Proceedings of the
International Conference on Mechanical Engineering 2009
(ICME2009) 26- 28 December 2009, Dhaka, Bangladesh

ICME09-FM-36

ANALYSIS OF A NEGATIVELY BUOYANT JET

Chandan Kumar, D. Das and M.M. Razzaque
Department of Mechanical Engineering, Bangladesh University of Engineering and Technology (BUET),
Dhaka, Bangladesh.

ABSTRACT

The behavior of plane fountains, resulting from the injection of dense fluid (water) upwards into a large container of homogeneous fluid of lower density (air), is investigated. In this study we experimentally examine the behavior of fountains for different Froude and Reynolds numbers. The fountain inlet flow rate and nozzle diameter of the inlet fluid is varied to cover a wide range of Reynolds and Froude numbers. Fountain behavior is observed by changing the inclination angle of the fountain for different nozzle diameter and flow rate. We found that the penetration height greatly depends on Froude number. We develop an empirical correlation of the non-dimensional fountain height with Froude number (H/r =1.452Fr1.94). But well defined by both Reynolds and Froude number. Finally we also develop an empirical correlation of the non-dimensional fountain height Reynolds and Froude number (H/r= Re-0.72Fr2.26) by numerical regression. The result are compared with previous numerical and experimental results and found consistent.
 

Keywords: Buoyant Jet, Negatively Buoyant Jet, Fountain, Positively Buoyant Jet, Reynolds Number.

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Proceedings of the
International Conference on Mechanical Engineering 2009
(ICME2009) 26- 28 December 2009, Dhaka, Bangladesh

ICME09-FM-35

EXPERIMENTAL STUDY OF THERMALLY STRATIFIED
CO-AXIAL JETS WITH TRIP RING EXCITATION
 

M. A. T. Ali and Sukanta Bhattacharjee
Dept. of Mechanical Engineering, Bangladesh University of Engineering & Technology,
Dhaka, Bangladesh

ABSTRACT

The experimental investigation of thermally stratified coaxial jet with trip ring excitation is presented. Isothermal as well as thermally stratified or non-isothermal co-axial jet flows are developed by issuing two jets with different unidirectional velocities from a concentric compound nozzle. Enhanced mixing of coaxial free jets of different temperature and different velocity ratio is achieved with the help of vortex generation influenced by inner and outer trip ring placed around the central nozzle. The spatio-temporal velocity fields along with the temperature of the jets are studied by a pitot-static tube with an embedded thermocouple and a high-resolution pressure transducer. The inner dynamic and thermal potential core lengths become much shorter, and mixing between the inner and the outer fields is markedly enhanced by the wake produced after introducing the trip rings. Among the different combinations inner trip ring is found most efficient in mixing non-isothermal co-axial jets.
 

Keywords: Non-Isothermal, Coaxial Jets, Trip Ring, Potential Core.

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Proceedings of the
International Conference on Mechanical Engineering 2009
(ICME2009) 26- 28 December 2009, Dhaka, Bangladesh

ICME09-FM-34

MHD NATURAL CONVECTION FLOW FROM A POROUS
VERTICAL PLATE

Amena Ferdousi1and M. A. Alim2
1Department of Electronics and Electrical Engineering, Eastern University, Bangladesh
2Department of Mathematics, Bangladesh University of Engineering and Technology, Dhaka, Bangladesh.

ABSTRACT

An analysis of MHD natural convection flow from a porous vertical plate is carried out by using finite difference method together with Keller-Box scheme. This method is applied successfully to predict the surface shear stress , the rate of heat transfer, velocity and temperature profiles . The governing boundary layer equations are first transformed into a non dimensional form and the resulting non linear system of partial differential equations are then solved numerically. The numerical results of the surface shear stress in terms of skin friction coefficient and the rate of heat transfer in terms of local Nusselt number, velocity as well as temperature profiles are shown graphically and tabular form for a selection of parameters set of consisting of magnetohydrodynamic parameter M, Prandtl number Pr. MHD affects the boundary layer flow, so velocity decreases and temperature increase for this the skin friction coefficient and the rate of heat transfer decreases. Increasing value of MHD serves to thin the boundary layer.
 

Keywords: porous plate, natural convection, magnetohydrodynamic.

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Proceedings of the
International Conference on Mechanical Engineering 2009
(ICME2009) 26- 28 December 2009, Dhaka, Bangladesh

ICME09-FM-33

CONTROLLING THE SIZE DISTRIBUTION OF EXHALED
BIOAEROSOL DROPLETS BY MODULATING THE
VISCOELASTIC PROPERTIES OF HUMAN AIRWAY MUCUS

Md Anwarul Hasan1, Carlos F. Lange1 and Malcolm King2
1Department of Mechanical Engineering, University of Alberta, Canada
2Pulmonary Research Group, Department of Medicine, University of Alberta, Canada

