Latest issue

by A. Amoresano, V. Avagliano, V. Niola, G. Quaremba

Vol. 7. n. 6, pp. 999-1006

Abstract - The aim of this paper is to illustrate a methodology for identifying and analysing the performance of an I.C. engine and, at the same time, for the reconstruction of the morpho-dynamical vibration. Some technical considerations and a real application explain the method by completing the description of the phenomena observed. It allows to focus a methodology which should concur to the improvement of the diagnostics of anomalies useful for determining the correct operating process of an I.C. engine.

Keywords: IC Assessment, Wavelet Transform, Morpho-Dynamical Vibration .

by A. Amoresano, G. Langella, V. Niola, G. Quaremba

Vol. 7. n. 6, pp. 1007-1013

Abstract - In this paper a spray behaviour based on digitalised images is presented for a specific fluid the working range of a spray, the main parameters indicating the spray performances, e.g DeLavan data sheet, cone angle, supply pressure and mass flow rate are defined. Such parameters determine the spray behaviour but they don’t give any answer about the main parameter whose variation determines a different pattern of the atomization. To atomize a high viscous fluid and to achieve an efficient lubrication, the drops of the spray jet have to coalesce and form a continuous liquid film in a very short time. To achieve this kind of behaviour the spray has to generate the droplets in a particular range of diameters so, their deformation after the impact, have to minimize the coalescence time. In this paper the behaviour of a pressure swirl spray working with a high viscous fluid its spectra of droplets and a numerical simulation of the internal flow are presented.

Keywords: Lubrication, Viscous Liquid, Spray Characterization.

by A. Amoresano, V. Avagliano, V. Niola, G. Quaremba

Vol. 7. n. 6, pp. 1014-1020

Abstract - In the aircraft industry a strong demand for weight reduction is mainly oriented to the requirements of a more stringent containment of pollution and lower fuel consumption. The potential offered by innovative joining technologies such as welding Friction Stir Welding (FSW) and other, known for some time, allow to hypothesize a significant reduction of weight. Starting from these considerations, the aim of this work is the determination, through a technical and non-destructive method, of the residual internal stresses of aluminium T-joint skins welded by means of the FSW technology. In particular the goal of this paper is to illustrate the selective capacity of the proposed methodology for the identification of longitudinal and transverse stresses. In the first part of the work a brief introduction to the problem is presented; in the second part were described the specifications of the FSW process and the materials welded in T-join configuration used. In the third part was described the non-destructive method proposed for determining internal stress state of aluminium T-joint skins. In the last part of this paper were reported the results obtained by applying the method to the welded T-joints with the FSW technology.

Keywords: Internal Stress Analysis, Non-Destructive Control, Wavelet Transform, Two-Dimensional Fourier Transform.

by Mohammed Sammouda, Kamal Gueraoui, Mohamed Driouich, Abdelhak Ghouli, Abdelhak Dhiri

Vol. 7. n. 6, pp. 1021-1030

Abstract - We studied in this paper the phenomena of double-diffusive convection in a cylindrical enclosure filled with a porous medium saturated with a Newtonian fluid. The porosity of the porous media is variable from the walls to the bulk and follows an exponential law. The enclosure is heated from below and two mass concentrations C0, C1 are applied respectively to the surfaces (bottom, top) of the cylinder. The vertical walls are rigid, impermeable and adiabatic. An extended law of Brinkman-Forchheimer (EBFD) describes the fluid flow occurring in the porous layers by using the Boussinesq approximation. The mass concentration follows the basic Fick law, and the model chosen to describe the heat transfer is based on the approximation of one temperature. The heat and mass flow are controlled by the dimensionless numbers such as Rayleigh, Lewis, Darcy, Prandtl number that appear by dimensionless of the system of equations. The finites differences method is used to solve numerically the problem. The study focused on the effect of the dimensionless numbers on the concentrations and on the rate of heat transfers profiles in the overall Nusselt number, while considering the porosity uniform or non-uniform. The numerical code developed can be used for various industrial processes involving the phenomenon of natural convection.

