Feb'2020

Welcome to The IUP Journal of Mechanical Engineering

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The authors have considered a Double Pipe Heat Exchanger (DPHE) and various insert configurations of turbulators-Inner Side Triangular Ribs (ISTR) on both outer and inner pipe of DPHE, a helical spring on outer side of inner pipe of DPHE, and combined ISTR (inner) and helical spring wrapped over inner pipe. The study suggests that the turbulators inserted inside heat exchanger increase the Nusselt number by about 1.7 times for the triangular rib arrangements and about 1.3 times for spring arrangement over the tube without turbulator. The friction factor is found to be higher in case of ISTR on inner and outer pipe as compared to other arrangement due to higher blockage area which deflects the flow. At similar operating conditions, due to the improved turbulence and enhanced swirl flows, various arrangements of triangular ribs and helical springs as inserts in DPHE perform better in heat enhancement.

Small wind turbines of the 8-100 kW range serve as good sources of small-scale economically independent energy for agricultural and industrial consumers. Recent evidences point out that many small turbines are underperforming in the field compared to theoretical projections due to manufacturing defects and the aerodynamic design of the airfoil. In the paper, "Understanding the Performance Degradation of Small Stall-Regulated Wind Turbines Due to Typical Manufacturing Defects", the authors, Amool Raina, Kyle Wetzel and Saeed Farokhi, have presented the results of aerodynamic investigation of the wind turbine airfoils using Computational Fluid Dynamics (CFD). The authors have focused on the simulated effect of typical manufacturing on the performance of airfoils and on the effects due to critical Reynolds number range on these airfoils. The simulation results suggest that manufacturing flaws at the leading edge and camber distribution might have led to severe performance degradation, and also that the transitional Reynolds number range of 100k-300k may create multiple laminar separation bubbles that limit the aerodynamic performance of the airfoil sections.

Welding is a process of joining two similar or dissimilar metals by fusion, with or without the application of pressure, and a filler metal may be used if required. Gas Tungsten Arc Welding (GTAW) or Tungsten Inert Gas (TIG) welding is an arc welding process that employs a tungsten (nonconsumable) electrode to produce the weld. Shielding gas (usually an inert gas) is used to protect the weld zone from atmospheric gases. Thin sections of stainless steel and nonferrous metals such as aluminum, magnesium and copper alloys are generally welded by TIG welding. In the paper, "Optimization of TIG Welding Process Parameters for Ductility and Strength of Weld Bead Formed Between Aluminum Alloys Al 6061 and Al 5052", the authors, D Bahar, K Vittal Goud, K Sengameshwar and A Naresh, have carried out experiments by applying Taguchi Technique and gray relational analysis in order to optimize the percentage elongation and Ultimate Tensile Strength (UTS) of weld bead between aluminium alloys Al 6061 and Al 5052 specimen welded by TIG welding. The authors have proposed that welding current should be as high as 190 A, root gap should be medium around 2 mm and welding speed of around 120 mm/min, as well as low gas flow rate of 19 mm3/min to optimize the percentage elongation (ductility) and UTS.

Air-cooled engines are the only option for two-wheelers due to some advantages like lighter weight and lesser space requirement. An air-cooled engine releases heat into the atmosphere by means of forced convection by providing fins on the outer surface of the cylinder. The 250cc engine cylinder is one of the major automobile components subjected to high temperature variations and thermal stresses. In the paper, "Design and Thermal Analysis of 250cc Engine Cylinder Fin Using Different Material on Ansys Software: A Review", the authors, K R Gawande and Sameer Mahamandre, have reviewed various aspects of the design consideration of 250cc engine. The parameters considered in their review include various types of fins and cooling systems.

S V Srirama Rao
Consulting Editor

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Article   Price (₹) Buy
Numerical Investigation of Heat Transfer Enhancement in Double Pipe Counterflow Heat Exchanger Fitted with Triangular Ribs and Spring as Inserts
50
Understanding the Performance Degradation of Small Stall-Regulated Wind Turbines Due to Typical Manufacturing Defects
50
Optimization of TIG Welding Process Parameters for Ductility and Strength of Weld Bead Formed Between Aluminum Alloys Al 6061 and Al 5052
50
Design and Thermal Analysis of 250cc Engine Cylinder Fin Using Different Materials on ANSYS Software: A Review
50
     
