Experimental and numerical investigations of the vehicle aerodynamic drag with single-channel rear diffuser

2020 ◽  
Vol 234 (8) ◽  
pp. 2216-2227 ◽  
Author(s):  
Huang Taiming ◽  
Zhuang Xiaodong ◽  
Wan Zhongmin ◽  
Gu Zhengqi
Keyword(s):  
Single Channel ◽  
Aerodynamic Drag ◽  
Wind Tunnel Test ◽  
Aerodynamic Performance ◽  
Channel Width ◽  
Structure Parameters ◽  
Reduction Mechanism ◽  
Numerical Investigations ◽  
Diffuser Angle ◽  
The Relationship

The main purpose of this paper is to reveal the drag reduction mechanism of single-channel rear diffuser on the vehicle aerodynamic drag and to obtain the relationship between the structure parameters of rear diffuser and the vehicle aerodynamic drag. The influence of the single-channel rear diffuser on the aerodynamic drag is studied using the Reynolds-averaged method with the 25° slant Ahmed model. The accuracy of the numerical method is validated by means of a wind tunnel test. The aerodynamic performance of the Ahmed model with different vertical diffuser angles, lateral diffuser angles, and channel widths is discussed. The results demonstrate that the vortex location will be influenced by the vertical diffuser angle, and with the vortex core approaching to the model, the aerodynamic drag will increase. The aerodynamic drag reaches the minimum value with a vertical diffuser angle of 10.46°. Moreover, the aerodynamic drag decreases with increasing channel width. Finally, the aerodynamic drag can be reduced by 5.3%, when the vertical diffuser angle, lateral diffuser angle, and channel width are 10.46°, 0°, and 351 mm, respectively.

Aerodynamic Drag Reduction of SUV Based on Underbody Cover Board

2014 ◽  
Vol 602-605 ◽  
pp. 477-480
Author(s):  
Jing Yu Wang ◽  
Bao Yu Wang ◽  
Xing Jun Hu ◽  
Lei Liao
Keyword(s):  
Flow Field ◽  
Drag Reduction ◽  
Drag Coefficient ◽  
Aerodynamic Drag ◽  
Flow Line ◽  
Wind Tunnel Test ◽  
Aerodynamic Performance ◽  
Simulation Based ◽  
Aerodynamic Drag Coefficient ◽  
Aerodynamic Drag Reduction

The principles and method of computational fluid dynamics were applied to numerical simulate the external flow field about the SUV model. The hybrid mesh of tetrahedral and triangular prismatic as well as the turbulence model of Realizable k-ε was adopted to study the flow field of SUV of flat underground. Then the SUV of complex underground was simulated with the same mesh strategy and boundary condition. The aerodynamic drag coefficient of latter was bigger than former. That illuminated the complex underground has affect to aerodynamic performance of vehicle. The wind tunnel test validated the veracity of numerical simulation. Based on that, the underground cover board was appended; the aerodynamic drag coefficient was depressed. The velocity and pressure distribution and flow line were achieved. The conclusions provide theoretical reference for the further study of aerodynamic drag reduction of complex underground.

scholarly journals Experimental-numerical studies of the effect of cell structure on the mechanical properties of polypropylene foams

e-Polymers ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 713-723
Author(s):  
Wei Gong ◽  
Tuan-Hui Jiang ◽  
Xiang-Bu Zeng ◽  
Li He ◽  
Chun Zhang
Keyword(s):  
Mechanical Properties ◽  
Size Distribution ◽  
Cell Size ◽  
Cell Structure ◽  
Structure Parameters ◽  
Cell Size Distribution ◽  
Numerical Studies ◽  
Polypropylene Foam ◽  
The Impact ◽  
The Relationship

AbstractThe effects of the cell size and distribution on the mechanical properties of polypropylene foam were simulated and analyzed by finite element modeling with ANSYS and supporting experiments. The results show that the reduced cell size and narrow size distribution have beneficial influences on both the tensile and impact strengths. Decreasing the cell size or narrowing the cell size distribution was more effective for increasing the impact strength than the tensile strength in the same case. The relationship between the mechanical properties and cell structure parameters has a good correlation with the theoretical model.

