking was investigated using in situ experiments, theoretical analysis, and finite element modeling. The experimental results show that the temperature distribution on the friction surface experienced the formation of a hot ring first, then expansion and duration of the hot ring. Alternative hot spot and cold zone were observed on the friction surface, which is attributed to the local contact in the friction couple and heterogeneous heat dissipation condition in the disc. The corresponding maximum temperature in the disc increased rapidly first, kept stable then, and decrease slowly in the end. The one-dimensional heat conduction equation was applied to predict the maximum temperature variation and was found to be in agreement with the experimental results. Furthermore, the maximum temperature evolution and the temperature distribution of the disc at the braking time of 45 s were simulated by the finite element method, which is satisfactory. In additional, the temperature variation caused the corresponding fluctuation of instantaneous frictional coefficient and thermal stress distribution in the disc, which results in the thermal damages.

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