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Home>Products>Journal and Reviews>I.RE.M.E.>Latest issue
International Review of Mechanical Engineering - May 2010 - Papers
International Review of Mechanical Engineering - Papers
Abstract - The turbulent heat transfer and fluid flow in a bidimensional planar corrugated channel are numerically analyzed for constant fluid properties and no phase change. The walls of the channel are submitted to a constant heat flux. Numerical solutions are obtained by using the finite volume method for different Reynolds numbers (varying between 1000 and 4000), for which the flow is known experimentally to be turbulent. It was found that both Nusselt numbers and friction coefficient are affected by the Reynolds number and the aspect ratio H/P. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Forced Convection, corrugated Channel, Finite Volumes.
Abstract - The present work consists of the modilisation of the natural convection in streamline flow in a room heated by the technique of a ventilated Trombe wall adapted to the site of the town of Bechar (south-west of Algeria), one typical winter day. The equations governing the movement of air and the heat transfer inside the room are solved numerically using one of codes CFD ”Fluent”. The influence of the variation depth of the solar chimney on the thermal efficiency of the system was studied. The principle of functioning of the system is visualized. The temperatures obtained on the level of the zone of occupation are adaptable to the interval of thermal comfort. The results of simulation are congruent with those of the literature. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Natural Convection, Heating Passive, Solar Energy, Numerical Modeling, Trombe Wall.
Abstract -
Convection heat transfer and pressure drop is investigated experimentally,
for the flow of dilute polymer solutions (polyacrylamide) inside
multi-channels flat tube and compared with water. An experimental
apparatus equipped with the required measuring devices was designed and
constructed to assess the effects of the operating parameters on
convection heat transfer and pressure drop. The flat Aluminum
multi-channels extruded tube composed of 22 parallel rectangular
mini-channels (3.6 mm × 3.85 mm) with hydraulic diameter of 3.72 mm.
Different polymer concentrations are considered; 10, 20, 50 and 100 ppm.
This work covers a range of Reynolds number from 300 to 1200 and heat
flux from 15 to 41 kW/m2. The experimental measurements for
temperature, pressure, and pressure drop and flow rate are taken to
perform the required analysis. Therefore, the average value of
convection heat transfer coefficient and friction factor for different
operating parameters are computed. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved Keywords: Mini-channels, Flat tube, Convection heat transfer, Polymer solutions.
Abstract - The semidiscretise Method of Lines (MOL) is used for the numerical analysis of transient phenomena occurring during the operation of natural gas pipelines and pipe networks. The Method of Lines discretises the spatial terms of the governing equations, reducing the partial to an ordinary differential equations system which can be solved by various techniques. For comparison and validation purposes, transient phenomena are also simulated here by means of the Method of Characteristics (MOC) which is a reliable but rather old method. The governing equations system is based on the fundamental conservation laws of mass, momentum, and energy for the unsteady one dimensional compressible pipe flow. Experimental results representing realistic transient pipeline phenomena have been obtained from the laboratory test facility. The agreement between numerical results of both methods and measurements is satisfactory especially when experimental data are introduced as time dependent boundary conditions. In addition the Method of Lines proved efficient and applicable to rapid as well as to slow transients which is a very common unsteady behaviour of natural gas pipeline flows. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Method of Lines, Method of Characteristics, Numerical Simulation, Natural Gas, Pipeline Flow.
Abstract - Flow over forward facing step (FFS) has been taken as a useful prototype to investigate characteristics of separated flow with heat transfer. But to date, the entropy generation analysis in the forced convective flow over FFS is absent yet although there are many researches about numerical analysis of this type of flow from fluid mechanic and heat transfer points of view. The present work investigates the entropy generation in a laminar forced convection flow over a forward-facing step in a duct. The entropy generation is due to heat transfer and fluid flow in forced convection laminar flow. Heat transfer takes place by temperature different between inlet fluid and isotherm solid surfaces. Momentum and energy equations are solved numerically in the Cartesian coordinate system using the SIMPLE algorithm. Numerical expressions in terms of entropy generation number (Ns) and Nusselt number (Nu) are derived in dimensionless form using velocity and temperature profiles. Comparison between the present numerical results with the theoretical findings by other investigator about entropy generation in convection flow over backward facing step shows a good consistency. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Forward Facing Step, Laminar Convection Flow, Entropy Generation.