scholarly journals Aerodynamic Performance of Road Vehicles

2020 ◽  
Vol 9 (6) ◽  
pp. 642-645
Keyword(s):  
Wind Tunnel ◽  
Drag Force ◽  
Aerodynamic Drag ◽  
Aerodynamic Performance ◽  
Polished Surface ◽  
Anova Analysis ◽  
Road Vehicles ◽  
Car Model ◽  
Group Data ◽  
Scale Models

Aerodynamic drag has been experimentally estimated for scale models of a passenger car and a commercial truck in a wind tunnel. Polished surface has resulted up to 15 % reduction in drag force and add-on has resulted in 57% increase in drag force of a car model whereas 2.6 % reduction in drag force has resulted by using deflector in a commercial truck model. Anova analysis shows variation in mean of group data.

scholarly journals Comparison of the Influences of Surface Texture and Boundary Slip on Tribological Performances

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Qiyin Lin ◽  
Baotong Li
Keyword(s):  
Surface Texture ◽  
Slip Velocity ◽  
Structure Parameters ◽  
Textured Surfaces ◽  
Slider Bearing ◽  
Boundary Slip ◽  
Surface Textures ◽  
Slip Surfaces ◽  
Texture Structure ◽  
The Relationship

Close attentions have been widely paid to the engineering textured and slip surfaces for improving bearing tribological performances. Comparison studies on the tribological characteristics of slip and textured surfaces are carried out in this work. The analysis results point out that the influences of surface texture and boundary slip on tribological performances of slider bearing are strongly similar. For the determinate surface textures, there is one and only value of slip velocity to make the tribological performances of textured and slip surfaces in agreement. The corresponding relation between the slip velocity and the texture structure parameters is also obtained, and the size of slip velocity is directly related to the texture geometry parameters including its position parameters. This study will help us to further understand the relationship between boundary slip and surface texture and also the slip phenomenon.

Preliminary Study of Fuel Injector Monitoring System by I-KazTM Multilevel Analysis

2013 ◽  
Vol 471 ◽  
pp. 229-234
Author(s):  
Zailan Karim ◽  
M.A. Jusoh ◽  
A.R. Bahari ◽  
Mohd Zaki Nuawi ◽  
Jaharah Abd. Ghani ◽  
...  
Keyword(s):  
Monitoring System ◽  
Single Channel ◽  
Injection System ◽  
Fuel Injector ◽  
Monitoring Method ◽  
Engine Operation ◽  
Automotive Engine ◽  
Actual Operation ◽  
Pressure Bar ◽  
The Relationship

Fuel injector in automotive engine is a very important component in injecting the correct amount of fuel into the combustion chamber. The injection system need to be in a very safe and optimum condition during the engine operation. The mulfunction of the injection system can be avoided if the current working condition is known and a proper maintenence procedure is implemented. This paper proposes the development of a fuel injector monitoring method using strain signals captured by a single-channel strain gage attached on the fuel injector body. The fuel injector was operated under three main sets of parameters; pulse width (ms), frequency (Hz) and pressure (bar) which were varried from 5 ms to 15 ms, 17 Hz to 25 Hz and 10 bar to 70 bar respectively. The settings produce 27 different engine operations and the strain signal will be captured at each operation. The captured strain signals will be analyzed using I-kazTM Multilevel technique and will be correlated with the main parameters. The relationship between the I-kazTM Multilevel coefficient and the main parameters indicate good correlations which can be used as the guidance for fuel injector monitoring during actual operation. The I-kaz Multilevel technique was found to be very suitable in this study since it is capable of showing consistence pattern change at every parameter change during the engine operation. This monitoring system has a big potential to be developed and improved for the optimization of fuel injector system performance in the automotive industry.