ABSTRACT

Effect of the viscoelastic properties of artificial mucus simulant samples on the volume size distribution of bioaerosol droplets generated during simulated coughing has been investigated through in-vitro experiments. The mucus simulant samples had similar viscoelastic properties as real human airway mucus. The mucus simulant gels were prepared by mixing various proportions of 1% Locust bean gum solution and 0.1 M sodium tetraborate (XLB) solution. The viscoelastic properties of the samples were measured using a Bohlin Gemini (Malvern) nano rheometer with peltier plate assembly. An artificial cough machine was used to simulate human cough, generating aerosol droplets in a model trachea attached to the front of the cough machine. The size distribution of the droplets generated through simulated cough was measured using a laser diffraction particle sizer (Malvern SprayTec). Results confirm that the viscoelastic properties of mucus have substantial effect on the size distribution of bioaerosol droplets generated during coughing. The experimental results showed an increase in particle size as the sample changed from an elastic solid type to a viscoelastic type to viscous fluid type sample.
 

Keywords: Bioaerosol droplets, Mucus, Viscoelasticity, Surface Tension, Cough machine.

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Proceedings of the
International Conference on Mechanical Engineering 2009
(ICME2009) 26- 28 December 2009, Dhaka, Bangladesh

ICME09-FM-32

NUMERICAL STUDY ON MIXING FLOW FIELD WITH
DIFFERENT ANGLES INTO A SUPERSONIC FLOW

Rafiqul Hoque1, Mohammad Ali2 and Quamrul Islam2
1Institute of Information and Communication Technology, BUET, Dhaka, Bangladesh
2Department of Mechanical Engineering, BUET, Dhaka, Bangladesh

ABSTRACT

This paper investigates the performance of fuel combustion with the help of computer based simulation system. The simulation is carried out using huge volume of data analysis. A numerical study on mixing of hydrogen injected into a supersonic air stream has been performed by solving Two-Dimensional full Navier-Stokes equations. An explicit Harten-Yee Non-MUSCL Modified-flux-type TVD scheme has been used to solve the system of equations, and a zero-equation algebraic turbulence model to calculate the eddy iscosity coefficient. The main objectives of this study are to increase the mixing efficiency and the flame holding capability of a supersonic combustor. The performance of combustor has been investigated by varying the injection angle, keeping constant the backward-facing step height and other calculation parameters. The investigation shows that, small and large injecting angles increase the flame holding capability but mixing efficiency is poor. For moderate injecting angle, the configuration might act as a good flame holder and become efficient in mixing.
 

Keywords: Navier-Stokes Equations, Flame, Mixing Efficiency, Mach no.

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Proceedings of the
International Conference on Mechanical Engineering 2009
(ICME2009) 26- 28 December 2009, Dhaka, Bangladesh

ICME09-FM-31

EFFECTS OF RADIATION AND PRESSURE WORK ON MHD
NATURAL CONVECTION FLOW AROUND A SPHERE

M. A. Alim1 and Tahmina Akhter2
1Department of Mathematics, Bangladesh University of Engineering and Technology, Dhaka, Bangladesh
2Department of Mathematics, The University of Asia Pacific, Dhaka, Bangladesh

ABSTRACT

The effects of radiation and pressure work on magnetohydrodynamic (MHD) natural convection flow on a sphere have been investigated in this paper. The governing boundary layer equations are first transformed into a non-dimensional form and the resulting nonlinear partial differential equations are then solved numerically using finite-difference method with Keller-box scheme. We have focused our attention on the evaluation of shear stress in terms of local skin friction and rate of heat transfer in terms of local Nusselt number, velocity as well as temperature profiles. Numerical results have been shown graphically and tabular form for some selected values of parameters set consisting of radiation parameter Rd, pressure work parameter Ge, Magnetohydrodynamic parameter M and the Prandtl number Pr.
 

Keywords: Thermal Radiation, Natural Convection, Pressure Work, Magnetohydrodynamics.

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Proceedings of the
International Conference on Mechanical Engineering 2009
(ICME2009) 26- 28 December 2009, Dhaka, Bangladesh

ICME09-FM-30

EFFECT OF GAS WEBER NUMBER ON LIQUID SHEET
BREAKUP

Mohammad Ali , M. Quamrul Islam and R. Mahamud
Department of Mechanical Engineering, Bangladesh University of Engineering and Technology
Dhaka, Bangladesh

ABSTRACT

In this study dynamic behavior of liquid sheet of thermoplastic with co flowing air is discussed and numerically simulated. The Navier-Stokes systems associated with surface tension forces are solved by the Volume of Fluid (VOF) technique with a Continuum Surface Force (CSF) manner. The velocity of liquid is kept constant throughout the study whereas the velocity of air is varies which eventually varies the gas Weber number. Sulpher hexa fluoride (SF6) and high density polyethylene (HDPE) are considered as liquid to investigate the physics of breakup process. The effects of gas Weber number on liquid sheet breakup process are discussed to reveal the underlying physics of liquid disintegration. It is found that under any flow conditions a range of gas Weber number controls the instability for the breakup of liquid sheet. The pressure as well as velocity distribution of the flow field are also discussed to study the breakup processes in details.
 

Keywords: Weber Number, VOF, CSF, Sulpher Hexa Fluoride, HDPE.

