Numerical Study on Airfoil Diversion Technology Used in Saving Energy by Air Injection on Large Ship

The power consumption is too large when the method saving energy by air injection is used on large ship because of the deep draft. The feasibility and some key matters of the implication of airfoil diversion technology on air lubrication ,such as the attack angle, the distance from the airfoil to the plate and the position of the air injection, was investigate by a numerical method. The result shows that the pressure of the air injection entrance is significantly decreased by setting an airfoil at the air injection entrance reasonably, the pressure of the plate surface declines when the distance from the plate to the airfoil is decreasing and the attack angle is increasing, however, the resistance became larger. For the airfoil 2032cjc we investigated in this paper, when d/C=0.3, the attack angle range from 6°~8°,the pressure reduces comparative large and the resistance increases small. The best position for air injection is determined by the position and attack angle of the airfoil.

Download Full-text

Analysis of LED Backlight Design Based on Dynamic Regional Control Technology

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.739.423 ◽

2013 ◽

Vol 739 ◽

pp. 423-426

Author(s):

De Yue Cao ◽

Yi Zou

Keyword(s):

Power Consumption ◽

Reducing Power ◽

Control Technology ◽

Paper Briefly ◽

Saving Energy ◽

Regional Control ◽

Consumption And Saving ◽

Led Backlight

This paper briefly explains the advantages of LED and the classification of LED backlight and explores the pattern of LED backlight based on dynamic regional control technology to overcome and improve the inherent problems of LCD TV monitor on purpose of reducing power consumption and saving energy.

Download Full-text

Reduction of frictional resistance by air bubble lubrication

10.5957/smc-2009-009 ◽

2009 ◽

Author(s):

E. J. Foeth ◽

R. Eggers ◽

I. van der Hout ◽

F. H. H. A. Quadvlieg

Keyword(s):

Frictional Resistance ◽

Full Scale ◽

Air Injection ◽

Environmental Footprint ◽

Propulsive Efficiency ◽

Air Bubble ◽

Model Scale ◽

Air Lubrication ◽

Series Of Experiments ◽

Performance Gains

The reduction of resistance and the increase of propulsive efficiency are major drivers for ship designers both for economic reasons and increasingly for reducing the ship’s environmental footprint. Reducing the frictional resistance by air injection below the ship in combination with special coatings is an active area of research; anecdotally, performance gains are usually large. The paper gives an overview of some model scale and full scale measurements results of ships with one type of air lubrication—air bubble lubrication—performed by MARIN. The experiments were performed under the SMOOTH project. The first series of experiments focused on an inland shipping vessel that was tested both on model scale and on full scale, with and without air lubrication. A second series of tests consisted of maneuvering and seakeeping tests with a model painted with different coatings and with and without air lubrication. No appreciable effects of air bubble lubrication were found during the resistance and propulsion tests at either model or full scale and no significant effects of air bubble lubrication on maneuvering and seakeeping model tests could be determined.

Download Full-text

Implementation of DTM as a numerical study for the Casson fluid flow past an exponentially variable stretching sheet with thermal radiation

International Journal of Modern Physics C ◽

10.1142/s0129183121501114 ◽

2021 ◽

pp. 2150111

Author(s):

Khadijah M. Abualnaja

Keyword(s):

Fluid Flow ◽

Thermal Radiation ◽

Numerical Method ◽

Stretching Sheet ◽

Numerical Solutions ◽

Numerical Study ◽

Transformation Method ◽

Casson Fluid ◽

Physical Parameters ◽

Special Cases

This paper introduces a theoretical and numerical study for the problem of Casson fluid flow and heat transfer over an exponentially variable stretching sheet. Our contribution in this work can be observed in the presence of thermal radiation and the assumption of dependence of the fluid thermal conductivity on the heat. This physical problem is governed by a system of ordinary differential equations (ODEs), which is solved numerically by using the differential transformation method (DTM). This numerical method enables us to plot figures of the velocity and temperature distribution through the boundary layer region for different physical parameters. Apart from numerical solutions with the DTM, solutions to our proposed problem are also connected with studying the skin-friction coefficient. Estimates for the local Nusselt number are studied as well. The comparison of our numerical method with previously published results on similar special cases shows excellent agreement.

