Mechanical Engineering

Machining is the most important of the manufacturing processes which involves the process of removing material from a workpiece in the form of chips. Machining is necessary where tight tolerances on dimensions and finishes are required. Being such an important process in manufacturing industry, a machining process is considered for investigation in the present work. This paper presents the experimental investigations on the effects of cutting variables like Spindle speed, Feed and Depth of cut on the Material removal rate and tool wear. The experiments were conducted on AISI SI steel grade on a CNC turning machine using ceramic insert. The experiments were conducted as per the design of experiments. Initial trial experiments were conducted to fix the ranges for the control parameters. After conducting the experiments the MRR and Tool wear were measured and recorded. The effects were studied after plotting the graphs between the Input process parameters versus the responses using Design expert software. The results obtained in this study can by further used for optimizing the process parameters there by the optimized results help the operator to enhance the quality as well as machining rate

The double diffusive convection in a horizontal layer of a porous medium saturated with a Maxwell nanofluid is studied using linear and non-linear stability analyses. The modified Darcy-Maxwell model is used for the momentum equation. The model used for the Maxwell nanofluid incorporates the effects of Brownian motion and thermophoresis. The thermal energy equations include the diffusion and cross diffusion terms. The linear theory depends on normal mode technique and the onset criterion for stationary and oscillatory convection is derived analytically. The non-linear theory based on the representation of Fourier series method is used to find the transient behavior of heat and mass transports. We observe that the transient Nusselt numbers show oscillatory motion when time is small. However, when time becomes very large all the three transient Nusselt values approaches to their steady-state values.

The thermal power plants are designed based on required conditions (like quality of steam, pressure and temperature of steam e.t.c.), but actually inlet conditions are not as per the design conditions. In practical situations, when power plants are installed there are lots of constraints. This tends to reduce or increase output power and heat rate of thermal power plants. These constraints are leakages, installation errors etc. So due to these conditions, the designed power and heat rate are never achieved. Due to these variations in the power output from plants, it is always a matter of disputes. So the correction curves for power and heat rate are generated for pressure drop in extraction line 5, as a parameter at different conditions. These curves indicate that if operating conditions are vary, then power output and heat rate also vary. This paper deals with the generation of the correction curves for 120 MW thermal power plant by using computer aided software for pressure drop in extraction line 5.

The cutting forces required for machining of a material are important factors in production design that need to be evaluated carefully for newly developed materials. The cutting forces directly influence the power requirement of the machine tool, tool deflection and tool wear, among other things. In this study a computational model will be developed for prediction of cutting forces in end milling of metal matrix composites. Modeling of cutting forces in milling involves evaluation of chip load, instantaneous shear angle, strain rate and temperature dependent shear stress. The computational model will be validated against experimental data from measurements of cutting forces during end milling of composites under different conditions. The validated model will then be used to conduct a parametric study on the influence of feed rate (f), depth of cutting (a), cutting speed (v), and other cutting parameters on the cutting forces generated during the end milling of composites.

The Present research has focused on mechanical behaviour of aluminium oxide reinforced aluminium metal matrix composites. Aluminium metal matrix composites are fabricated using stir casting process by varying the reinforcement percentage volumes between 0 and 10, with 30 ?m particles size. To study the mechanical behaviour through the effect of weight percentage of aluminium oxide, the fabricated specimens are tested for the mechanical and physical properties such as tensile strength, hardness and density and these values are compared with theoretical values which are obtained through the rule of mixtures. The mechanical properties of the composites are found to be greatly influenced with increasing the percentage volume of the reinforcement. Also it was observed that the experimental values of mechanical behaviour of AMMCs are nearer to the theoretical values.

The gas solid hydrodynamic studies of a Flat plate, Conical and partitioned concave distributor is reported. The study included hydrodynamic characteristics and moving pattern of particles in the bed. One of the objective of the present work is to investigate the influence of distributor types on the performance of fluidized bed reactors using group B particles as per Geldart D,.1972. Classification Gas - solid hydrodynamic characteristics viz ; Bubble diameter Froude no , Bubble rise velocity of partitioned concave distributor are compared with the conical and flat plate distributors commonly used. The bed void age is used as the parameter for indicating the fluidization quality in selecting the final configuration of the distributor. The bed void age arrived for partitioned concave distributor are compared with the conical and flat plate distributors and results presented.

An Automobile hydraulic jack can be easily operated by a single push button provided on the dash board. The jack will be installed on both the sides of chassis according to the weight distributions of the car. Similarly it will be installed on the other side of the car. The system operates on hydraulic drive which consists of three main parts: hydraulic pump, driven by an electric motor, hydraulic cylinder to lift the vehicle. The hydraulic jacks actuate separately for either side of car as per the breakdown condition. The car gets lifted and load gets distributed on three point i.e., plunger or ram of hydraulic cylinder and two tires opposite to side which is lifted. This jack will be very useful for all the senior citizens and especially for females (ladies) who find it extremely difficult to operate the jack manually in any breakdown condition. The motive behind using hydraulic system instead of a pneumatic system is the more power produced by the system and simple in design as compared to a pneumatic design. As the hydraulic oil is incompressible so the lifting capacity is more in comparison with the pneumatic system which operates on air which is compressible.

The numerical studies are performed to examine the Micropolar fluid flow past an infinite vertical plate. Finite difference technique is used as a tool for the numerical approach. The micropolar fluid behaviour on two- dimensional unsteady flow have been considered and its nonsimilar solution have been obtained. Nonsimilar equations of the corresponding momentum, angular momentum and continuity equations are derived by employing the usual transformation. The dimensionless nonsimilar equations for momentum, angular momentum and continuity equations are solved numerically by finite difference technique. The effects on the velocity, micro rotation and the spin gradient viscosity of the various important parameters entering into the problem separately are discussed with the help of graphs.

The objective of the present study is to give a review on heat transfer characteristics of fluids in curved and straight tubes for various parameters and under different experimental conditions. The heat transfer can be increased by two techniques mainly like application of external forces or by modification in surface geometry of the fluid passages. Surface geometry modifications like bending of straight tubes into curved coils are effective and efficient method of heat transfer enhancement. In this paper, various correlations proposed based on experimental heat transfer data by earlier investigators are presented to support the enhancement in overall heat transfer coefficient in curved tube and in straight tube heat exchangers. However, comparison of experimental overall heat transfer coefficient in helical coil and straight tube heat exchangers are found to be limited in the present literature.

A simple Okra threshing machine was designed, fabricated and tested to alleviate the problems associated with Okra processing in Nigeria. It is consists mainly of five units namely, the feeding assembly, the threshing unit, separation unit, power transmission unit. The overall mean threshing and cleaning efficiencies obtained were 93.95 and 99.56% respectively. Drum speed 500rpm combine with 55mm concave clearance gave the highest Threshing efficiency of 99.99%. All speeds, concave clearance combinations gave clearing efficiency above 98%. The machine threshing and cleaning efficiencies increased with increase in drum speed and decrease with increase in concave clearance. The machine is simple to operate and maintain without formal training.