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Proceedings of the
International Conference on Mechanical Engineering 2009
(ICME2009) 26- 28 December 2009, Dhaka, Bangladesh

ICME09-FM-29

MIXING OF SUPERSONIC JETS WITH DIFFERENT MERGING
ANGLES FOR CONSTANT INLET PRESSURE AND VELOCITY

Mohammad Ali, M. Quamrul Islam, TAGN Jubery and S. M. Nazrul Islam
Department of Mechanical Engineering, BUET, Dhaka, Bangladesh

ABSTRACT

In present investigation mixing of two supersonic non parallel gaseous streams has been simulated numerically. The streams are of air and hydrogen, which come into contact after passing over a finite thickness base. The gases are considered to be fed from a high-pressure reservoir. Two-dimensional unsteady state Navier-Stokes equations, energy, mass diffusion and species continuity equations are numerically simulated to analyze two-dimensional shear layers in supersonic flow field. An explicit Harten-Yee Non-MUSCL Modified flux-type TVD (total variation diminishing) scheme has been used to solve the system of equations. An algebraic turbulence model was used to calculate the eddy viscosity coefficient. Keeping constant the inlet pressure and velocity of the streams, the merging angle is varied to observe the physics of the mixing flow fields, mixing of shear layers and mixing efficiency. The result shows that when merging angle increases interaction between two streams increases and high momentum exchange occurs and eventually high mixing occurs for the pressure ratios considered here.
 

Keywords: Supersonic Combustor, Mixing, Shear Layers, Merging Angle

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Proceedings of the
International Conference on Mechanical Engineering 2009
(ICME2009) 26- 28 December 2009, Dhaka, Bangladesh

ICME09-FM-28

A MODIFIED EULERIAN-LAGRANGIAN APPROACH FOR
SOLVING MULTI-PHASE FLOW APPLIED TO A COMPACT
DOWN-HOLE SUB-SEA GAS-LIQUID SEPATATOR

Shakil Ahmed1, Gerardo Sanchez Soto1, Jamal Naser2 and Edson Nakagawa1
1CSIRO Earth Science and Resource Engineering, Technology Park Kensington, Perth
2School of Engineering and Industrial Sciences, Swinburne University of Technology, Hawthorn,
Melbourne

ABSTRACT

This paper presents a modified Eulerian-Lagrangian approach for solving multi-phase flow applied to a laboratory scale gas-liquid separator designed for high gas content. The separator consists of two concentric pipes with swirl tube in the annular space between the pipes. The gas-liquid mixture comes from the tangential side inlet and the system works with a combination of gravity and centrifugal forces to achieve a high-efficient gas-liquid separation. In the modified Eulerian-Lagrangian method, gas flow is coupled with the spray and wall film models. Spray model involves multi-phase flow phenomena and requires the numerical solution of conservation equations for the gas and the liquid phase simultaneously. With respect to the liquids phase, discrete droplet method (DDM) is used. The droplet-gas momentum exchange, droplet coalesces and breaks-up, droplet-wall interaction with wall-film generation and entrainment of the water droplet back into the gas stream are taken into account in this investigation. To be consistent with the experiments the same air water mixture is used for the present work. The standard k-ε turbulence model is used for turbulence closure. The predicted results from the modified Eulerian-Lagrangian multi-phase model explain the complex flow behavior inside the separator and are in good agreement when compared with experiments.
 

Keywords: Modified Eulerian-Lagrangian Approach, Compact Gas-liquid Separator, Multi-Phase Flow.

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Proceedings of the
International Conference on Mechanical Engineering 2009
(ICME2009) 26- 28 December 2009, Dhaka, Bangladesh

ICME09-FM-27

 

AERODYNAMICS OF VEHICLE ADD-ONS

Firoz Alam, Harun Chowdhury and Simon Watkins
School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University,
Melbourne, Australia

ABSTRACT

Over 80% of the required total vehicle power is essential to overcome the aerodynamic drag and the remaining power is used for rolling resistance. An aerodynamically streamlined shape significantly reduces the aerodynamic drag thus lowering the fuel consumption. Although aerodynamics of road vehicles has been well studied, scant studies on aerodynamic effects of vehicle add-ons were reported to the public domain. Due to the life style demands, most modern passenger cars use various add-ons including roof-rack ski-rack, bicycle rack, advertising signboard, police and ambulance siren, and portable ladder. The aerodynamic impact on fuel consumption was not well studied, fully understood and quantified. Therefore, the primary objectives of this study were to experimentally measure the aerodynamic drag generated by the use of various vehicle add-ons under a range of vehicle operating speeds and cross winds conditions. The study was conducted using a reduced scale (25%) detailed model of a production large family size passenger car manufactured in Australia. The aerodynamic drag coefficient was related to fuel consumption and a detailed analysis of fuel consumption was conducted.
 

Keywords: Vehicle Aerodynamics, Wind Tunnel, Drag Coefficient, Vehicle Add-ons.