Keywords: Natural Convection, Porous Media, Variable Porosity, Cylindrical Cavity, Extended Darcy Law.

by Ali M. Jawarneh

Vol. 7. n. 6, pp. 1031-1036

Abstract - Flow characteristics in a sink-swirl flow within two disks are examined experimentally and numerically. The experiments and the predictions have been carried out for three bulk Reynolds numbers and four contraction ratios. Results show that as the contraction ratio and the Reynolds number increase, the pressure coefficient increases. Stronger vortices will be produced resulting in a higher tangential velocity and hence a higher pressure drop. The radial pressure decreases slowly from the inlet periphery up to halfway along the disk and then decreases sharply as the flow approach the exit hole. Air enters through the peripheral gap between the two disks and converges to the center where it discharges axially through the exit hole. This indicates that the flow moved towards a more favorable pressure gradient, hence the vortex flow accelerated according to the angular momentum conservation. It can be seen that the Reynolds stress model gives good agreement with the present experimental data and the percentage difference error between the predicted and experiments is less than 10%.

Keywords: Contraction Ratio, Two Disks, Sink-Swirl Flow, CFD, Vortex Generator.

by Md. Moslemuddin Fakir, Sabira Khatun, S. B. Basri

Vol. 7. n. 6, pp. 1037-1043

Abstract - Finite Element Method (FEM) and Differential Quadrature Method (DQM) are two very important numerical solution techniques to solve engineering and physical science problems. Usually elements are sub-divided uniformly in FEM (Conventional FEM, CFEM) to obtain temperature distribution behavior in a fin or plate. Hence, extra computational complexity is needed to obtain a fair solution with required accuracy. In this paper, non-uniform sub-elements are considered to enhance the CFEM algorithm to reduce the computational complexity. The proposed algorithm is known as Efficient FEM (EFEM).This EFEM is applied for the solution of one-dimensional heat transfer problem in convection-tip thin rectangular fin. Exact solutions are also obtained for comparison purpose. The obtained results are compared with CFEM and Efficient DQM (EDQM), with non-uniform mesh generation. It is found that the EFEM exhibits more accurate results than CFEM, EDQM and agrees with exact solution showing its potentiality.

Keywords: Efficient Finite Element Method, Heat Transfer, Efficient Differential Quadrature Method.

by L. Rahmani, B. Draoui, , E. Benachour, B. Mebarki, Oussama Seghier

Vol. 7. n. 6, pp. 1044-1052

Abstract - In this work the characterization of hydrodynamic fields of incompressible yield stress fluid with regularization model of Bercovier and Engelman in a cylindrical vessel not chicaned equipped with circular anchor stirrer was undertaken by means of numerical simulation using computational fluid dynamics. Simulations flow of a Bingham fluid agitated by straights blades anchor was used to validate the rheological model implemented of the fluid treated. The flow structures, and especially the effect of inertia, the plasticity and the yield stress, are discussed. We have analyzed also the influence of rheological parameters on the hydrodynamic flow behaviours, such as the velocity components and the global characteristic like power consumption.

Keywords: Mixing, Stirred Vessel, Anchor Impeller, Yield Stress, Computational Fluid Dynamics (CFD).

by R. Brinda, R. Joseph Daniel, K. Sumangala

Vol. 7. n. 6, pp. 1053-1061

Abstract - Micro-fluidic heat sinks are generally regarded as an effective method for the heat transfer in integrated electronic circuits and much effort has been put into improving their capacities A collection of parallel ladder type micro channels with rectangular cross section have been introduced and extensively studied by the authors for heat sinking in ULSI circuits and their performance has been reported to be superior to conventionally used collection of parallel rectangular micro channels. This paper focuses on the ladder type micro channel heat sinks with three different cross-sectional shapes with constant area (rectangular, trapezoidal, and triangular) in order to bring out the influence of cross sectional shapes on the heat sinking performance and attempts to identify the cross sectional shape that can ensure lower thermal resistance and highest value of convective heat transfer coefficient h. The flow performance of these three shapes of ladder type micro channels have been studied using COMSOL multiphysics and the comparison of the flow performance indicating parameters of the three shapes show that better hydraulic performance can be achieved using the ladder type triangle micro channels. Further the thermal responses of these micro fluidic systems have also been studied extensively using coupled thermal - hydraulic analysis and these studies show that the lowest thermal resistance and highest value of convective heat transfer coefficient h is achieved with the introduction of ladder type triangle micro channels followed by trapezium and rectangle shape micro channels.