Contents : (Feb' 2020)

Numerical Investigation of Heat Transfer Enhancement in Double Pipe Counterflow Heat Exchanger Fitted with Triangular Ribs and Spring as Inserts
Parinam Anuradha, Mohd. Ahmad and Gourav Gupta

The paper investigates heat transfer and friction loss characteristics of concentric pipe counterflow heat exchanger with plain pipe and with various arrangements of turbulators. It presents two configurations of in-line Inner Side Triangular Ribs (ISTR) on both outer and inner pipe and two configurations of helical spring wrapped over inner pipe. The effect of different parameters of the triangular ribs and helical spring at constant velocity of cold fluid of 0.05 m/s with varying velocity of hot fluid from 0.48 to 0.98 m/s was studied numerically for Reynolds number (Re) ranging from 6,000 to 16,000. It is found that the turbulators inserted inside heat exchanger increase the Nusselt number for the triangular rib arrangements up to 1.7 times and for spring arrangement up to 1.3 times over the tube without turbulator. A new combination of ISTR of ei/Hi = 0.105, eo/Ho = 0.097 with wrapped helical spring of p/d = 1.28 turbulators on the inner pipe was also studied. The numerical results revealed that the increment of Nusselt number with combined in-line triangular rib and helical spring as insert as compared to plain tube varied from 73% to 77% and this combined arrangement also provided a significant improvement of heat transfer rates over using spring or rib alone. Over the range of Re considered, the maximum values of Performance Evaluation Criterion (PEC) were found to be 1.18 for a combination of triangular ribs and helical spring.


© 2020 IUP. All Rights Reserved.

Article Price : Rs.50

Understanding the Performance Degradation of Small Stall-Regulated Wind Turbines Due to Typical Manufacturing Defects
Amool Raina, Kyle Wetzel and Saeed Farokhi

A computational flow simulation is conducted to study the underperformance of some stall-regulated wind turbine blades. A hypothesis was proposed explaining the causes for the underperformance of an 8 kW stall-regulated wind turbine machine. The two main causes affecting the performance were poor manufacturing techniques and the aerodynamic design of the airfoil. CFD studies confirmed the causes for the underperformance of these blades and a good comparison with field data was obtained for the study.


© 2020 IUP. All Rights Reserved.

Article Price : Rs.50

Optimization of TIG Welding Process Parameters for Ductility and Strength of Weld Bead Formed Between Aluminum Alloys Al 6061 and Al 5052
D Bahar, K Vittal Goud, K Sengameshwar and A Naresh

The paper aims at optimizing the percentage elongation, i.e., ductility and Ultimate Tensile Strength (UTS), of weld bead between aluminum alloys Al 6061 and Al 5052 specimens welded by Tungsten Inert Gas (TIG) welding. TIG welding process gives the operator greater control over the weld as compared to other competing processes. 16 experiments are conducted to construct L 16 orthogonal array employed in Taguchi Technique and Gray relational analysis. Four levels of current, gas flow rate, weld speed and root gap are considered in the Design of Experiment (DOE). Analysis of Variance (ANOVA), Signal-to-Noise (S/N) ratio and graphical main effect plots have been used to study the effects of welding parameters on ductility and UTS of weld bead. From the analysis, it is found that welding speed and gas flow rate should be low to enhance the ductility and current should be high to augment the UTS of the weld bead. Confirmatory test is conducted to validate the optimum parameters.


© 2020 IUP. All Rights Reserved.

Article Price : Rs.50

Design and Thermal Analysis of 250cc Engine Cylinder Fin Using Different Materials on ANSYS Software: A Review
K R Gawande and Sameer Mahamandre

The 250cc engine is a well-known mechanical component used for power generation but subjected to very high temperature and thermal stresses. Therefore, cooling of engine is essential. For this purpose, there are two options, i.e., using either liquid cooling system or air cooling system. Nowadays, many of the automotive industries prefer liquid cooling system for higher cc engine, but this system has some drawbacks which can be overcome using air-cooling system (fins). An air-cooled engine releases heat to the atmosphere through the mode of forced convection; to facilitate this, fins are provided on the outer surface of the cylinder. The paper reviews the design and thermal analysis of 250cc engine cylinder fins using different materials to replace liquid cooling system.


© 2020 IUP. All Rights Reserved.

Article Price : Rs.50

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