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Proceedings of the
International Conference on Mechanical Engineering 2009
(ICME2009) 26-28 December 2009, Dhaka, Bangladesh

ICME09-FM-26

CHARACTERISTICS OF TWIN AXISYMMETRIC FREE JETS

Mohammed A. Azim
Department of Mechanical Engineering, Bangladesh University of Engineering and Technology
Dhaka, Bangladesh

ABSTRACT

Axisymmetric single free jet and twin identical free jets with three nozzle spacing have been investigated numerically. Flow characteristics of single jet, twin jets and two superimposed individual jets are compared, and effect of nozzle spacing on twin jet flows is studied. Turbulence closure in those jet flows was achieved by one equation model. The governing equations were solved by using Implicit θ -Scheme and Tridiagonal Matrix Algorithm. Mean motion augmentation and turbulence attenuation occur on the axis of symmetry of twin jets compare to single jet and two superimposed individual jets. Both converging and combining points of twin jets are found to move downstream with the increase in nozzle spacing. It also appears that increase in nozzle spacing is associated with mean motion attenuation and turbulence augmentation at any axial location of the flows between the nozzle centerlines.

Keywords: Axisymmetric Twin Jets, Numerical Study, Vortex Breakdown.

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Proceedings of the
International Conference on Mechanical Engineering 2009
(ICME2009) 26- 28 December 2009, Dhaka, Bangladesh

ICME09-FM-25

AN EXPERIMENTAL INVESTIGATION OF THE EFFECT OF
VEHICLE SPACING ON BOUNDARY LAYER
CHARACTERISTICS IN THE 2-VEHICLES PLATOON
 

A.Motin and M.A.T. Ali
Department of Mechanical Engineering, Bangladesh University of Engineering and Technology, Dhaka,
Bangladesh.

ABSTRACT

Aerodynamic shape of a moving object is a major concern of the researchers from many years. Though different accessories, engine parts and passenger compartment for example in the moving vehicle are needed to be available, perfect aerodynamic shape of any body, like passenger car, is not possible to maintain. In this circumstance, alternate factor other than body shape which can affects the vehicle performance is required to keep in consideration. For this, aerodynamic characteristics of two vehicles moving in platoon maneuver are investigated as the function of vehicle spacing (space between two vehicles) in this study. To conduct this investigation, 1/32 scale models of a saloon car are tested in the 300x300 mm wind tunnel facility of the Department of Mechanical Engineering, BUET. Velocities in the vertical plane through the centre of the wind tunnel are measured by pitot static tube which is interfaced with a computer through pressure transducer for data acquisition and is traversed by a computer controlled 3-axes co-ordinate positioning device. The integral analysis of the boundary layer is used to quantify the behavior of the aerodynamic characteristics and the effects of vehicle spacing on the boundary layer characteristics and skin friction. The zone of flow separation approaching laminar-turbulent transition is also investigated. In this study the displacement and momentum thicknesses on the trailing vehicle are found to be higher for smaller vehicle spacing. The flow strikes the front of the vehicle and is accelerated over the bonnet and is observed to be separated from the rear zone of the bonnet but reattaches in the leading edge of the roof. The flow reattachment becomes little bit earlier in the trailing vehicle than that in the leading vehicle.
 

Keywords: Boundary Layer, Flow Separation, Platoon Vehicle, Friction Drag, Friction Coefficient.

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Proceedings of the
International Conference on Mechanical Engineering 2009
(ICME2009) 26- 28 December 2009, Dhaka, Bangladesh

ICME09-FM-24

EFFECT OF A HEATED HOLLOW CYLINDER ON COMBINED
FREE AND FORCED CONVECTION IN A VENTILATED CAVITY
 

M. M. Rahman, M. A. Alim and M. A. H. Khan
Department of Mathematics, Bangladesh University of Engineering and Technology (BUET),
Dhaka, Bangladesh

ABSTRACT

Effect of a heated hollow cylinder on combined free and forced convection in a ventilated cavity is studied numerically. The wall of the cavity is assumed to be adiabatic. Flows are imposed at the bottom of the left wall and exited at the top of the right wall of the cavity. The heated cylinder is placed at the center of the cavity. The present study simulates a practical system such as an air-cooled electronic equipment with a heat component or an oven with heater. Emphasis is sited on the influences of the cylinder diameter and thermal conductivity of the cylinder in the cavity. The consequent mathematical model is governed by the coupled equations of mass, momentum and energy and is solved by employing Galerkin weighted residual method of finite element formulation. A wide range of pertinent parameters such as Reynolds number, Richardson number, cylinder diameter and the solid-fluid thermal conductivity ratio are considered in the present study. Various results such as the streamlines, isotherms, heat transfer rates in terms of the average Nusselt number and average fluid temperature in the cavity are presented for different parameter. It is observed that the cylinder diameter has significant effect on both the flow and thermal fields but the solid-fluid thermal conductivity ratio has insignificant effect on the flow field.
 

Keywords: Hollow Cylinder, Ventilated Cavity, Combined Free And Forced Convection.