Keywords: Hydraulic Performance, Ladder Type Micro Channels, Micro Channel Heat Sinks, Rectangular, Thermal Performance.

by H. Volkan Ersoy

Vol. 7. n. 6, pp. 1062-1068

Abstract - While the disks having the same angular velocity are initially rotating about a common axis, the unsteady flow produced by their oscillations in their own planes and in the opposite directions is investigated. It is shown that the solutions for all times are obtained by means of the analytical solutions corresponding to small and large times. The dependence of the velocity field on the time, the kinematic viscosity of the fluid, the angular velocity and gap of the disk, the frequency and velocity amplitude of the oscillation is examined in terms of the appropriate dimensionless parameters. It is observed how the periodic motion of the fluid takes place when the time is large enough.

Keywords: Concentric Rotating Disks, Newtonian Fluid, Non-Torsional Oscillation, Unsteady Flow .

by Ahmed M. Adham

Vol. 7. n. 6, pp. 1069-1073

Abstract - In this paper, the optimization of a nanofluid-cooled microchannel heat sink was reported. Al₂O₃-NH₃ with three different volume fractions (1 %, 3 % and 5 %) was examined. An optimization scheme which is comprised of two objective functions (thermal resistance and pumping power) and the elitist non-dominated sorting genetic algorithm (NSGA-II) was employed to optimize the overall performance of the considered system. Under the same operating conditions, the ammonia-base nanofluid (Al₂O₃-NH₃) exceeded other coolants (Al₂O₃-H₂O and H₂O) in terms of the required pumping power (0.144, 1.015 and 0.94 W for Al₂O₃-NH₃, Al₂O₃-H₂O and H₂O, respectively). When the refrigerant base nanofluid is used as a cooling fluid, a lighter heat sink was produced. Finally, more studies should be dedicated to explore this nanofluid and the possibility of considering it for electronic systems cooling.

Keywords: Nanofluid, Refrigerant, Microchannel, Heat Sink, Optimization.

by L. Rahmani, , B. Draoui, , M. Bouanini, E. Benachour

Vol. 7. n. 6, pp. 1074- 1079

Abstract - In this work, we study the case of highly viscous fluids in a classical system of agitation: a cylindrical tank with plate bottom without obstacles agitated by a gate impeller agitator. We devote to a numerical approach carried out using an industrial code CFD Fluent 6.2.13 based on the finite volumes method discretization of Navier - Stokes equations formulated in variables (U.V.P). The threshold of flow related to the viscoplastic behaviour is modelled by a theoretical law of Bingham. Heat transfer to Bingham plastic fluids in an agitated vessel .It is a commonly used in chemical and food industry processes. However, little is known about the effects of mixing system geometry and the influence of rheological properties of the liquids on the heat transfer phenomenon. The hydrodynamic and thermal behaviours induced by gate agitator. Heat transfer is applied on the jacketed wall of the stirred vessel. Solutions of the time-averaged Navier–Stokes and energy equations are developed using a control volume discretization method. Streamlines and isotherm represent the corresponding flow, field and the global distributions of Nusselt number are also presented.

Keywords: Agitated Vessel, 2D Modeling, Bingham Fluid, Heat Transfer, Gate Impeller, CFD.

by Hassene Djemel, Mounir Baccar, Mohamed Mseddi

Vol. 7. n. 6, pp. 1080-1086

Abstract - This research work presents a three-dimensional numerical study of the thermal and hydrodynamic behavior in the turbulent flow of the cross-flow heat exchanger named intercooler. Two 3-D intercooler models are performed in the calculations. Indeed, while the first one is formed by continuous fins, the second is formed by offset strip fins. The geometric configuration as well as the mesh of the computational domain are developed using commercial "Gambit 2.4.6" software. On the other hand, the ANSYS-Fluent 6.3.26 code is used to compute the velocity and temperature fields. Compared to the continuous fin configuration, the numerical simulation shows that the increase in the heat transfer in the offset strip fin configuration is higher. This proves that the excellent performance of this offset strip fin and the efficiency of intercooler have been augmented with about 20 %. The performances of the heat exchanger using numerical simulation are compared with those produced by the NTU method (Number of Transfer Units) and found to be in good agreement.

