Drag Reduction of Ground Vehicles Using Air-Injected Wheel Deflectors

2019 ◽  
Author(s):  
Kaloki L. Nabutola ◽  
Sandra K. S. Boetcher
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Drag Coefficient ◽  
Parametric Study ◽  
Ground Vehicles ◽  
Ground Vehicle ◽  
Flow Modification ◽  
Air Jets ◽  
Air Jet ◽  
The Impact

Abstract Numerical simulations of flow modification devices on a simplified ground vehicle are conducted. A parametric study on the size and distance upstream of conventional wheel deflectors is conducted on a simplified body at a Reynolds number of 1.6 × 105 to observe the impact on drag coefficient. Results show that wheel drag is decreased as the height of the conventional wheel deflector is increased. Additionally, the further the conventional wheel deflector is from the wheelhouse, the more sensitive the wheel is to changes in drag coefficient. The conventional wheel deflectors are then replaced by air-jets which are used to manipulate the flow field in and near the wheelhouse to reduce the wheel drag of the simplified body. The air-jet successfully decreases the wheel drag and it is observed that the closer the air-jet is to the wheelhouse the less impact it has on the single wheel drag, but the greater the impact on the overall drag of the simplified body.

scholarly journals Numerical simulation and experimental research of cavitation nozzle based on equation curve

2021 ◽  
Author(s):  
Lifu Wang ◽  
Dongyan Shi ◽  
Zhixun Yang ◽  
Guangliang Li ◽  
Chunlong Ma ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Flow Field ◽  
High Speed ◽  
Quadratic Equation ◽  
Outer Contour ◽  
Study Results ◽  
Fluent Software ◽  
The Impact ◽  
Better Than

Abstract To further investigate and improve the cleaning ability of the cavitation nozzle, this paper proposes a new model that is based on the Helmholtz nozzle and with the quadratic equation curve as the outer contour of the cavitation chamber. First, the numerical simulation of the flow field in the nozzle chamber was conducted using FLUENT software to analyze and compare the impact of the curve parameters and Reynolds number on the cleaning effect. Next, the flow field was captured by a high-speed camera in order to study the cavitation cycle and evolution process. Then, experiments were performed to compare the cleaning effect of the new nozzle with that of the Helmholtz nozzle. The study results demonstrate that effective cavitation does not occur when the diameter of the cavitation chamber is too large. For the new nozzle, with the increase of the Reynolds number, the degree of cavitation in the chamber first increases and then decreases; the cleaning effect is much better than that of a traditional Helmholtz nozzle under the same conditions; the nozzle has the best cleaning effect for the stand-off distance of 300 mm.

Entrainment by Turbulent Jets Issuing From Sharp-Edged Inlet Round Nozzles

1987 ◽  
Vol 109 (3) ◽  
pp. 248-254 ◽  
Author(s):  
T. A. Trabold ◽  
E. B. Esen ◽  
N. T. Obot
Keyword(s):  
Reynolds Number ◽  
Nozzle Exit ◽  
Parametric Study ◽  
Turbulent Jets ◽  
Plenum Chamber ◽  
Nozzle Length ◽  
Air Jets ◽  
Partial Confinement ◽  
Chamber Measurements

Experiments were carried out to determine entrainment rates by turbulent air jets generated with square-edged inlet round nozzles. A parametric study was made which included the effects of Reynolds number, nozzle length, partial confinement and geometry of the jet plenum chamber. Measurements were made for the region extending from the nozzle exit to 24 jet hole diameters downstream. There is a large difference in the rate of fluid entrainment between jets generated with relatively short nozzles and those discharged through long tubes.

Numerical Investigation on Visualizations of Confined Air Flow in a Slot Jet Inside a Rectangular Channel

2015 ◽  
Vol 813-814 ◽  
pp. 736-741
Author(s):  
M. Muthukannan ◽  
P. Rajesh Kanna ◽  
S. Jeyakumar ◽  
J.Y. Raja Shangaravel ◽  
S. Raghu ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Numerical Investigation ◽  
Rectangular Channel ◽  
Reynolds Numbers ◽  
Vortex Center ◽  
Computational Domain ◽  
Reattachment Length ◽  
Aspect Ratios ◽  
Air Jet

In the present numerical investigation, the flow field of confined slot air jet in a rectangular computational domain is reported. In the present work the flow field parameters like reattachment length, vortex center and horizontal velocity profiles for various Reynolds numbers and for various aspect ratios are presented .The present study reveals that the vortex centers are moving in a downstream direction with increase in Reynolds number. The reattachment length is directly dependent on the Reynolds numbers. In case of vortex dynamics, the vortex size is indirectly dependent on the inlet jet width. In the present investigation, SIMPLE algorithm is used to solve the governing equations. It is concluded that the aspect ratio and the Reynolds number are playing dominant roles in flow field of the present computational domain.