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Proceedings of the
International Conference on Mechanical Engineering 2009
(ICME2009) 26- 28 December 2009, Dhaka, Bangladesh

ICME09-FM-23

AERODYNAMICS OF FOOTBALLS

Firoz Alam, Harun Chowdhury, Christopher Whyte and Aleksandar Subic
School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University, Australia

ABSTRACT

Ball sports are becoming faster and more demanding than ever before, pushing traditional ball designs to their limits. In order to meet the increasing performance requirements, the ball manufacturers are producing new designs that can display better aerodynamic performance, geometric symmetry and balance. Since the inception of football game-the most popular and widely played game in the world, the centre piece of the game- the spherical ball which has gone through significant structural changes over the decades. A traditional spherical ball made of 32 leather panels stitched together in 1970s has now become only 14 synthetic curved panels thermally bonded (without stitches). Currently Adidas, the official supplier and manufacturer of footballs to FIFA is believed to be more spherical and it performs more uniformly regardless of where it is hit. Therefore, the primary objectives of this study were to evaluate aerodynamic performances of a current Adidas 14 curved panel football ball and a traditional Nike made 32 leather panels football ball. The aerodynamic forces and moments were measured experimentally for a range of wind speeds (20 km/h to 130 km/h) and the non-dimensional drag coefficient was determined and compared
 

Keywords: Aerodynamics, Football, Wind Tunnel, Drag Coefficient.

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Proceedings of the
International Conference on Mechanical Engineering 2009
(ICME2009) 26- 28 December 2009, Dhaka, Bangladesh

ICME09-FM-22

STENOSIS LENGTH AND ITS IMPACT ON FLOW OF BLOOD
THROUGH RECTANGULAR STENOSED CORONARY ARTERY

S. Chakrabarti1 and D. K. Mandal2
1Dept. of Mech. Engg., Bengal Engineering and Science University, Shibpur, India
2Dept. of Basic Science & Humanities, College of Engg. & Management, Kolaghat, India

ABSTRACT

Impact of stenosis length on flow of blood through rectangular stenosed coronary artery has been investigated in case of non dimension stenosis lengths of 0.1, 0.5, 1.0 and 2.0 for the restriction of 50% (by diameter) and Reynolds number of 200. Effect on streamline contour and wall shear stress has been discussed and presented along with its possible physiological aspects. It is revealed that the wall shear stress is dependent upon the stenosis length but reattachment length is relatively independent of stenosis length.
 

Keywords: Stenosis, Wall pressure, Wall Shear Stress, Stenosis Length

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Proceedings of the
International Conference on Mechanical Engineering 2009
(ICME2009) 26- 28 December 2009, Dhaka, Bangladesh

ICME09-FM-21

REDISTRIBUTED GAS EXCHANGE MECHANISM IN HUMAN
LUNG’S PERIPHERALS

M. U. Ahmmed, H. Hirahara and T. Yamamoto
Graduate School of Science and Engineering,
Saitama University, Shimo-Okubo, Sakura, Saitama,338-8570, Japan

ABSTRACT

The velocity distribution was investigated with particle image velocimetry (PIV) in a real size model of human’s lung peripherals. The working gas is air and the oil mist was used as a tracer. The unsteady velocity profile was obtained with phase locked image capturing, and the data was processed in statistically. The target region of this study is between the 18th to 20th bifurcations in lung’s airway. The fundamental respiratory flow was investigated in the present experiment under the high frequency oscillatory ventilation (HFOV) mode for the different compliance conditions, which is important for the clinical treatment. According to the mean flow analysis, the phase delay was estimated theoretically and obtained experimentally. The phase delay in the mean flow was very small, however the obvious flow mixing was observed in the air path lines.

Keywords: Human lung, PIV, Compliance, HFOV, Redistribution of Gas.

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Proceedings of the
International Conference on Mechanical Engineering 2009
(ICME2009) 26- 28 December 2009, Dhaka, Bangladesh

ICME09-FM-20

AERODYNAMICS OF TEXTILES FOR ELITE CYCLIST

Harun Chowdhury1, Firoz Alam1, David Mainwaring2, Jordi Beneyto-Ferre2, Margaret Tate2,
Dorothy Forster2 and Aleksandar Subic1
1School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University, Australia
2School of Applied Sciences, RMIT University, Melbourne, Australia

ABSTRACT

Aerodynamic properties play a significant role in the textiles across a wide range of sports including cycling, skiing, bobsleigh, and speed skating. Considerations in this aerodynamic performance include the textile weave or knit, seam and fastener placement and air permeability. Elite competition usually involves very short winning time margins in events that often have much longer timescales, making aerodynamic resistance and its associated energy loss during the event significant in the outcome. In fact, a two fold increase in athlete velocity results in a fourfold increase in the drag force needing to be overcome. This paper describes the impact of textile surface employing a standard cylindrical arrangement in wind tunnel studies to provide precise data on aerodynamic drag and lift as a function of athlete’s body positions together with garment seam placement and apply these optimized data to cycling apparel design for elite cyclist.
 

Keywords: Wind Tunnel Testing, Drag, Lift, Aerodynamic, Cycling, Fabric.