Keywords: Heat Exchanger, Intercooler, Numerical Model, k−ε Model, Turbulent Flow.

by Khaleel AL Khasawneh, Mohammad Tarawneh

Vol. 7. n. 6, pp. 1087-1093

Abstract - This study analyzed a highly rarefied gas flow fields inside an enclosure. The enclosure is formed by four plates with two different temperatures. The plate surfaces are assumed completely diffuse; at the final steady flow stage for any point inside the enclosure or at the surface, the velocity distribution function was determined and all the macroscopic properties was determined by integrating the velocity distribution function. First, the collisionless flow solution was considered as the base solution, and then based on the Bhatnagar-Gross-Krook model, the characteristic relaxation time scale τ was used as a small parameter, and obtained general asymptotic analytical solutions for the flow fields and heat transfer expressions. To validate these asymptotic solutions, a series of numerical simulations with the direct simulation Monte Carlo method were performed and compared with the analytical results. In general, as Knudsen number decreases, the solutions for the pressure, temperature, and density fields deteriorate; the temperature fields had relatively better agreement than the density and pressure fields.

Keywords: Heat Transfer, Rarefied Flows, Micro-Electro-Mechanical System Devices, Monte Carlo Simulation Method.

by N. Thangavelu, N. Mohandoss Gandhi

Vol. 7. n. 6, pp. 1094-1102

Abstract - The condensation of steam on single horizontal copper tube in a shell and tube condenser has been investigated using experimental and theoretical methods in this study. The outer surface of the tube was modified by brazing it with a copper wire longitudinally and helically to enhance the heat transfer coefficient. The effect of varying the pitch of the helically brazed wire was studied with 25mm and 35mm pitch. Longitudinally Wire Brazed(LOWIB) and Helically Wire Brazed (HEWIB) copper tubes with pitch 25mm and 35mm were found to increase the heat transfer coefficient by a factor of about 1.5, 2 and 1.2 respectively. CFD is found to be an alternate method to time and cost consuming “PROTO BASED EXPERIMENTAL” techniques. In this work the CFD results obtained using ANSYS 13 are validated with experimental results to achieve the best practice of CFD in this case. This best practice is utilized to find out the best modification in which rate of heat transfer is maximum and the deposition of condensate on the cold water pipe is minimum.

Keywords: Computational fluid dynamics, Condensation, Enhancement of heat transfer coefficient, Modelling and numerical simulation, Wire wrapped tube.

by Makhloufi Z., Bederina M., Bouziani Tayeb, Kadri E.H., Bouhicha M.

Vol. 7. n. 6, pp. 1103-1114

Abstract - In this study, we present the formulations of superplasticized concrete based on limestone aggregates of Turonian. Three granular fractions of limestone aggregates have been used and undergone a series of normative tests in order to achieve characterization, more or less detailed, which allows appreciating the quality of these aggregates according to the standards in vigour. Crushed limestone sand (0/5 mm) and crushed gravels (5/15 and 15/25 mm) are used for the preformulation of concrete. The method of Dreux-Gorisse, which uses a graphic process, has been followed in order to determine, in an approximate way, the weight proportions of the various components of concrete. Then, the Baron-Lesage method has been used to experimentally determine the optimal mixture giving the best compactness. The properties of fresh and hardened concrete were assessed by the study of the Abrams cone slump and the strengths of compressive and splitting tensile which were measured on standardized specimens (cylinder: 16 x 32 cm). The various tests carried out in laboratory led to a series of experimental results that have enabled to establish equations adjustment, curves and an abacus that seem easy to use.

Keywords: Formulation, Concrete, Limestone Aggregates, Superplasticizer, Slump Test, Adjustment Law, Tensile Strength by Splitting, Compressive Strength, Abacus.

by M. Borodachenkova, S. Santos, F. Barlat, J. J. Gracio

Vol. 7. n. 6, pp. 1115-1120

Abstract - In the present work, a new model (MARISAL) that describes the mechanical behavior of Al-30wt%Zn alloy under compression is proposed. MARISAL is a microstructure-based model, which takes into account the effects of solid solution decomposition, Orowan looping and grain refinement on the mechanical behavior. As an overall result of these mechanisms, the material is subjected to initial softening under deformation that saturates at moderate plastic strains. The MARISAL model describes softening and saturation based on a simple evolution law relating the dislocations mean free path to plastic strain.