Abstract - This study was conducted to investigate the potential of coconut coir fiber as sound absorber. To improve their acoustical characteristic in low frequencies, porous layer were used in the front and back as facing. Effects of porous layer facing on sound absorption coefficient of sound absorber using coconut coir fiber were studied. Non-woven cotton cloth was the type of porous layer that were used as facing for coconut coir fiber, which have been used widely in automotive industry. The samples were tested at the acoustic lab of the Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, according to ASTM E 1050-98 international standards for noise absorption coefficient. The experimental data obtained indicate that porous layer facing can improve noise properties at low and high frequencies with significant increased in noise absorption coefficient index. The data presented shows that facing with porous layer in the front coconut coir fiber sound absorber is better than facing at the back. Twenty millimeter thick layer coconut coir fiber facing with porous layer in the front exhibits peak value at frequency 2750 Hz – 2825 Hz with maximum value of 0.97. The good agreement was obtained from experimental and analysis results using equivalent electrical circuit approach. This indicated that the equivalent electrical circuit approach can be used to design and optimize the acoustic characteristic coir fiber as sound absorber. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Coconut Coir Fiber, Porous Layer, Noise Absorption, the Equivalent Electrical Circuit Approach.
Abstract - Prediction of the tool wear apriori to the machining process is vital to optimize the manufacturing cycle in terms of selecting the proper tool grade and cutting parameters. This will ultimately lead to a low cost and high efficiency manufacturing cycle. In the present work, artificial intelligence schemes are used to predict flank wear progression in turning operations. Experiments have been conducted on particulate metal matrix composites (MMCs), consisting of aluminum matrix reinforced with alumina (Al2O3) particles with alumina volume fractions of: 10% and 20%. The process parameter conditions: cutting speed, feed-rate, depth of cut, and machining time are used as inputs to the artificial neural networks (ANN) models. ANN models were validated by predicting the tool wear for a given set of cutting parameters that falls within the range or alternatively by predicting the tool wear value at a specific machining time at the same cutting condition. The ANN prediction and the experimental data were found to be in reasonable agreement. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Machining, Metal Matrix Composites, Neural Networks, Tool Wear.
Abstract -
Characteristics of rotating stall in a radial vaneless diffuser model were
investigated experimentally. The maximum number of rotating stall cells
found in this study was two. The single-stall cell structure was found
to be dominant over the two-stall cell structure at flow coefficients
much lower than the critical flow coefficient. The angular speeds of
stall cells increase linearly with the impeller speed and it decreases
with the increase of the diameter ratio. On the other hand, the effect
of diffuser width ratio on the pressure pattern frequency is
insignificant; therefore, it is not presented.
Keywords: Rotating Stall, Centrifugal Compressor, Vaneless Diffuser.
Abstract -
The present work investigates the heat-aging effects on the hardness and
tensile properties of vulcanized natural rubber using dumb-bell test
specimens under uniaxial loading. The material used was a vulcanized
natural rubber with a typical engine mount rubber formulation and an
International Rubber Hardness Degree of 60. The test specimens were aged
at two different temperatures 70°C and 100°C for times ranging from 5 to
168 hours. Tensile measurements were done to study the effects of aging
on stress-strain properties. The result of this study was indicated that
the hardness increases as the heat-aging temperature or heat-aging
period increase. The tensile strength and elongation at break decrease
as the heat-aging temperature or period increase. Also, the modulus at
100% increases as hardness increase. The rate of decrease of tensile
strength and elongation at break is higher at 100°C heat-aging condition.
Keywords: Rubber, Tensile Properties, Hardness, Heat-Aging Effects.
Abstract -
Numerical simulation of the infrared (IR) emissions from exhaust plumes
originating from geometrically simple nozzles, namely, a conventional
circular, a rectangular, and lobed, have been carried out in order to
preliminarily study the IR characteristics of full-scale plumes of
different mixing behaviour. For all exhaust flows investigated, the
turbulent jet was considered to be similar in temperature and species
concentrations to exhaust from a turbojet engine. The IR emission from
the jets was simulated in the IR region between 2 and 8 µm by
application of the narrowband model with the assumption of absence of
the soot particles. The emission from the rectangular plume is sensitive
to the direction of observation, namely vertical and horizontal, that is
in agreement with data known from literature. The sensitivity of the
lobed plume emission to the direction of observation is however found to
be negligible. When compared with the baseline circular plume, the
rectangular plume emits by 20% less whereas the lobed one emits by 17 %
less for the conditions investigated.
Keywords: IR Signature, IR Signature Reduction, Thermal Radiation, Turbulent Jet.
Abstract
- In this paper, the analysis of natural frequencies for all clamped
edges rectangular flexible thin plate is carried out using Finite
Difference (FD) and Finite Element (FE) approaches. According to the
literatures, the differential equation of plate was obtained by
considering the Kirchhoff hypotheses and Newton’s law. The dynamic
differential model is developed by using the FD to obtain the natural
frequencies of given plate; for this purpose, a displacement model is
converted to combination of sine and cosine functions in form of Fast
Fourier Series. In second method, modes of vibration are driven by FE
method using the ABAQUS software. The obtained natural frequencies of
both methods are evaluated and compared with previous literatures; the
outcomes can explain that the improved FD method’s results are more
accurate in compare with FE method’s.
