The Effect of Drag Reduction and Other Improvements on the Design and Performance of Submerged Vehicles

1969 ◽  
pp. 313-330 ◽  
Author(s):  
Thomas G. Lang
Keyword(s):  
Drag Reduction ◽  
And Performance

Enhancing turbulence: a potential strategy for drag reduction based on ground transportation systems (GTS) model

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Xiaolong Yang ◽  
Zhuangzhi Liu ◽  
Yu Hu
Keyword(s):  
Drag Reduction ◽  
Transportation Systems ◽  
Small Scale ◽  
Content Type ◽  
Eddy Simulation ◽  
Heavy Trucks ◽  
Turbulence Transition ◽  
Potential Possibility ◽  
Potential Strategy ◽  
And Performance

Purpose The purpose of this paper is to investigate the mechanism and performance of a potential strategy, which is to enhance turbulence to carry out drag reduction for heavy trucks. Design/methodology/approach Enhancing turbulence deflector (ETD) was placed on the roof surface of an ground transportation system (GTS) to investigate the drag reduction mechanism of enhancing turbulence. Transition shear-stress transport improved delay detach eddy simulation model was adopted to simulate the unsteady small-scale flow around the ETD. Findings By optimizing the three influencing factors, diameter, streamwise length and streamwise position, the optimized ETD has achieved a maximum drag reduction of 7.04%. The analysis of flow field results shows that enhancing turbulence can effectively suppress flow separation and reduce the negative pressure intensity in the wake region of GTS. Originality/value The present work provides another potential possibility for the improvement of the aerodynamic performance of heavy trucks.

scholarly journals Comparison of Aerodynamics Characteristics of NACA 0015 & NACA 4415

2016 ◽  
Author(s):  
Robiul Islam Rubel ◽  
Md. K. Uddin ◽  
Md. Zahidul Islam ◽  
Md. Rokunuzzaman
Keyword(s):  
Drag Reduction ◽  
Numerical Investigation ◽  
Turbine Blade ◽  
Flow Separation ◽  
Aircraft Wing ◽  
Fluid Medium ◽  
Velocity Contour ◽  
Lift Enhancement ◽  
And Performance ◽  
Naca 0015

NACA 0015 and NACA 4415 aerofoil are most common four digits and broadly used aerodynamic shape. Both of the shapes are extensively used for various kind of applications including turbine blade, aircraft wing and so on. NACA 0015 is symmetrical and NACA 4415 is unsymmetrical in shape. Consequently, they have big one-of-a-kind in aerodynamic traits at the side of widespread differences of their utility and performance. Both of them undergo the same fluid principle while applied in any fluid medium giving dissimilar outcomes in aerodynamics behavior. On this work, experimental and numerical investigation of each NACA 0015 and NACA 4415 is done to decide their performance. For this purpose, aerofoil section is tested for a prevalence range attack of angle (AOA). The study addresses the performance of NACA 0015 and NACA 4415 and evaluates the dynamics of flow separation, lift, drag, pressure and velocity contour and so on. This additionally enables to layout new optimistic aerofoil, which is critical to enhance the efficiency and performance of an aircraft in terms of lift enhancement and drag reduction.

scholarly journals Active Control for Wall Drag Reduction: Methods, Mechanisms and Performance

IEEE Access ◽  
2020 ◽  
Vol 8 ◽  
pp. 7039-7057 ◽  
Author(s):  
Lu Zhang ◽  
Xiaobiao Shan ◽  
Tao Xie
Keyword(s):  
Drag Reduction ◽  
Active Control ◽  
Reduction Methods ◽  
And Performance

scholarly journals Design and Performance Evaluation of Superstructure Modification for Air Drag Reduction of a Container Ship

2015 ◽  
Vol 52 (1) ◽  
pp. 8-18 ◽  
Author(s):  
Yoonsik Kim ◽  
Kwang-Soo Kim ◽  
Seong-Wook Jeong ◽  
Seung-Gyu Jeong ◽  
Suak-Ho Van ◽  
...  
Keyword(s):  
Performance Evaluation ◽  
Drag Reduction ◽  
Container Ship ◽  
Air Drag ◽  
And Performance

Mechanism and performance of a hydrofoil bubble generator utilized for bubbly drag reduction ships