Keywords: Al-Zn Alloys, Compression, Grain Refinement, Modelling, Precipitates, Solid Solution.

by Z. A. Rasid, R. Zahari, A. Ayob

Vol. 7. n. 6, pp. 1121-1127

Abstract - Thin composite structures that are used in aerospace applications can be subjected to buckling failure due to combined mechanical and thermal loadings. This paper presents the work on the thermal post-buckling improvement of composite plates previously subjected to mechanical loading. Pre-strained shape memory alloy wires were embedded within laminated composite plate so that the recovery stress that can improve strain energy of the plate can be induced when the wires were heated. A geometric non-linear finite element formulation of the shape memory alloy composite plate and its source codes were developed. The formulation is based on total strain for the case of mechanical loading and incremental strain for the case of thermal loading. Using the codes, post-buckling paths were determined for quasi-isotropic and anti-symmetric cross-ply composite plates. It was found that by embedding shape memory alloy wires within composite plates, thermal post-buckling paths can be improved significantly even after the degradation of the thermal buckling resistance of composite plates due to the application of the mechanical loading.

Keywords: Shape Memory Alloy, Strain Energy Tuning, Non-Linear Finite Element Formulation, Thermo-Mechanical Post-Buckling.

by V. Saravanan, P. R. Thyla, S. R. Balakrishnan

Vol. 7. n. 6, pp. 1128-1132

Abstract - The current study investigates the possibility of substituting an alternate material for Aluminium Alloy (AA 6063) which is being used in multi cylinder Engines. In this work damping effect and dynamic performance comparison were the main focus. The substitute material taken for comparison was 10 percentage volume Cenosphere reinforced Aluminium Alloy (AA) 6063 Metal Matrix Composite (MMC). Impulse dynamic test, Modal and Harmonic analysis were performed on specimens based on ASTM standard. The result of the composite specimen was compared with that of AA6063 material which is used for cylinder. Based on the experimental result, dynamic behavior of the engine block was predicted using finite element analysis.

Keywords: Aluminium, MMC, Engine Block, Cenosphere, Finite Element Analysis.

by D. Philip Selvaraj, P. Chandramohan, M. Mohanraj, P. K. Rajesh

Vol. 7. n. 6, pp. 1133-1141

Abstract - In this work, the cutting parameters in end milling operations of nitrogen alloyed duplex stainless steel are optimized by using Taguchi method. The end milling tests are conducted at three different spindle speeds and feed rates with constant depth of cut. The signal to noise ratio and analysis of variance are used to investigate the cutting characteristics. The wear rates in the tool inserts are examined by scanning electron microscope. The analysis of the results shows that the feed rate and spindle speed are the most significant parameters influencing the cutting force and surface roughness. It is also found that, the spindle speed is the most significant parameter and feed rate is less significant parameter influencing the tool wear. The confirmation tests are carried at optimum cutting conditions to validate the predicted results. High flank and rake wear are observed at higher spindle speed and feed rate.

Keywords: Cutting Force, Duplex Stainless Steel, End Milling, Optimization, Surface Roughness, Taguchi Method, Tool Wear.

by A. Anandha Moorthy, N. Natarajan, P. K. Palani, M. Manojkumar

Vol. 7. n. 6, pp. 1142-1146

Abstract - AA2218 based self-lubricating metal matrix composite was prepared with 5, 10 & 15 weight percent of fly ash and 4 weight percentage of MoS₂. Dry sliding wear behavior of self lubricating composite was tested at room temperature by pin on disc wear testing apparatus. Wear rate, Coefficient of friction and volume loss of self lubricating composite has been tested as the result of applied load, sliding velocity and weight percent of fly ash particles. From this investigation it was observed that the wear rate increases with the increasing load, at the same time wear rate and coefficient of friction get reduced to increase in wt. % of fly ash particles. Another dominant factor is the formation of the tribochemical layer at the interface, which was formed by MoS₂. Formation of tribochemical layer was clearly observed from SEM micrographs. This study reveals that wear resistance of the self-lubricating composites containing 15 wt. % fly ash and 4 wt. % MoS₂ has been superior to that of the other compositions.