Keywords: Flexible Rectangular Plate, Natural Frequency, Finite Difference Method, Finite Element Method.
Abstract -
ADC 12, ADC 1 and HT 1 die cast aluminums mainly differ in their
composition of silicon. The shape of silicon particles had made a
difference in term of improving strength, elasticity, corrosion
resistance and promotes large grain sizes which causes increasing
magnetic permeability, and presumably corrosion. In this research, the
effect of the silicon composition on the corrosion behavior was
investigated. Through immersion corrosion test for the period of 28
days, the corrosion behavior of die-cast ADC 1, ADC 12 and HT 1 aluminum
alloys had been determined. Further assessment of microstructural
examination was conducted with the morphology and the location of the
pits. The experimental results showed that the corrosion rate was the
highest in the sample with the least of silicon content, which is ADC
12. Microstructural observation with areal analysis revealed that the
pitting morphology at the eutectic silicon and intermetallic phases
being dependent upon the interface with the aluminum phase. More
interface area promotes more pittings, since the pitting corrosion are
more active at the interfaces.
Keywords: Die-cast, Corrosion, Aluminum, Silicon.
Abstract - In this study, an experimental pilot scale two-phase, direct contact heat exchanger was constructed and tested. Experiments were performed using water as the dispersed phase and boiler exhaust hot gases as the continuous phase. This kind of direct contact heat exchanger is called supermizer. Test results indicate that supermizer has high thermal effectiveness and is very effective in reduction of the environmental pollutants in boiler exhaust hot gases. It can reduce unburnt hydrocarbons and carbon monoxide entering atmosphere more than 50% and 30% respectively and its thermal effectiveness is 95.2%. In order to improve the performance of the supermizer, this paper presents a new system called combined system. A comparison between atmospheric pollutant reduction in supermizer and combined system shows that the combined system is more efficient than supermizer in pollutant reduction. In the combined system, the amount of carbon monoxide and unburnt hydrocarbons can be reduced about 25% and 10% more than supermizer, respectively. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Supermizer, Combined system, Dispersed phase, Continuous phase.
Abstract -
The sun is a clean and renewable energy source, which produces neither
green house effect gases nor hazardous wastes through its utilization.
Algeria is considered as one of the world regions that receive a great
portion of solar radiation per year. In some remote areas, where this is
the case, a judicious combination of other renewable Sources to form a
Photovoltaic or hybrid system can help solve rural electrification
problems, where the grid extension is costly and the cost of fuel
increases drastically with the remoteness of the location. On the other
hand the surface of south Algerian is over 2.000.000 Km2,
where just the town of Adrar is 400.000km2, which make
operation of extension the electric grid in remote area very hard and
very expensive, like small villages called (ksours) situated in center
of desert. Small off-grid standalone renewable energy systems represent
an important option for narrowing the electricity gap in rural parts of
the developing these remote ksours in Adrar. The aim of this study is to
analyze long-term solar radiation data of Adrar (south of Algeria) to
assess the techno-economic feasibility of utilizing PV–battery power
systems to meet the load of a typical house building with annual
electrical energy demand of 4000 kWh. The power load of house is
calculated on the basis of Algerian finance law of year 2008, for an
average family. The government through this law, pays 50% of electricity
consumes with a maximum threshold of 4000KWh per annum. Hybrid
Optimization Model for Electric Renewable (HOMER) software has been
employed to carry out the present study. Optimization modeling
demonstrates that 100% of power demand can be supplied by a PV
configuration composed of 2kW PV system together with a battery storage
of 37, 5 h of autonomy. The PV penetration is 142%, the cost of
generating energy (COE, US$/kWh) from the above Pv system has been found
to be 0.42 $/kWh. Attention is focused on gain of reduction in carbon
emissions, cost of PV only – PV battery systems, etc, A secondary aim is
to analyze the role of the Algerian decree for developing the renewable
energy in Algeria general and in south specifi for application this
study.
Keywords: Photovoltaic, Solar Radiation, Law, Homer.
Abstract - The objective of this work is to estimate tendon forces and fingertip strength during the generation of functional static forces for the normal, the pathological and the surgical reconstructed fingers. A 3D biomechanical model for the static force analysis was developed. This model takes into account all the tendons in the fingers and their related moment arms. Optimization approaches are used to solve muscular redundancy, to obtain a tendon forces distribution and to quantify optimal pinch strength. The model is compared to other previous published works. For the repaired hands, the outcomes of two common tendon transfers are explored. The Br-FPL transfer used to restore the thumb IP joint flexion. The FCU-EDC transfer used to reanimate the index finger extension. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Tendon Force, Index Finger, Thumb, Biomechanical Model, Optimization, Tendon Transfer.
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