2020 ◽  
Vol 216 ◽  
pp. 108085
Author(s):  
Yuichi Murai ◽  
Haruki Sakamaki ◽  
Ichiro Kumagai ◽  
Hyun Jin Park ◽  
Yuji Tasaka
Keyword(s):  
Drag Reduction ◽  
And Performance

scholarly journals Drag Reduction and Performance Improvement of Hydraulic Torque Converters with Multiple Biological Characteristics

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Liu Chunbao ◽  
Li Li ◽  
Lei Yulong ◽  
Liu Changsuo ◽  
Zhang Yubo
Keyword(s):  
Drag Reduction ◽  
Performance Improvement ◽  
High Speed ◽  
Design Method ◽  
Torque Converter ◽  
Biological Characteristics ◽  
Dynamics Simulation ◽  
Hydraulic Torque Converter ◽  
And Performance ◽  
Profile Loss

Fish-like, dolphin-like, and bionic nonsmooth surfaces were employed in a hydraulic torque converter to achieve drag reduction and performance improvement, which were aimed at reducing profile loss, impacting loss and friction loss, respectively. YJSW335, a twin turbine torque converter, was bionically designed delicately. The biological characteristics consisted of fish-like blades in all four wheels, dolphin-like structure in the first turbine and the stator, and nonsmooth surfaces in the pump. The prediction performance of bionic YJSW335, obtained by computational fluid dynamics simulation, was improved compared with that of the original model, and then it could be proved that drag reduction had been achieved. The mechanism accounting for drag reduction of three factors was also investigated. After bionic design, the torque ratio and the highest efficiencies of YJSW335 were both advanced, which were very difficult to achieve through traditional design method. Moreover, the highest efficiency of the low speed area and high speed area is 85.65% and 86.32%, respectively. By economic matching analysis of the original and bionic powertrains, the latter can significantly reduce the fuel consumption and improve the operating economy of the loader.

Transmission Scanning Electron Microscopy and Energy Analysis with the Siemens ELMISKOP 101

1972 ◽  
Vol 30 ◽  
pp. 450-451
Author(s):  
H. M. Thieringer
Keyword(s):  
Objective Lens ◽  
Transmission Microscopy ◽  
Image Recording ◽  
Mode Of Operation ◽  
Scanning Transmission ◽  
Electron Microscopes ◽  
And Performance ◽  
Convergent Beam ◽  
Ray Path ◽  
Beam Diffraction

It has repeatedly been show that with conventional electron microscopes very fine electron probes can be produced, therefore allowing various micro-techniques such as micro recording, X-ray microanalysis and convergent beam diffraction. In this paper the function and performance of an SIEMENS ELMISKOP 101 used as a scanning transmission microscope (STEM) is described. This mode of operation has some advantages over the conventional transmission microscopy (CTEM) especially for the observation of thick specimen, in spite of somewhat longer image recording times.Fig.1 shows schematically the ray path and the additional electronics of an ELMISKOP 101 working as a STEM. With a point-cathode, and using condensor I and the objective lens as a demagnifying system, an electron probe with a half-width ob about 25 Å and a typical current of 5.10-11 amp at 100 kV can be obtained in the back focal plane of the objective lens.

Angular Resolved Electron Spectroscopy with Parallel Recording

1990 ◽  
Vol 48 (2) ◽  
pp. 370-371
Author(s):  
Huang Min ◽  
P.S. Flora ◽  
C.J. Harland ◽  
J.A. Venables
Keyword(s):  
Electron Spectroscopy ◽  
Low Voltage ◽  
Solid Angle ◽  
Detection System ◽  
Voltage Electron ◽  
Cylindrical Mirror ◽  
Inner Radius ◽  
Channel Plate ◽  
And Performance ◽  
Type Detector

A cylindrical mirror analyser (CMA) has been built with a parallel recording detection system. It is being used for angular resolved electron spectroscopy (ARES) within a SEM. The CMA has been optimised for imaging applications; the inner cylinder contains a magnetically focused and scanned, 30kV, SEM electron-optical column. The CMA has a large inner radius (50.8mm) and a large collection solid angle (Ω > 1sterad). An energy resolution (ΔE/E) of 1-2% has been achieved. The design and performance of the combination SEM/CMA instrument has been described previously and the CMA and detector system has been used for low voltage electron spectroscopy. Here we discuss the use of the CMA for ARES and present some preliminary results.The CMA has been designed for an axis-to-ring focus and uses an annular type detector. This detector consists of a channel-plate/YAG/mirror assembly which is optically coupled to either a photomultiplier for spectroscopy or a TV camera for parallel detection.

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