Keywords: AA2218, Fly Ash, MoS2, Ashalloy, Stir Casting Process, Pin-On-Disc.

by Sivaraos, A. A. Aziz, R. Izamshah, Taufik, A. Hambali

Vol. 7. n. 6, pp. 1147-1151

Abstract - This paper presents an innovative Super Energy Saving Locking System (SES-Lock) which was derived to overcome the limitations faced by the popularly being used electro-magnetic (EM- Lock) door locks. EM-Lock continuously consumes electricity (almost 24 hours) let it to be when the door is in the locked or unlocked conditions, besides requiring a backup battery in case of power failure to avoid the lock from malfunction. It is also pretty much easier to be electrically or mechanically hacked with a little bit of skill in breaking in. Therefore, Super Energy Saving Locking System (SES-Lock) was critically engineered, in such a way that it does not at all consume power supply when the door is in the locked or unlocked conditions, which enabled the power saving almost up to 95% compared to EM lock of the same capacity. The system was also intelligently innovated in which no back-up battery is required for SES-Lock during a power failure, where the system can still remain locked as usual and can be easily opened using embedded fail safe and fail secure administrative key operated mechanically. SES-Lock is fully compatible and can be integrated with the common door access control system regardless of its type namely key pad, card swipe, or biometric. Its body structure was designed with Al alloy 6061-T6 material to withstand if not same for better mechanical and electrical performance compared to EM-Lock.

Keywords: Energy Saving Lock, Ses- Lock, Electromechanical Lock, Stress Analysis, Finite Element Analysis.

by I. Zahari, M. A. Abas, N. I. Mat Arishad, S. F. Zainal Abidin, M. F. Muhamad Said

Vol. 7. n. 6, pp. 1152-1158

Abstract - This paper describes an experimental study conducted to identify the common engine part load conditions between Malaysian city driving and NEDC (New European Driving Cycle) test on a 4 cylinder gasoline fuelled engine, with multi-point fuel injection system, and continuous variable transmission vehicle. This is to pinpoint a regional area from the part load map in the attempt to strategize key technologies such as CDA (Cylinder Deactivation) or CNG (Compressed Natural Gas). Technologies such as CDA or CNG do not operate at all engine operations. Due to certain drawbacks, the operation of the technologies must be strategized to obtain most benefit from the engine. With the knowledge of the common part load region, these technologies could be integrated and strategized into the region to reduce overall fuel consumption. With improvements in fuel consumption respective to the identified common part load operations, the overall fuel consumption benefit does not only serve the legislation but also most importantly benefit the local consumers who travel on Malaysian roads.

Keywords: Part Load, Fuel Consumption, City Driving, NEDC.

by Shashikant S. Patil, A. B. Auti, T. P. Singh

Vol. 7. n. 6, pp. 1159-1163

Abstract - In domestic desalination system, salt water is heated and converted to steam by using conventional system like LPG or using induction cooker. The steam is then condensed by the condenser without using electricity which is designed on the basis of the thermal analysis. Condenser consists of a water tank with copper tubes immersed in it.CFD analysis is done for the different diameter and length of pipes and the more effective pipe is found out. Similarly, different shapes of the selected pipes in the tank are decided using CFD analysis. Finally the system is validated using experimental analysis.

Keywords: Condenser, LMTD, Nodes, Skewness.

by A. M. Kassim, T. Yasuno, Sivaraos, H. I. Jaafar, F. A. Jafar

Vol. 7. n. 6, pp. 1164-1170

Abstract - In this paper, the generation of brake motion control for our developed quadruped hopping robot while moving on two dimensional spaces by jumping continuously is discussed. The braking motion method which is approached is by applying the reference height control system to create the differences of front leg and back leg while making moving performance and correct the body posture which has inclined to make the quadruped hopping robot jump vertically while braking performances. On the other hand, this approached method can be used as the collision-avoidance behavior for the quadruped hopping robot. The MATLAB/Simulink model is used in order to conduct the pattern generation of quadruped hopping robot. As the result, effectiveness of approach method is confirmed to generate brake motion control of quadruped hopping robot while making continuous jumping vertically.

Keywords: Quadruped Hopping Robot, CPG Networks, Moving and Braking Motion Control.

by S. Devi, L. Sivakumar, M. Saravanan

Vol. 7. n. 6, pp. 1171-1179

Abstract - The article presents modeling of a 40 MW power plant using the observed onsite data using ANN and MLR models. The four different structures of neural networks are employed in two stages which are then integrated into a single ANN model representing a complete model of the thermal power plant. The method is further compared with the multiple linear regression (MLR) method and their detailed statistical error analysis showed that the ANN models present a very good accuracy with correlation coefficient of 0.999209 which makes these models fast in response and easy to be updated with new plant data. These measures clearly demonstrated the efficient prediction accuracy of the neural networks in modeling of the 40 MW power plants.