Flow Around Three Side-by-Side Square Cylinders and the Effect of the Cylinder Oscillation

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Bhupendra Singh More ◽  
Sushanta Dutta ◽  
Bhupendra Kumar Gandhi
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Drag Coefficient ◽  
Flow Structure ◽  
Power Spectra ◽  
Square Cylinders ◽  
Spacing Ratio ◽  
Hotwire Anemometry ◽  
Visualization Techniques ◽  
Flow Interference

Abstract In this study, the flow field over three square cylinders (SCs) arranged side by side is investigated in a low-speed wind tunnel. The experiments are performed with three similar SCs for Reynolds number (Re) 295. The influences of spacing ratio on the wake size, drag coefficient, and flow interference of the cylinders are reported with the hotwire anemometry, particle image velocimetry (PIV), and the flow visualization techniques. Special attention is paid to the oscillation given to the middle cylinder and its effect on flow structure and related forces. The spacing ratio (s/D) ranges from 1.5 to 3, whereas the forcing frequency ratio ranges from 0.5 to 2 with amplitude of 10% of the cylinder width. It is observed that the spacing influences the flow structure, and the vortex shedding mechanism strongly. A secondary frequency appears in the flow field for spacing ratio s/D = 2 and 3. Depending upon the spacing ratios, the flow pattern is seen to be asymmetric biased, symmetric biased, and weakly interactive. The wake interaction decreases with increase in spacing ratios. With the oscillations, the wake becomes more unstable and complex. Additional wake oscillation frequency appears in the power spectra. With an increase in spacing ratios, the drag coefficient decreases, whereas with oscillations, higher drag force is observed compared to a stationary cylinder. A correlation is developed between the time-averaged drag coefficient with cylinder spacing and Reynolds number.

The Effect of Rotary Arms on Corotating Disk Flow

1995 ◽  
Vol 117 (2) ◽  
pp. 259-262 ◽  
Author(s):  
John Girard ◽  
Scott Abrahamson ◽  
Kevin Uznanski
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Radial Flow ◽  
Disk Drives ◽  
Number Range ◽  
Reynolds Number Range ◽  
Through Flow ◽  
Dominant Feature ◽  
Flow Visualizations ◽  
The Impact

This investigation studied the impact of rotary style arms on the flow between corotating disks contained by a stationary cylindrical enclosure. Both ventilated and nonventilated hub configurations were considered. The particular geometry used represents a simplified model for common disk drives. Flow visualizations were performed over the Reynolds number range of 3.4 × 104 to 3.4 × 105. The arms were observed to dramatically alter the flow field and to produce an azimuthal pressure gradient throughout the flow field. The dominant feature of the flow between two disks was the arm wake. Moreover, an exchange of fluid across the shroud opening, which provided arm access, was observed. Arm effects became stronger as the arm tips were positioned closer to the hub. The combination of arms and radial through flow was studied over a similar Reynolds number range. In this case, the flow field remained dominated by arm effects, although some effects arising from the radial flow were observed.

Heat Transfer Investigation with Multiple Jet Impingement

2020 ◽  
Vol 12 (3) ◽  
Author(s):  
Niranjan Murthy ◽  
B.K. Naveenkumar
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Reynolds Number ◽  
Research Work ◽  
Jet Impingement ◽  
Test Surface ◽  
Simple Relationship ◽  
Flux Flow ◽  
Air Jets ◽  
Air Jet

An experimental study was carried out to study the effect of multiple jet impingement on a virtual electronic component using water and air as working fluids. It consists of an electrically heated test plate of size 20mm×20mm. Heat flux is varied between 25 to 250W/cm2 was dissipated using 0.25 and 0.5mm diameter jets placed in a 7×7 array with a pitch of 3mm. The difference in temperature between test surface and fluid inlet is within 30 degC for water jets and within 75 degC for air jet experiments. Experiments were conducted by changing the heat flux, flow rate and distance between the test surface and jet exit and [iv] horizontal and vertical positioning of the jets. It was found that heat flux, jet diameter and Reynolds number are important factors in determining the heat transfer. The effects of distance between test surface and jet exit [Z] and positioning of the jets were insignificant. Though the multiple jet impingement heat transfer problem is complex, the heat transfer results could be correlated using a simple relationship in the form of Nu = AqmRen. The constant (m) which indicates the effect of heat flux has the value of 0.8 and 0.9 depending upon the jet diameter and the coolant. The constant (n) which indicates the influence of Reynolds number has the value of 0.25 for both water and air jets. The value of constant (A) is different for water and air jets. The correlation developed in this research work can be effectively used to design multiple water and air jet cooling system for electronic components.

