A Numerical Study of the Drag Reduction of a Transonic Projectile with Porous Surfaces and Slots

2006 ◽  
Author(s):  
Ahmed Ibrahim ◽  
Antonio Filippone
Keyword(s):  
Drag Reduction ◽  
Numerical Study ◽  
Porous Surfaces

Numerical study on the mechanism of drag reduction for interceptors on planning boats

2021 ◽  
Author(s):  
Lianzheng Cui ◽  
Zuogang Chen ◽  
Yukun Feng
Keyword(s):  
Drag Reduction ◽  
High Speed ◽  
Degrees Of Freedom ◽  
Numerical Study ◽  
Dynamic Pressure ◽  
Motion Model ◽  
Gauge Pressure ◽  
Reduction Effect ◽  
Pressure Resistance ◽  
Viscous Pressure

The drag reduction effect of interceptors on planning boats has been widely proven, but the mechanism of the effect has been rarely studied in terms of drag components, especially for spray resistance. The resistance was caused by the high gauge pressure under the boats transformed from the dynamic pressure, and it is the largest drag component in the high-speed planning mode. In this study, numerical simulations of viscous flow fields around a planning boat with and without interceptors were conducted. A two degrees of freedom motion model was employed to simulate the trim and sinkage. The numerical results were validated against the experimental data. The flow details with and without the interceptor were visualized and compared to reveal the underlying physics. A thinner and longer waterline could be achieved by the interceptor, which made the boat push the water away more gradually, and hence, the wave-making resistance could be decreased. The improved waterline also reduced the component of the freestream normal to the hull surface and led to the less transformed dynamic pressure, resulting in the lowAer spray resistance. Furthermore, the suppression of the flow separation could also be benefited from the interceptor; the viscous pressure resistance was therefore decreased.

scholarly journals Numerical Study of the Generic Sports Utility Vehicle Design with a Drag Reduction Add-On Device

2014 ◽  
Vol 2014 ◽  
pp. 1-17 ◽  
Author(s):  
Shubham Singh ◽  
M. Zunaid ◽  
Naushad Ahmad Ansari ◽  
Shikha Bahirani ◽  
Sumit Dhall ◽  
...  
Keyword(s):  
Drag Reduction ◽  
Drag Coefficient ◽  
Aerodynamic Drag ◽  
Numerical Study ◽  
Fuel Efficiency ◽  
Ansys Fluent ◽  
Mean Pressure ◽  
Aerodynamic Drag Coefficient ◽  
Total Base ◽  
Aerodynamic Parameters

CFD simulations using ANSYS FLUENT 6.3.26 have been performed on a generic SUV design and the settings are validated using the experimental results investigated by Khalighi. Moreover, an add-on inspired by the concept presented by Englar at GTRI for drag reduction has been designed and added to the generic SUV design. CFD results of add-on model and the basic SUV model have been compared for a number of aerodynamic parameters. Also drag coefficient, drag force, mean surface pressure, mean velocities, and Cp values at different locations in the wake have been compared for both models. The main objective of the study is to present a new add-on device which may be used on SUVs for increasing the fuel efficiency of the vehicle. Mean pressure results show an increase in the total base pressure on the SUV after using the device. An overall reduction of 8% in the aerodynamic drag coefficient on the add-on SUV has been investigated analytically in this study.

A Critical Review of Drag Reduction in Channel Flows and Numerical Study of Forced Convective Transport in a Channel With Conducting-Lubricating (CO-LUB) Surfaces

2015 ◽  
Author(s):  
Jessica Reyes ◽  
Krishna Kota
Keyword(s):  
Heat Transfer ◽  
Drag Reduction ◽  
Liquid Flow ◽  
Numerical Study ◽  
Rectangular Channel ◽  
Narrow Channel ◽  
Convective Transport ◽  
Bulk Liquid ◽  
Frictional Drag ◽  
Ansys Fluent

Addressing the traditionally contradictory problem of obtaining considerable drag reduction without negatively impacting heat transfer as much is an arduous scientific challenge. In this paper, prior efforts on frictional drag reduction and the associated issues are discussed in relevant detail, and the effectiveness of Conducting-Lubricating (CO-LUB) surfaces as one of the potential options to address this challenge for single phase forced convection of liquids is numerically pursued. CO-LUB surfaces have exceptionally high wetting characteristics, and when saturated with a liquid microlayer, provide remarkable lubrication to bulk liquid flow and simultaneously facilitate heat transfer by conduction through the microlayer. In the simulations, the side walls of a high aspect ratio rectangular channel were assumed as CO-LUB surfaces and flow and heat transfer of bulk liquid flow were modeled using ANSYS FLUENT 14.5. Volume-of-Fluid (VOF) method was used to model the two phases with a free surface interface, with water as the microlayer liquid and oil as the bulk liquid, in a narrow channel of 5 mm width and 50 mm length under laminar flow, constant wall heat flux conditions. The results were compared with a regular channel of the same dimensions (without CO-LUB surfaces) and it was found that pressure drop decreased remarkably by ∼23 times for some cases but without any heat transfer attenuation (actually, improved heat transfer performance was observed) leading to highly energy-efficient convective transport.

Numerical Study on Mechanism of Drag Reduction by Microblowing Technique on Supercritical Airfoil

2017 ◽  
Vol 30 (3) ◽  
pp. 04016084 ◽  
Author(s):  
Zhenxun Gao ◽  
Junxuan Cai ◽  
Jian Li ◽  
Chongwen Jiang ◽  
Chun-Hian Lee
Keyword(s):  
Drag Reduction ◽  
Numerical Study ◽  
Supercritical Airfoil

Slippery liquid-infused substrates: a versatile preparation, unique anti-wetting and drag-reduction effect on water

2016 ◽  
Vol 4 (7) ◽  
pp. 2524-2529 ◽  
Author(s):  
Yang Wang ◽  
Haifeng Zhang ◽  
Xiaowei Liu ◽  
Zhiping Zhou
Keyword(s):  
Drag Reduction ◽  
Porous Surfaces ◽  
Reduction Effect

Newly developed slippery liquid-infused porous surfaces (SLIPSs) are highly promising for a broad range of applications.

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