Keywords: Thermal Power Plant, Coal-Fired Boiler, Steam Turbine, Artificial Neural Network, Multiple Linear Regression.

by S. Sellakumar, R.Venkatasamy

Vol. 7. n. 6, pp. 1180-1188

Abstract - This paper presents a review of technical reports available for the structural assessment of pipe bends. Compared with smooth bends, the volume of literature available for joint bents (mitres) is less and least explored in challenging applications, such as low temperature use. The issue that affects a pipe bend is discontinuity stresses and cross-section ovalisation. These lead to delay in the enlargement of non-linear analysis of pipe bends. The constrains of pipe work designers are thoroughly analyzed and discussed, together with the effects of loading and out-of-circularity. The scope for additional work on the effect of combined loading, and end effects, out of- circularity are high. Limit, collapse and disintegrate loads are not yet obtainable across the entire continuum of bends and loading parameters. Creep and optimization is least explored as far as pipe bends are concerned. The presence of unforeseen vibration is a common source of high-cycle weakness collapse in pipe work, resulting vibration-induced fatigue studies.

Keywords: Ovality, Pipe Bend, Structural Analysis.

by Shahin Nayyeri Amiri, Asad Esmaeily, Javad Safadoust

Vol. 7. n. 6, pp. 1189-1193

Abstract - Free, large radial oscillations of multi-layered, thin, long, pipes are investigated using the theory of finite elastic deformations. The material of each layer is assumed to be homogeneous, isotropic, hyperelastic and incompressible. Closed form solutions are obtained for the nonlinear, ordinary differential equation governing the motion of the inner surface of the cylinder pipe. The motions of the other material points can then be obtained using the incompressibility condition. It is shown that the radial stress is negligible throughout the thickness of the pipe. Tangential stress distributions at different times are given as a function of the radial distance for one, two and three layer pipes.

Keywords: Stress, Thin-Walled, Multi-Layer Pipes, Large, Radial Vibration.

by A. Kherraf, K. Zidani, H. Mazouz, L. Chelghoum, L. Rezoug

Vol. 7. n. 6, pp. 1194-1197

Abstract - This study is devoted to numerical modeling and simulation of the process of forming of metal powders by hot isostatic compaction (HIC) for the production of parts in biomechanics. A continuous model based on a visco plastic law is used to describe the process of densification HIP (hot isostatic pressing). The model was implemented in a finite element code developed under the platform FORTRAN POWER STATION. For numerical simulation, we considered a cylindrical die subjected to isostatic pressure and a temperature field. We study variations of different parameters: relative density and radial shrinkage. To validate the numerical model, the results are compared with experimental data.

Keywords: Hot Isostatic Compaction, Relative Density, Radial Shrinkage, Powder Mettalurgy, Finite Element Method, Visco Plastic Model.

by S. Rajesh, K. Marimuthu

Vol. 7. n. 6, pp. 1198-1206

Abstract - This paper describes the development of on-line wear state monitoring system in drilling process on Vertical Machining Centre (VMC). In this work, standard data acquisition software LabVIEW (Laboratory Virtual Instrumentation Engineering Workbench) in the application of Virtual Instrumentation (VI) has been applied to predict the drill wear states of High Speed Steel (HSS) drill bit for drilling on a AISI 1018 Steel work piece. Drill wear state prediction allows the determination of the hole quality as well as tool replacement at proper time, during machining. Drilling experiments have been carried out over a wide range of varying cutting conditions (cutting speed, drill diameter, feed-rate) and the effects of drill wear on the spindle motor cutting current signals have been investigated. The effective drill wear model has been established to predict the drill wear states based on the relationship between the spindle motor cutting current signals and the various cutting parameters, using LabVIEW. The established on-line drill wear process monitoring system has been used for the continuous monitoring of the cutting tool status, and to exhibit the drill wear states as a percentage of the maximum permissible wear. Meanwhile, it facilitates defective tool replacement at the proper time in an automated manufacturing environment, and found to be in very good agreement to the experimentally determined drill wear values.

