Mechanical Engineering

Tunnels represent a key part of the world transportation system playing a fundamental role both in people and freight transportation, especially in developed countries. Around the world, most major cities and metropolitan areas have metro systems accounting for hundreds of kilometers of underground tunnels and network systems. This study presents the pressure losses in ventilation systems of a long circular tunnel using for a metro purpose length of 700m, and diameter 6.6m, K.M.R.C., Kolkata has been vividly studied and presented in this dissertation. The tunnel which is being driven in the soft soil by using a tunnel boring machine has already developed up to a length of 700m and till the excavation is going on to continue. Auxiliary ventilation is adopted to ventilate the tunnel with the help of an axial-flow fan connected to a duct of approximately 680m in length. The various ventilation related parameters, viz. air quantity, pressure and temperature of the air in various locations inside the tunnel have been studied. In addition, we emphasize the pressure losses in tunnels in various locations i.e., to consider as bend taking place has been calculated. In the Kolkata metro, there is an earth pressure balance TBM is used. EPB excavation provides continuous support to the tunnel face by balancing the earth pressure against the forward pressure of the machine, and the advancement rate is 15 meters every day. In addition, the pressure losses in various tunnel configurations have been computed from the empirical relations as well as computational fluid dynamics (CFD) simulations. The aim of this project work is to correlate the values of pressure losses of analytical results and the computational simulation results with the help of using CFD software and conclude the difference of graph plotted to assess the adequacy of the tunnel and suggest a few measures to improve the ventilation inside the tunnel for building a cordial environment and enhancing the tunneling operation. This study suggests that pressure losses in field study and CFD simulation are approximately the same.

The aim of this paper is to design and analyse a biconvex aerofoil with slightly curved leading edge and estimating the coefficient of pressure (CP), coefficient of lift (CL) and coefficient of drag (CD) at supersonic and hypersonic speeds. The aerofoil is symmetric and has a thickness of 6%. Gambit and Ansys Fluent are two best CFD software used for the analysis. The aerofoil was designed and meshed using Gambit software. Good quality boundary layer mesh can be easily generated using Gambit. The mesh generated was analyzed using Ansys Fluent software. About 1000 iterations were used for the simulation purpose. The pressure coefficient, lift coefficient and drag coefficient for the designed aerofoil were obtained. It was proven that the biconvex aerofoil can also be used for hypersonic speeds.

In this study, the producing of conical parts through backward extrusion has been numerically investigated. The finite element method has been used in order to extract the deformation behavior of 7075 aluminum alloy under this process for manufacturing of conical parts. The effect of friction on the process load has been investigated. The strain distribution has been studied and it was observed that in this process, the amount of plastic strain applied to the deforming part has reached above 2, which indicates that in this process, suitable mechanical properties can be expected from the manufactured part.

Acoustic waves have a massive potential in the realm of crack detection. Since cracks remain undetected for a long time, which may result in component damage, all sorts of methodologies which help in crack detection are considered to avoid deterioration and failure. Acoustic Emission (AE) is a critical indicator of crack initiation and propagation. Due to this, crack localization is done effectively using AE in different applications. The methodologies incorporating the acoustic waves' ability to detect and probe the crack existence is found to be practically viable and feasible. The paper makes an effort to analyze the different methodologies incorporating the AE towards the crack detection and propagation from all practical perspectives.

Pressure relief valves uncertainty and parameter variations are of major significance in the hydraulic system operations. The use of one such valve, a compound pressure relief valve is the subject of this paper. From the deduced differential equations, MATLAB/SIMULINK simulation model developed. The pressure response of a valve with damping spool pilot poppet has been investigated and compared with the experimental results. Also simulated the effects of some critical parameters on the valve dynamic performance.

This paper deals with the performance analysis and optimization of working parameters of a flat plate solar cavity collector. Cavity type configuration is an improved version of a flat plate collector. It is evident that every solar gadget need a little bit of improvement in order to perform well. Various experiments both theoretical and experimental are going on in various countries to achieve better performance of flat plate collector. Hence the better choice for the improvement of flat plate collector is the cavity collector. Usually the cavity type configuration is utilized for focusing, solar tower and Fresnel lens collectors. But it was experimented for the flat plate improvement and hence it is proved to be a one of the alternate solution for the flat plate collector. It also works more efficiently even at low radiation source for a certain period of time and at part cloudy days. Solar Cavity Collector (SCC) has been experimented with various working parameters like change of receiver material (Copper and Aluminum), various L/D ratio, change of inclination angle, change of mode of flow (parallel and serpentine), collector packed with pebble bed and metal chips to enhance the heat transfer phenomena in the collector, by increasing the number of cavities and Collector with end plates. End plates were welded at entry and exit of the receiver pipes to stagnate the water for a while inside the collector.

Wire electrical discharge machining (WEDM) own benefit in manufacturing of modern materials, particularly used in the space engineering technology as well as in therapeutic industries. With WEDM advancement, complex components can be able to cut easily those hard to machine with conventional process. Obtained high level of precision component and fine surface finish leads WEDM important, WEDM so perplexing in characteristic, as a result choice of fitting information variables is unrealistic by experimentation process. In any machining process, the machining parameters fundamentally influence quality; cost, time and production rate of a manufactured product. WEDM methodology includes more number of variables that influence its execution. However, in the illumination of the writing study and based on the previous tests, pulse on time, pulse off time, wire pressure, and water pressure are considered for the investigation. In this study, Response Surface Methodology (RSM) is utilized to show relation between the information and yield reactions by using trial information, gathered based on DOE. MRR and Ra were plotted and examined based on impact of information process parameters. Later on the created design can be used for optimization.

The concept of paper begin with a review of the salient theory and available body of literature of SCM in terms of responsibility, manufacturing practices, competitive advantages, SCM practices and overall performance of company. As the study composed of surveys of 92 manufacturing companies nearby Bhopal and in-depth interviews is discussed and their findings shared. Various statistical tools are used for the analysis of collected data. Their reliability and content are checked using reliability analysis. The discussion of findings and their implications, and concluded with some suggestions for future research.

Recently, massive interest was paid to new technologies dealing with environmental aspect. Perpetuation of natural resources such as natural fibre reinforced polymeric composite leads the upcoming manufacturing industry to search and scrutinize eco-friendly materials. The use of composites in manufacturing equipment and products is taking a very important space in the industry in general. Moreover these materials have unique characteristics when analyzed separately from constituents who are part of them. However, it is known that care must be taken in their manufacture, as the use of appropriate process and the composition of each element, in addition to adherence of fibre, which is a major factor in obtaining the final mechanical strength of the product. One should also take into account whether the composites are environmentally friendly. For this reason, in this work, a composite partially ecological was made, using sisal as reinforcement, which is a natural fibre with renowned mechanical properties as dispersed phase of the composite in the polypropylene resin, in quest of improving the mechanical behaviour of NFRP composite.

A computational study on performance and emission characteristics of single cylinder, four stroke SI engine operating on ethanol-gasoline blends was carried out on AVL BOOST at different compression ratios. In this paper Vibe two zone model was selected for the study of combustion analysis and simulation were carried out for different blends of ethanol and gasoline i.e. from 0% to 30% of ethanol by volume with the increment of 10. The computational results show that gasoline fuel produces more power and torque than E10, E20 and E30. Whereas there is a considerable decrease in the emission of HC and CO but NOX increases with increase in ethanol content.