Computer–Aided Design of the Critical Speed of Shafts

A computer aided design software for the analysis of the critical speed of shaft, is developed and presented in this work. The software was designed using the principles of object oriented programming, and implemented with the Microsoft Visual Basic Language. The package was tested on a number of benchmark design problems. The solutions obtained were highly accurate. Also, the software exhibited very high efficiency. To improveon the method of presenting these solutions, graphical features were incorporated. This enhances the ability to visualize results

Design and Construction of a Scroll Compressor of an Automobile Air Conditioning System

This work focuses on the design and manufacture of a scroll compressor used in an automobile air conditioning system. A scroll compressor is a positive-displacement machine that compresses air with two interfitting spiral shaped scroll members. This compressor is of semi-hermetic design, and is quiet, reliable and efficient in performanc

Analysis of pressure variation of fluid in bounded circular reservoirs under the “No Flow” outer boundary condition

Predicting the pressure at the wellbore in bounded circular reservoir has been the hub in the study of Reservoir Engineering. Predicting the pressures outside the reservoir was not an easy task. The Ei function method has been the only method for determining the pressure outside the wellbore of a bounded circular reservoir. The disadvantage of the Ei function method is that it involves rigorous iterations. This study sorts to use another approach to determine the pressure within and outside the wellbore at a glance. The finite element method was used in this study. The reservoir domain was divided into smaller subdomains and analysed. The results from these subdomains were assembled to represent pressure in the entire reservoir. The results obtained where shown tabular form (dimensionless pressure and dimensionless time) for dimensionless radii of 1.5, 2, 2.5, 3, 3.5, 4, 5, 6, 7, 8, 9, and 10. It was shown that the relationship between dimensionless pressure and dimensionless time was linear. The result obtained at the wellbore was compared with the results obtained by Van Everdigen and Hurst. It was shown that there was a  strong positive correlation between the results.Keywords: Bounded circular reservoir, constant terminal rate, dimensionless variables, diffusivity equation, and Crank-Nicholson scheme. Nomenclatur

ANALYSIS OF PRESSURE VARIATION OF FLUID IN AN INFINITE ACTING RESERVOIR

In this work, we investigate the well pressure distribution in a boundless reservoir.  This research work seeks to know the pressure variation in a reservoir whose pressure disturbance caused by the withdrawal of fluid from the wellbore, is yet to be felt at the external boundaries of the reservoir. The diffusivity equation was used in the analysis. The work covers the transient state where the reservoir is acting as if it was infinite in size. The finite element technique, using Lagrange quadratic shape elements was employed to carry out the analysis over the cross-section of the reservoir. The analysis was done with the assumption that before the well begins production, there was uniform distribution of pressure all through the reservoir. The accuracy of the result was validated by comparing with the results published by Chatas and Lee. The comparison shows a strong positive correlation between the two methods. Also, the results published by Chatas and Lee stated only the pressure at the wellbore at a particular time but this work predicts the pressure variation in the entire reservoir from the wellbore to the infinite sized external boundary at the same time.  http://dx.doi.org/10.4314/njt.v36i1.1

A Genetic algorithm for evaluating the zeros (roots) of polynomial functions, optimizing and solving n-dimensional systems of equations

This paper presents a Genetic Algorithm software (which is a computational, search technique) for finding the zeros (roots) of any given polynomial function, and optimizing and solving N-dimensional systems of equations. The software is particularly useful since most of the classic schemes are not all embracing. For example; Newton-Raphson Scheme can only solve the zeros (roots) of polynomial, while and Gauss-Jordan scheme can only solve set of linear simultaneous equations. This characteristics of classical schemes, thus pose a limitation to the scope of problems they can they can used to solve. This limitation is effectively and accurately easily resolved using the genetic algorithm programme. It is demonstrated using a number of examples . Thus it solves a wider class of optimization problems, and also solves for the zeros or roots of polynomial. The program was designed and implemented using Microsoft Visual Basic object oriented programming Language. JONAMP Vol. 11 2007: pp. 213-22

Finite element solution of the Boussinesq wave equation

In this work, we investigate a Boussinesq-type flow model for nonlinear dispersive waves by developing a computational model based on the finite element discretisation technique. Hermite interpolation functions were used to interpolate approximation elements. The system is modeled using a time dependent equation. Solution to the model is obtained, through a combination of two different schemes namely: a time approximation scheme (the Newmark Method) and the eigenvalue finite element method. Using this schemes, discrete solutions of the model at different time steps, were obtained. Graphical illustrations of solutions for the transient displacements at the center and right end of the rod are presented. The results obtained are very accurate and the model efficient. JONAMP Vol. 11 2007: pp. 223-23

Radial flow of slightly compressible fluids: A finite element-finite differences approach

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Application of finite element-elgenvale method in the determination of transient temperature field in functionally graded materials

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Numerical Modeling of a Rayleigh Step and Multi Step Slider Bearings using Finite Difference Method

The oil film pressure in a step slider bearing is difficult to obtain because the discontinuous clearance leads to a discontinuous velocity profile. In this paper, the pressure distribution in a step slider bearing is obtained numerically by introducing a virtual clearance to satisfy the continuity of the velocity at the step. The governing equation is discretized using central difference method for each internal node in the flow volume and the resulting system of equations solved using Gauss Seidel scheme with a convergence criterion of 0.0001. The result obtained with the present method is in good agreement with analytical solution for the Rayleigh step slider. The method is also applied to a multi step slider bearing for which no analytical solution exists. The solution converges when the mesh is refined

Analysis of Tube Drawing Process – A Finite Element Approach

In this paper the effect of die semi angle on drawing load in cold tube drawing has been investigated numerically using the finite element method. The equation governing the stress distribution was derived and solved using Galerkin finite element method. An isoparametric formulation for the governing equation was utilized along with C0 cubic isoparametric element. Numerical experimentation showed that the results obtained using the present method is admirable close to the analytical solution and more accurate than finite difference solution. Having established the accuracy of the present solution method, parametric studies were carried out to show the effect of die semi angle on the drawing load for different tube drawing processes. The analysis was carried out using a Visual Basic.Net program developed by the authors. The results are presented in both graphical and tabular forms