The Forces on a Cylinder Oscillating Sinusoidally in Water: Further Experiments

1978 ◽  
Vol 100 (3) ◽  
pp. 297-301
Author(s):  
C. Dalton ◽  
J. P. Hunt ◽  
A. K. M. F. Hussain
Keyword(s):  
Reynolds Number ◽  
Continuous Function ◽  
Drag Coefficient ◽  
Steady Flow ◽  
Parametric Study ◽  
Reynolds Numbers ◽  
Wave Forces ◽  
Force Coefficient ◽  
Low Reynolds Numbers ◽  
Flow Drag

This paper deals with wave forces on a single cylinder. The wave forces are simulated in a laboratory by oscillating a cylinder sinusoidally in water otherwise at rest. This effort is a parametric study relating a force coefficient to such variables as instantaneous Reynolds number, period parameter, and d/νT. The force is not decomposed into drag and inertia components, but is represented as a continuous function of the previously mentioned parameters. The idea is to determine how the acceleration affects the force. Considerable deviation from a Reynolds-number only dependence is noted for low Reynolds numbers. The steady-flow drag coefficient value is asymptotically obtained for large Reynolds numbers.

scholarly journals Experimental Study of Twin Connected Pipe Jets

2020 ◽  
Vol 5 (12) ◽  
pp. 140-144
Author(s):  
Shams Sourav ◽  
Ashraful Hossain Rifat ◽  
Muhammed Hasnain Kabir Nayeem ◽  
Md. Abu Taher Ali
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Static Pressure ◽  
Recirculation Region ◽  
Central Plane ◽  
Mean Velocity ◽  
Air Jet ◽  
Velocity Flow ◽  
The Mean ◽  
Energy And Momentum

Two parallel pipe jets of 20 mm diameter were placed 1.2 mm diameter apart and were connected by a 4 mm wide channel all along the central plane of the jets. The mean velocity flow field of the jets was investigated for three Reynolds number 16300, 34400 and 49200. The Reynolds number was based on the exit velocity of the jets and jet diameter. The experiment was performed in an air jet facility and yaw meter was used for measurement of mean velocity and its direction. Their variations along the longitudinal, transverse, and lateral directions have been analyzed. A significant change of the jet flow field is observed near the exit of the jet. The combined effect of the jets diminishes the presence of recirculation region at the immediate exit rather enhances the energy and momentum transfer between their individual flow fields. Static pressure and kinetic energy distribution are also studied and a momentous variations have been noticed with varying Reynolds number.

Magnetic surveying with an unmanned ground vehicle

2018 ◽  
Vol 6 (4) ◽  
pp. 249-266
Author(s):  
A. Hay ◽  
C. Samson ◽  
L. Tuck ◽  
A. Ellery
Keyword(s):  
Separation Distance ◽  
Field Conditions ◽  
Unmanned Ground Vehicle ◽  
Ground Vehicles ◽  
Ground Vehicle ◽  
Development Platform ◽  
Full Speed ◽  
Aerial Vehicle ◽  
The Impact ◽  
Vehicle Market

With the recent proliferation of unmanned aerial vehicles for geophysical surveying, a novel opportunity exists to develop unmanned ground vehicles in parallel. This contribution features a study to integrate the Husky A200 robotic development platform with a GSMP 35U magnetometer that has recently been developed for the unmanned aerial vehicle market. Methods to identify and reduce the impact of magnetically noisy components on the unmanned ground vehicle platforms are discussed. The noise generated by the platform in laboratory and gentle field conditions, estimated using the fourth difference method for a magnetometer–vehicle separation distance of 121 cm and rotation of the chassis wheels at full speed (1 m/s), is ±1.97 nT. The integrated unmanned ground vehicle was used to conduct two robotic magnetic surveys to map cultural targets and natural variations of the magnetic field. In realistic field conditions, at a full speed of 1 m/s, the unmanned ground vehicle measured total magnetic intensity over a range of 1730 nT at 0.1 m spatial resolution with a productivity of 2651 line metres per hour.

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