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Proceedings of the
International Conference on Mechanical Engineering 2009
(ICME2009) 26- 28 December 2009, Dhaka, Bangladesh

ICME09-FM-19

PERFORMANCE OF A CIRCULAR ARC HORIZONTAL AXIS WIND
TURBINE

Sayeda Nazma Yeasmin and M. Quamrul Islam
Atlas Bangladesh Limited, BSEC, Tongi, Gazipur
Department of Mechanical Engineering, BUET, Dhaka-1000, Bangladesh

ABSTRACT

An experimental investigation and design analysis of a Horizontal Axis Wind Turbine with arched steel plate section has been performed. Wind characteristics of different regions of Bangladesh have been analyzed and hence, a compatible design of Horizontal Axis Wind Turbine applicable to the pump has been carried out. Performance of the wind turbine models with circular arc blade section for different number of identical blades have been studied at constant wind velocity. The theoretical analysis has been done using momentum theory and Blade element theory. It is observed that the calculated results of the wind turbine with circular arc blade profile are comparable with those of the turbine with airfoil blade section. An extensive experimental investigation of the performance of the designed wind turbine model has been conducted in the wind tunnel. The wind turbines with 2, 3, 4, 5 and 6 blades for linearized chord and twist angle have been considered. The experimental investigation was performed for each turbine at various blade pitching and at different wind velocities. Finally, the calculated results of the wind turbine have been compared with the existing experimental results. It is observed that there are good agreements between the present experimental result and the existing other experimental results.

Keywords: Horizontal Axis Wind Turbine, Circular Arc Blade, Power Coefficient, Pitching Angle.

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Proceedings of the
International Conference on Mechanical Engineering 2009
(ICME2009) 26- 28 December 2009, Dhaka, Bangladesh

ICME2009-FM-18

FUZZY LOGIC APPROACH FOR PREDICTION THE LIFT
COEFFICIENT OF AN AIRCRAFT MODEL WITH AND WITHOUT
WINGLET

A. Hossain1,2, A. Rahman2, A.K.M Mohiuddin2, A.K.M.P. Iqbal1, M. Arifin1, M. Mazian1
1 Department of Mechanical Engineering, Faculty of Engineering, University Industry Selangor, Malaysia
2Department of Mechanical Engineering, Kulliyyah of Engineering, International Islamic University
Malaysia

ABSTRACT

This paper describes the unique structure of an aircraft model with and without winglet tested at Aerodynamics Laboratory, Faculty of Engineering (University Putra Malaysia) using subsonic wind tunnel of 1000 mm × 1000 mm rectangular test section and 2500 mm long. Focusing on predicting the aerodynamic characteristics of the aircraft model, three main issues are studied in this paper. First, a six component wind tunnel external balance is used for measuring lift, drag and pitching moment. Secondly, Tests are conducted on the aircraft model with and without winglet. And thirdly, Artificial intelligence system such as fuzzy logic approach is used to predict the lift coefficient performance. Therefore, the primary purpose of this work was to investigate the relationship between lift coefficients, with free-stream velocities and angle of attacks, and to illustrate how fuzzy system might play an important role in prediction of lift coefficient with the addition of certain winglet configurations.

Keywords: Winglet, External Balance, Lift Coefficient, Fuzzy Logic.

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Proceedings of the
International Conference on Mechanical Engineering 2009
(ICME2009) 26- 28 December 2009, Dhaka, Bangladesh

ICME09-FM-17

A STUDY OF BADMINTON SHUTTLECOCK AERODYNAMICS

Firoz Alam, Harun Chowdhury, C. Theppadungporn and Aleksandar Subic
School of Aerospace, Mechanical and Manufacturing Engineering,

ABSTRACT

Being a bluff body, the shuttlecock generates significant aerodynamic drag and complex flight trajectory. Despite the popularity of the game, scant knowledge is available in the public domain about the aerodynamics of shuttlecocks. The primary objectives of this study were to experimentally measure the aerodynamic properties of a series of natural feather and synthetic shuttlecocks under a range of wind speeds and pitch angles. The drag coefficients for shuttlecocks were determined and compared. The natural feather shuttlecock indicated lower drag coefficient at low speeds and significantly high value at high speeds. On the other hand, the synthetic shuttlecocks have shown opposite trends. The average drag coefficient for shuttlecocks found in this study was between 0.5 and 0.6.
 

Keywords: Aerodynamics, Shuttlecock, Wind Tunnel, Drag Coefficient.

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Proceedings of the
International Conference on Mechanical Engineering 2009
(ICME2009) 26- 28 December 2009, Dhaka, Bangladesh

ICME09-FM-16

FLOW CHARACTERISTICS THROUGH A ROTATING CURVED
DUCT WITH SQUARE CROSS SECTION

R. N. Mondal, A. K. Datta, M. A. Ali and M. S. Uddin
Mathematics Discipline; Science, Engineering and Technology School,
Khulna University, Khulna, Bangladesh

ABSTRACT

In this paper, a comprehensive numerical study is presented for the thermal flow through a rotating curved duct with square cross section. Numerical calculations are carried out over a wide range of the Taylor number 0 ≤ Tr ≤ 3000 for the Dean numbers Dn =1000 and Dn = 2000 with the Grashof numberGr = 500, where the outer wall is heated and the inner one cooled. Spectral method is used as a basic tool to solve the system of non-linear differential equations. The rotation of the duct about the center of curvature is imposed, and the effects of rotation (Coriolis force) on the flow characteristics are investigated. As a result, multiple branches of asymmetric steady solutions with two- and four-vortex solutions are obtained. Linear stability of the steady solutions is then investigated. When there is no stable steady solution, time evolution calculations of the unsteady solutions are obtained, and it is found that there occur only periodic and multi-periodic solutions where the solution is unstable.