Download Full-text

A Numerical Study on Oil-air Lubrication of Cooling a Hot Rotating Cylinder

International Journal of Digital Content Technology and its Applications ◽

10.4156/jdcta.vol5.issue8.38 ◽

2011 ◽

Vol 5 (8) ◽

pp. 332-339 ◽

Cited By ~ 1

Author(s):

Lin Cai ◽

Jinli Wang ◽

Hongtao Zheng

Keyword(s):

Numerical Study ◽

Rotating Cylinder ◽

Air Lubrication

Download Full-text

A 2.5D numerical study on open water hydrodynamic performance of a Voith-Schneider propeller

Mechanics & Industry ◽

10.1051/meca/2019049 ◽

2019 ◽

Vol 20 (6) ◽

pp. 617

Author(s):

Mohammad Bakhtiari ◽

Hassan Ghassemi

Keyword(s):

Numerical Method ◽

Thrust Force ◽

Numerical Study ◽

Open Water ◽

Hydrodynamic Performance ◽

Maximum Efficiency ◽

Water Efficiency ◽

Blade Thickness ◽

Unsteady Rans ◽

Marine Vessels

Marine cycloidal propeller (MCP) is a special type of marine propulsors that provides high maneuverability for marine vessels. In a MCP, the propeller axis of rotation is perpendicular to the direction of thrust force. It consists of a number of lifting blade. Each blade rotates about the propeller axis and simultaneously pitches about its own axis. The magnitude and direction of thrust force can be adjusted by controlling the propeller pitch. Voith-Schneider propeller (VSP) is a low-pitch MCP with pure cycloidal blade motion allowing fast, accurate, and stepless control of thrust magnitude and direction. Generally, low-pitch cycloidal propellers are used in applications with low speed maneuvering requirements, such as tugboats, minesweepers, etc. In this study, a 2.5D numerical method based on unsteady RANS equations with SST k-ω turbulent model was implemented to predict the open water hydrodynamic performance of a VSP for different propeller pitches and blade thicknesses. The numerical method was validated against the experimental data before applying to VSP. The results showed that maximum open water efficiency of a VSP is enhanced by increasing the propeller pitch. Furthermore, the effect of blade thickness on open water efficiency is different at various advance coefficients, so that the maximum efficiency produced by the VSP decreases with increasing blade thickness at different propeller pitches.

Download Full-text

Numerical Method for Studying Bearing Gap Pressure Wave Development and Subsequent Performance Mapping of Externally Pressurized Gas Journal Bearings

Volume 3B: Fluid Applications and Systems ◽

10.1115/ajkfluids2019-4732 ◽

2019 ◽

Author(s):

Tom M. Lawrence ◽

Marvin D. Kemple

Keyword(s):