A Sacrificial Method for Fabricating Microchannel Accelerated by Galvanic Corrosion

2005 ◽  
Author(s):  
Hongjun Zeng ◽  
Alan Feinerman ◽  
Zhiliang Wan
Keyword(s):  
Cross Section ◽  
Etch Rate ◽  
Galvanic Corrosion ◽  
Channel Width ◽  
Etching Time ◽  
Sem Images ◽  
Sacrificial Material ◽  
Relationship Of ◽  
The Relationship

A metal sacrificial method has been investigated for creation of microchannels by galvanic corrosion in a metal multilayer. To achieve the fastest sacrificial metal combination, different metals and the corresponding etchants are chosen. Channels from 50 μm to 1 μm wide, 0.2 μm high, and 1500 μm long, as well as the channel array is fabricated, using Cr/Cu galvanic metal couple as sacrificial material. The relationship between the etching front vs. the etching time, and the relationship of the etch rate vs. channel width is measured and compared with the etching performance of the single metal. The measurement shows there is approximately 10 times faster etching in the galvanic coupled metals than that in the single metal. SEM images of the channels and channel array made by this method are presented. This method is compatible with the conventional VLSI process, and has the potential for fabricating microchannels with submicron or even nanometer cross section.

scholarly journals Wind tunnel investigation on the dust emission characteristics of high moisture coal piles

2020 ◽  
Vol 145 ◽  
pp. 02019
Author(s):  
Ningning Hong ◽  
Shitao Peng ◽  
Hongxin Zhao ◽  
Ning Su
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Moisture Content ◽  
Coal Dust ◽  
Dust Emission ◽  
Wind Tunnel Test ◽  
High Moisture Content ◽  
High Moisture ◽  
Emission Behavior ◽  
The Relationship

With the increasing requirements of environmental protection, a large number of new wet dust suppression technologies are used in the port in recent years, such as watering at the bottom of the Dumper Shed, etc. So the moisture content of coal is more than 10% often appear. Relevant studies show that the amount of dust from coal (conventional moisture content) pile is directly proportional to the high power of wind speed. But studies on high moisture content coal are rare. In this study, Wind tunnel test was carried out to study the dust emission behavior of coal with high moisture content (13.7% and 14.3%). The results show that the relationship between coal dust and wind speed tends to be linear under high moisture content. The study can provide a basis research for the estimation of coal dust emission in port.

scholarly journals Effect of NS-DBD Actuator Parameters on the Aerodynamic Performance of a Flap Lifting Device

2019 ◽  
Vol 9 (23) ◽  
pp. 5213 ◽  
Author(s):  
Kun Chen ◽  
Chen-Yao Wei ◽  
Zhi-Wei Shi
Keyword(s):  
Energy Density ◽  
Flow Field ◽  
Drag Reduction ◽  
Pulse Width ◽  
High Efficiency ◽  
Aerodynamic Drag ◽  
Pulse Discharge ◽  
Excitation Frequency ◽  
Aerodynamic Performance ◽  
Discharge Pulse

The flap lift device is an important part of the conventional configuration of aircrafts and has an important impact on the aerodynamic performance. In this paper, a high-efficiency, simple, and energy-saving nanosecond dielectric barrier discharge (DBD) plasma actuator is placed in the vicinity of the flap lift device to improve the aerodynamic performance of the flap by controlling the flow field. The two-dimensional airfoil GAW-1 and its 29% flap were selected as the research objects, and the nanosecond (NS) DBD actuators were fixed at different locations near the deflection angle of the 10°flap. The excitation frequency, pulse width, and energy density parameters of the pulse discharge were adjusted, and then, the effects of parameter changes on aerodynamic characteristics of the airfoil were studied by numerical simulation. The simulation results show that adjusting the excitation frequency on the aerodynamic drag is weak and that the effect on the aerodynamic lift is obvious. The increase of the discharge pulse width will have a more significant effect on the flow field, i.e., a proper increase of the discharge pulse width can achieve better drag reduction, and increase lift after a stall at a high angle of attack. Although the increase of discharge energy density can strengthen the pulse perturbation effect on the flow field, it also contributes to some adverse effects and has no obvious optimization effect on the control efficiency of lift increase and drag reduction.

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