 Keywords: Curved Square Duct, Secondary Flow, Steady Solutions, Dean Number, Taylor Number.

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Proceedings of the
International Conference on Mechanical Engineering 2009
(ICME2009) 26- 28 December 2009, Dhaka, Bangladesh
 

ICME09-FM-15

FLOW THROUGH A CURVED RECTANGULAR DUCT
 

R. Nath Mondal, B. Roy and A. Kumar Datta
Mathematics Discipline; Science, Engineering and Technology School,
Khulna University, Khulna, Bangladesh

ABSTRACT

Flow through a curved rectangular duct of aspect ratios 0.5 ≤ l ≤ 1.5 is investigated numerically by using a spectral and covering a wide range of the Dean number. First, bifurcation structure of the steady solutions is investigated. As a result, a number of steady solution branches with asymmetric two-vortex and symmetric two- and multi-vortex solutions are obtained. The main concern of the present study is to investigate the transitional behavior of the unsteady solutions such as periodic, multi-periodic and chaotic solutions, as the aspect ratio changes. Time evolution calculations as well as their phase spaces show that the steady flow turns into chaotic flow through periodic and multi-periodic flows, if the Dean number is increased no matter what the aspect ratio is. It is found that the flow oscillates periodically or aperiodically between two-, four-, six-, eight- and ten-vortex solutions, as the aspect ratio is increased. It is also found that the axial flow shifted at the outer wall of the duct as the Dean number is increased.
 

Keywords: Curved Duct, Secondary Flow, Time Evolution, Periodic Solution, Chaos.

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Proceedings of the
International Conference on Mechanical Engineering 2009
(ICME2009) 26- 28 December 2009, Dhaka, Bangladesh

ICME09-FM-14

ENTRANCE FLOW THROUGH ROTATING CURVED PIPE OF
CIRCULAR CROSS-SECTION

M. A. Masud and M. Mahmud Alam
Mathematics Discipline, Khulna University, Khulna, Bangladesh

ABSTRACT

A numerical study is performed regarding entrance flow of a viscous incompressible fluid through rotating curved pipe of circular cross-section. The flow depends on the pressure gradient force, centrifugal force due to curvature and coriolis force due to rotation. The effects of all these forces result in interesting flow behaviours in the entry region which are analyzed in the present study. The mathematical model is established considering three dimensional momentum equation. The problem is solved by finite difference method in a computational mesh extending from the inlet immediately adjacent to the reservoir to the fully developed region.
 

Keywords: Entry Flow, Rotation, Curved Pipe.

 

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Proceedings of the
International Conference on Mechanical Engineering 2009
(ICME2009) 26- 28 December 2009, Dhaka, Bangladesh
 

ICME09-FM-13

COMBINED EFFECTS OF CURVATURE AND TORSION ON
FLUID FLOW IN A HELICAL RECTANGULAR DUCT
 

P. Kumar Bhattacharjee1 and M. Mahmud Alam2
1Natural Science Group, National University, Gazipur, Bangladesh
2Mathematics Discipline, Khulna University, Khulna, Bangladesh

ABSTRACT

This paper is concerned with the steady incompressible fully developed flow through a left-handed helical rectangular duct and presents the flow structure for various Dean number( ) n D , non-dimensional torsion (τ ′) and non-dimensional curvature (κ ′) at aspect ratio γ = 1.5 . Numerical study is performed to investigate the flow characteristics under various flow conditions. The flow structure in the helical rectangular duct is investigated numerically to examine the combined effects of non-dimensional curvature and torsion. Spectral method is used as a main tool for numerical calculations, where the Chebyshev polynomial, the collocation methods, the Arc-length method and the Newton-Raphson method are also used as secondary tools.
 

Keywords: Curvature, Torsion, Rectangular Duct.

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Proceedings of the
International Conference on Mechanical Engineering 2009
(ICME2009) 26- 28 December 2009, Dhaka, Bangladesh
 

ICME09-FM-12

NUMERICAL SIMULATIONS OF SUPERSONIC MICRO JETS
 

A. M. M. Ashraful1, A. M. Mahabubul2, Matsuo Shigeru3, Setoguchi Toshiaki4 and K. Heuy Dong5
1Graduate School of Science & Engineering, Saga University, Saga, Japan.
2Department of Mechanical Engineering, Chittagong University of Engineering & Technology,
Chittagong, Bangladesh.
3Department of Mechanical Engineering, Saga University, Saga, Japan.
4Institute of Ocean Energy, Saga University, Saga, Japan.
5School of Mechanical Engineering, Andong National University, Andong, Korea

ABSTRACT

Supersonic microjets acquire considerable research interest from a fundamental fluid dynamics perspective in part because the combination of highly compressible flow at low-to-moderate Reynolds number is not very common, and in part due to the complex nature of the flow itself. In addition, microjets have a great variety engineering applications such as micro-propulsion, MEMS (Micro-Electro Mechanical Systems) components, microjet actuators and fine particle deposition and removal. Numerical simulations have been carried out at moderate nozzle pressure ratios and for different nozzle exit diameters to investigate and to understand in-depth of aerodynamic characteristics of supersonic microjets.
 