Numerical Method ◽

Cross Section ◽

Mass Flow ◽

Pressure Wave ◽

Design Space ◽

Numerical Study ◽

Pressure Waves ◽

Wide Range ◽

Wave Development ◽

Static Instability

Abstract In previous work, numerical methods were developed to determine the pressure waves (pressure distribution) in the bearing gap of round externally pressurized gas bearings (EPB’s) that were pressurized through porous liners (PL bearings) or through liners with rows of feedholes (FH bearings). When integrated and differentiated these pressure portraits yield the net hydrodynamic force (FH) between the shaft and the bushing and the mass flow rates through the bearing gap. These results successfully replicated force-deflection curves and mass flow rate data for experimentally tested prototype FH and PL bearings over a wide range of mass flow constriction and clearances. Subsequently the numerical study was expanded to a broader design space of clearance and mass flow compensation. Also, a bearing performance mapping method of mapping the normalized bearing load over the clearance-eccentric deflection plane was developed for different levels of mass compensation. These performance maps produced a very interesting result as they indicated certain areas in the design space of FH bearings where static instability (negative stiffness) would be encountered. This static instability was not observed in the experimental data but is noted in references as known to occur in practice. Because this numerical method is based on the development of pressure wave portraits, the FH pressure wave could then be “dissected” in the areas of the onset of static instability which gave much insight as to the possible causes of static instability. This initial work, then, was perhaps the first to predict where in design space static instability would occur and yield some insight via examination of the corresponding pressure waves as to the cause. The numeric techniques developed, however are in no way limited to non-rotating bearings but are extensible to rotating bearings. The method is also easily extensible to examination of any configuration of feedholes or orifices. Nor is it limited to parallel deflections but can yield results for unbalanced loads. The method is also not limited to round bearings but can be applied to any cross-section configuration of bearing gap cross section such as a 3 lobed bearing or a slotted 3 lobed bearing. Examination of the resulting pressure wave development patterns for different scenarios can be examined to garner insight as to the causes of differing performance that can be applied to alterations towards optimization. Thus sharing in detail the developed numerical method underlying these studies seems worthwhile.

Download Full-text

Aeroelastic Analysis of Oscillatory Blowing Control of the Airfoil’s Flutter at Large Attack Angle

5th International Symposium on Fluid Structure International, Aeroeslasticity, and Flow Induced Vibration and Noise ◽

10.1115/imece2002-32995 ◽

2002 ◽

Author(s):

Jin Yan ◽

Yuan Xin

Keyword(s):

Numerical Method ◽

Flow Separation ◽

Lift Coefficient ◽

High Accuracy ◽

Numerical Results ◽

Attack Angle ◽

Fluid Structure ◽

Aeroelastic Analysis

It is known that oscillatory blowing on the back of an airfoil can delay the flow separation and the stall. The purpose of the present paper is to apply the oscillatory blowing technique to the control of the airfoil’s flutter. High accuracy, high solution fluid-structure coupling numerical method is used in the study. The numerical results show that the steady blowing will weaken the flutter, but at the same time the excess blowing will make the lift coefficient to drop. The best blowing velocity can be found by the present numerical method. The influence of the frequency and the amplitude of the oscillatory blowing on the airfoil’s vibration is studied in the paper. The numerical results show that the oscillatory blowing is more efficient in the cases of flutter than steady blowing.

Download Full-text

Numerical study of fluid flow and power consumption in a stirred vessel with a Scaba 6SRGT impeller

Chemical and Process Engineering ◽

10.2478/v10176-011-0028-0 ◽

2011 ◽

Vol 32 (4) ◽

pp. 351-366 ◽

Cited By ~ 16

Author(s):

Houari Ameur ◽

Mohamed Bouzit ◽

Mustapha Helmaoui

Keyword(s):

Experimental Data ◽

Fluid Flow ◽

Power Consumption ◽

Yield Stress ◽

Short Distance ◽

Numerical Study ◽

Stirred Vessel ◽

Higher Power ◽

Shear Thinning Fluid ◽

Good Agreement

Numerical study of fluid flow and power consumption in a stirred vessel with a Scaba 6SRGT impeller The present work deals with agitation of non-Newtonian fluids in a stirred vessel by Scaba impellers. A commercial CFD package (CFX 12.0) was used to solve the 3D hydrodynamics and to characterise at every point flow patterns especially in the region swept by the impeller. A shear thinning fluid with yield stress was modelled. The influence of agitator speed, impeller location and blade size on the fluid flow and power consumption was investigated. The results obtained are compared with available experimental data and a good agreement is observed. It was found that an increase in blade size is beneficial to enlargement of the well stirred region, but that results in an increased power consumption. A short distance between the impeller and the tank walls limits the flow around the agitator and yields higher power consumption. Thus, the precise middle of the tank is the most appropriate position for this kind of impeller.

Download Full-text