Keywords: Cutting Current Signals, Drill Wear Monitoring, AISI 1018 Steel, LabVIEW, VMC.

by P. Karunakaran, C. Jegadheesan, C. Rangasami, P. Sengottuvel

Vol. 7. n. 6, pp. 1207-1212

Abstract - The present work investigates the use of silica sand, fly ash and bentonite mixture in the preparation of castings. Samples of silica sand and steel industry fly ash were collected and their basic properties studied using X-ray diffraction, thermogravimetric analysis, scanning electron microscopy and energy-dispersive spectroscopy. Cylindrical AFS samples were prepared with 4%, 8%, 12%, 16%, 20%, 24%, 28%, 32%, 36%, 40%, 44%, 48% and 52% of fly ash, and 1%, 2% and 3% of bentonite by weight basis. Permeability, green compression strength and dry compression strength of these samples were analyzed using permeability meter and universal strength machine (USM). The compression strength of silica sand–fly ash mixture was low initially but increased after addition of bentonite, the reason being that bentonite addition provided a layer of coating around silica sand grains, thereby filling the voids and reducing the hydraulic conductivity of silica sand mixture. It has been found that 24% steel industry fly ash and 3% bentonite in silica sand is optimum for preparing castings.

Keywords: Bentonite, Casting, Compression Strength, Fly Ash, Optimization of Concentration, Permeability, Silica Sand.

by Maruthai Suresh, Chinnappan Selvakumar, Ranganathan Rani Hemamalini

Vol. 7. n. 6, pp. 1213-1217

Abstract - The main contribution of this paper is to design active disturbance rejection control for a nonlinear thermal process to track reference signals while operating under the influence of disturbances. A linear active disturbance rejection controller is designed through an extended state observer to estimate and compensate the uncertainties of the system. The simulation result demonstrates very good performance of the controller in the absence of an accurate mathematical model of the process.

Keywords: Nonlinear Process, ADRC, ESO, Controller.

by Nor Azwadi C. Sidik, Syahrullail Samion

Vol. 7. n. 6, pp. 1218-1222

Abstract - In this paper, the lattice Boltzmann method, a mesoscale numerical tool based on particle distribution function is used to simulate thermal fluid flow in porous media. The key point is to combine the simplest four and nine lattice velocity model to represent the temperature and density distribution functions respectively. A wide range of Rayleigh numbers and material's porosity was applied to study their effects on the thermal fluid flow in the enclosure. The numerical experiments demonstrated excellent agreements when the computed results were compared with those predicted by the finite element solution to the Brinkmann-Forccheimer equation and the conventional lattice Boltzmann scheme. This indicates the applicability of the present approach in the realistic simulation of thermal fluid flow in porous media.

Keywords: Lattice Boltzmann, Double Population, Natural Convection, Porous Media.

by Ehsan Kianpour, Nor Azwadi C. Sidik, SyahrullailSamion

Vol. 7. n. 6, pp. 1223-1228

Abstract - This study was carried out to find out the effects of cylindrical and row trenched cooling holes with alignment angle of 90 degree on the film cooling performance adjacent the end wall surface of a combustion simulator. In this research a linear representation of a true Pratt and Whitney gas turbine aero-engine was simulated and analyzed. The current study has been performed with Reynolds-averaged Navier-Stokes turbulence model (RANS) on internal cooling passage. This combustor simulator combined the interaction of two rows of dilution jets, which were staggered in the stream wise direction and aligned in the span wise direction. The entire findings of the study declared that when, the row trenched holes used the, near the enwall surface, film cooling effectiveness is almost two times more than film cooling performance of baseline case.

Keywords: Gas Turbine, Film Cooling, Thermal Contour, Cylindrical Holes, Trenched Holes.

by M. E. Zailani

Vol. 7. n. 6, pp. 1229-1235

Abstract - This paper focuses on the feasibility study ofDish Stirling systems in Malaysia from technical simulations using System Advisor Model (SAM), a software developed by the National Renewable energy Laboratory as a step towardsmore environmentally cleaner solutions to electrical power generation. Kuala Lumpur, Malaysia’s capital city, experiences an annual Global Horizontal Irradiance of 1561.9 kWh/m² and low Direct Normal Irradiance of 373.1 kWh/m² due to high reflection and scatter by present clouds. The highest annual energy output of DS systems in Malaysia is located in Georgetown at 739,524 kWh, however, representing only 14 % of annual energy output in Phoenix. Simulations results conclude Malaysia as a location unsuitable for Dish Stirling systems and potentially other Concentrated Solar Power systems.

Keywords: Direct Normal Irradiance, Dish Stirling Systems, Global Horizontal Irradiance, Malaysia.