Keywords: Compressible, Microjets, Supersonic, Jet structure, Numerical simulation.

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Proceedings of the
International Conference on Mechanical Engineering 2009
(ICME2009) 26- 28 December 2009, Dhaka, Bangladesh
 

ICME09-FM-11

NUMERICAL SIMULATION OF A CONFINED LAMINAR
DIFFUSION FLAME WITH VARIABLE PROPERTY
FORMULATION

B. K. MANDAL 1, A.K. CHOWDHURI 1 and A. J. BHOWAL 2
1Bengal Engineering and Science University, Howrah, India
2Heritage Institute of Technology, Kolkata, India

ABSTRACT

A numerical model is used for simulation of a confined axisymmetric laminar jet diffusion flame under normal gravity and pressure conditions to predict the velocity, temperature and species distributions. An explicit finite difference technique has been adopted for the numerical simulation of reacting flow with finite rate chemistry and variable thermodynamic and transport properties. The predictions match well with the experimental results available in the literature. A recirculation of ambient air is observed to extend from the exit plane into the domain adjacent to the wall. Radial velocity is never positive (away from the axis) in the solution domain. High temperature and high CO2 concentration zone are confined to a small radial distance.
 

Keywords: Diffusion flame, Recirculation, Temperature distribution.

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Proceedings of the
International Conference on Mechanical Engineering 2009
(ICME2009) 26- 28 December 2009, Dhaka, Bangladesh
 

ICME09-FM-10

INDUCED DRAG REDUCTION FOR MODERN AIRCRAFT
WITHOUT INCREASING THE SPAN OF THE WING BY USING
WINGLET

Mohammad Mashud, Md. Hasan Ali, Abdullah-Al-Nahian and S. M. S. Selim
Department of Mechanical Engineering
Khulna University of Engineering & Technology, Khulna

ABSTRACT

This paper describes the potential of winglets for the reduction of induced drag without increasing the span of the aircraft. For this experiment a model aircraft has been constructed by aluminum-alloy whose wings profile is NACA 4315. There are three different types (rectangular, triangular and circular) of winglet are constructed for experiment. Aerodynamic characteristics for the model aircraft wing with rectangular, triangular and circular winglets and without winglet have been studied using a subsonic wind tunnel of 36cm×36cm rectangular test section. Drag measurements are carried out using an external balance. Tests are carried out on the aircraft model with and without winglet at the Reynolds numbers 0.16×106, 0.18×106, 0.20×106, 0.23×106 and 0.25×106. The experimental results show that the drag decreases by 26.4% - 30.9% as compared to the aircraft model with and without winglet for the maximum Reynolds number considered in the present study.

 

Keywords: Induced Drag, Wing, Winglet, Aircraft and Aerodynamics.

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 Proceedings of the

International Conference on Mechanical Engineering 2009
(ICME2009) 26- 28 December 2009, Dhaka, Bangladesh
ICME09-FM-09

A COMPUTATIONAL STUDY OF TRANSONIC MOIST AIR FLOW
AROUND A SYMMETRIC DISK BUTTERFLY VALVE

A. B. M. Toufique Hasan1, Mohammad Mamun2, Shigeru Matsuo3 and Toshiaki Setoguchi4
1 Graduate School of Science and Engineering, Saga University, Saga, Japan
2 Department of Mechanical Engineering, Bangladesh University of Engineering and Technology, Dhaka ,
Bangladesh
3Department of Mechanical Engineering, Saga University, Saga, Japan
4 Institute of Ocean Energy, Saga University, Saga, Japan

ABSTRACT

Transonic flow around a symmetric disk butterfly valve is associated with the appearance of shock waves standing on valve surfaces. In this case, the interaction between shock wave and boundary layer becomes complex and thus generates the flow induced aerodynamic instability. In the transonic or supersonic flow where vapour is contained in the main flow, the rapid expansion of the flow may give rise to non-equilibrium condensation. In the present study, the effect of non-equilibrium condensation of moist air on the shock induced flow field oscillation around a butterfly valve was investigated numerically. The results showed that in case with non-equilibrium condensation, the flow field aerodynamic instabilities such as root mean square of pressure oscillation and shock induced oscillation frequency are reduced significantly compared with those without the non-equilibrium condensation. Moreover, the total pressure loss increases and the vortex shedding frequency is reduced with non-equilibrium condensat

Keywords: Transonic Flow, Shock Induced Oscillation, Moist Air.

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