Mechanical Engineering Technologies and Applications

Nonlinear formulations of the Element-Free Galerkin Method (EFGM) are presented for the large deformation analysis of Ogden’s hyperelastic materials, which are considered incompressible. The EFGM requires no explicit mesh in computation and therefore avoids mesh distortion difficulties. In this study, the implementation of the Moving Least Squares (MLS) approximation with the quartic spline weight function is used to obtain the shape function and the transformation method is proposed to impose the essential boundary conditions. Numerical results for a typical example show that the present method is effective in dealing with large deformation hyperelastic materials problems. 

Plunge pools are a very economical means of discharging high energy flows downstream of dams. However, the high energy discharge usually falls down from a considerable height with high velocity, which leads to the phenomenon of erosion due to the detachment and transport of solid particles by hydraulic forces. This pathology which is common in earth structures can lead to their failure, therefore, the understanding and the prediction of this risk are of paramount importance. In this study, a 3D numerical modeling with the LS-DYNA commercial code was developed using a coupled SPH-FEM method (Smoothed Particle Hydrodynamics (SPH) and Finite element method (FEM)) to simulate the hydraulic behavior of a physical model Ski-Jump Spillway with dentates. The water flow in the tunnels and on the ski jumps, as well as the trajectories of the jets and the impact zones could be determined for several study cases. Several examples of validation, taken from the literature, demonstrate the precision and reliability of developed numerical models. 

The main issue of internal combustion (IC) engines is efficiency. Engine inlet systems should be carefully designed to provide an optimum flow to the cylinder. Inlet manifold design is one of the ways to increase efficiency. This study focuses on improving the inlet system of an LPG-H2 fueled engine by adding a static inclined blade turbine. It is a horizontal rotational axis turbine with four blades evenly distributed with an angle of inclination of 35°. Computational Fluid Dynamics (CFD) simulations are used in order to capture the in-cylinder flow motion and its influence on the flow characteristics. The method is assessed by application to flow calculations in the intake manifold for 3000 rpm engine speed. The percentage of supplied Hydrogen with LPG is equal to 20% in volume. The simulation results of in-cylinder turbulence kinetic energy (TKE), velocity and swirl motion were presented and discussed. Numerical results reveal significant improvements in the in-cylinder flow velocity, in-cylinder swirl motion and turbulent characteristics using an inlet system with a static swirling turbine (SST). Hence, this research found that by using a static turbine, we can improve the in-cylinder flow characteristics of the CI engine running with the LPG-20%H2 blend. 

The traditional estimation methods such as fundamental equations, conventional correlations or developing unique designs from experimental data through trial and error have limits in thermal engineering due to the complexity of problems addressed. Thereby, the purpose of the present work is to explain the effective utilization of the Artificial Neural Networks (ANN) model in heat transfer applications for thermal problems, like fouling in a heat exchanger. The application of the ANN tool with different techniques and structures shows that it is an effective and powerful tool due to its small errors in comparison with experimental data. The feed-forward network with backpropagation technique was implemented in Mechanical Engineering Technologies and Applicatithis study. Based on sensitivity analysis, the performance of the network trained was tested, validated and compared to the experimental data. The results achieved by sensitivity analysis show that ANN can be used reliably to predict fouling in a heat exchanger. 

 Nitride-based hard coatings have attracted increasing interest over the last decades for machining, and cutting tool applications, owing to their high hardness, high thermal stability, good wear, and corrosion resistance. In this work, we investigated the effect of nitrogen concentration, as a reactive gas, on the structure and properties of Zr-N coatings deposited by magnetron sputtering. The structural and morphological properties of Zr-N films were described, followed by a detailed investigation of the mechanical properties of Zr-N coatings. By varying the nitrogen percentage, the structure and the hardness of Zr-N films were evaluated in a wide range. With a rising N2 percentage, the structure changed from Zr2N at 10% N2 to a mixture of Zr2N and Zr N from 20%N2 with the NaClB1 -type structure. Insertion of nitrogen atoms on the Zr leads to significant changes in film microstructure, grain size, and surface morphology, as evidenced by x-ray diffraction, scanning electron and atom. The hardness of the films was first augmented by increasing the nitrogen percentage and take a maximum value was 22 GPa for the films deposited under 20%N2 then decreased. 

In this chapter, we have studied the problem of forced convection in a simple horizontal cylindrical pipe. Two boundary conditions are considered, uniform constant heat flux and uniform temperature. The fluid to be heated is pseudoplastic, modeled by the Ostwald law (n ≤ 1.0). A fully developed velocity profile is assumed at the pipe entrance. The energy equation is solved numerically with a simple implicit finite difference scheme. Results focus on the effects of the rheological behavior (index n), the type of heating, and the Pe number on the heat transfer coefficient (Nu) and the thermal entry length. They show an improvement in heat transfer with a decrease in the fluid-structure index (n). An increasing thermal length when Pe and/or n increase is also recorded. This may lead to a huge increase in the tube’s length when a thermal establishment is targeted. New, simple, precise, and physically indicative correlations with wide ranges of variation of the main parameters are proposed here. Their mathematical forms are chosen mainly to guide manufacturers for heat exchangers dimensioning. Scientists have also shown an interest in them as tools for validation and physical interpretation.

This chapter presents the modeling and the experimental study of a water solar collector coupled to an optimized solar still developed in order to boost freshwater production in a solar distillation system. The desalination process is currently operated under the climatological conditions of Sfax, Tunisia. To numerically simulate the water solar collector, we developed a dynamic model based on heat and mass transfer of the water solar collector. The obtained set of ordinary differential equations was converted to a set of an algebraic system of equations by the functional approximation method of orthogonal collocation. The aim of this study is to present the mathematical model and experimental study of this water solar collector. 

 In this work, we investigated the effect of film thickness on the structure and properties of Ti-N films deposited by magnetron sputtering. The structural properties of Ti-N films were described, followed by a detailed investigation into their mechanical properties by using theoretical and experimental analysis. The theoretical calculation presented the Rocksalt TiN structure with a lattice parameter of about 4.255 Å, confirmed by X-ray diffraction. The experimental analysis revealed that the structure and the hardness of TiN films varied in a wide range when increasing the film thickness. The structure morphology also changed from a rough to a dense surface and a smooth structure. The hardness and Young modulus of the TiN film reach maximum values of about 26 GPa and 445 GPa, respectively, and then decrease with increasing the film’s thickness. The theoretical values of the hardness and young modulus are in excellent agreement with those obtained for the Ti-N thick films.