University of Thi-Qar Journal for Engineering Sciences

In this paper, an experimental study has been conducted to show the influence of insertion converge-diverge conical turbulators fitted with rectangular fins inside a circular test tube on Nusselt number, the friction and the overall performance. The air is utilized as working fluid for Reynolds number varied 10000 to 50000. In this investigation, two improvement devices of turbulent heat transfer are utilized. One is the nozzle conical used as turbulators and fixed in the circular tube with three different values of pitch ratio (P.R=1, 1.5 and 2) and the another is rectangular fins placed at the inner surface of the conical turbulators. The conical turbulators fitted with rectangular fins are tested at pitch ratio P.R=1.0 with three different area ratios of the rectangular fins Ar=0.064, 0.106 and 0.149. The experimental results appeared that the heat transfers by using combined the conical nozzle turbulators and the rectangular fins is enhanced by about 234 % for the largest area ratio (Ar =0.149). Also, the optimal thermal performance is obtained to be larger as compared with plain tube case and the conical turbulators alone.

Due to the increase in demand for electric power and increasing population density in different regions, the application of underground cables has become widely used in transmission and distribution networks. In this paper, the thermal behavior of underground cables was studied numerically. Four types of underground cables were selected copper conductor cables with (95 mm2) and (240 mm2) and aluminum conductor cables (95mm2) and (240mm2), which are used in the power networks in Iraq. The study was carried out based on the conditions surrounding such as the ambient temperature, the thermal properties of the soil and the current capacity, its effect on the thermal behavior of the cables. The results of the numerical simulation showed that the surrounding factors and loading capacities have a direct effect on determining the temperature of the cable. In addition, the type and size of the conductor cable material have an effect on determining the current-carrying capacity of the cable where the conductor cable with a nominal cross-sectional area 240mm2 has a temperature higher than the conductor cable with nominal cross-sectional 95mm2by (8.96%) for the copper conductor and (13.68%) for the aluminum conductor at current 500A.

This study introduces numerical investigation of natural convection in metal foam heat sinks with two types of fin edges namely fillet and sharp edges. Aluminum metal foam of various pore densities (5, 10, 20 PPI) and sets of porosities ( ) are used in the simulations. The dimensions of the samples were 100 mm length, 100 mm height, 10 mm thickness and the spacing between fins were kept at 8 mm. Then the metal foam strips were installed onto an aluminum base plate (100 * 100 * 3.5 mm3). The investigation has been performed by control volume method . As well as, the energy equations are established on a principle that based on a local thermal non-equilibrium (LTNE) model in which the temperature of the fluid and the solid matrix are solved separately. The heat input was different from 4 to 30 W in numerical runs and the air was used as a working fluid. The results show that the base temperature of the heat sink is lower for the new design of edges. Therefore, the proposed approach of the heat sink has significant potential to be utilized to enhance the thermal performance of heat sinks and thereby to develop more advanced effective cooling devices and techniques. The maximum enhancement of the heat transfer coefficient with fillet profile reached 5.6% greater than fins with sharp edges

In this work, two-dimension incompressible laminar viscoelastic fluid flow in an expansion-contraction duct has been investigated numerically. The effect of expansion-contraction shape, Deborah number, Reynolds number, expansion ratio and contraction length on the flow field variables has been investigated. Four cases for the expansion-contraction duct configurations are tested, the first case is the expansion duct, the second case is the contraction-expansion duct, the third case is the triangular expansion-contraction duct and the fourth case is the two-side triangular expansion-contraction duct. The study investigated the effect of the parameters: Reynolds number (Re), Deborah number (De), contraction length and expansion ratio (ER) on the flow field variables (pressure, stresses and velocity).

The FENE-P (Finitely Extensible Nonlinear Elastic in the Peterlin approximation) viscoelastic fluid model is chosen for the modeling of viscoelastic fluid flow. The code is written in Simply Fortran 2 computer language. Numerically the momentum equations and the FENE-P model equation are solved by using the finite volume method passed on the collocated grid arrangement by using the Rhie-Chow interpolation. The power low scheme is used for the convective terms in the momentum equations, the up-wind scheme is used in the convective terms in the FENE-P model equation and the TDMA algorithm is used to solve the algebraic equations.

The results show that the expansion ratio when decreasing causes an increase in the stresses and the pressure for all the studied cases. Further, the contraction length increment playing a major effect on the increasing of the pressure. It is discovered that increasing contraction length by 50% causes an increase in the pressure by 50%. For Deborah number, the results show that Deborah number effects all variables in the flow field, where the stresses show increasing with the increasing of Deborah number at the expansion side of all the cases. Moreover, the pressure is also increased as Deborah number increase for all the cases. The expansion duct it shows that increasing Deborah number from 0 to 1 causes an increase of 1.2% of the pressure, while for the contraction-expansion duct this percentage is increased. It is shown that increasing Deborah from 0 to 0.5 causes an increasing by 5% of the pressure. Furthermore, the effect of Deborah number on the recirculation zones is to shrink their size for all the cases.

A comparison between the studied cases are presented and shows that the contraction-expansion duct has the maximum stresses and maximum required pressure, while the triangle contraction-expansion has the smallest required pressure. The limit of Deborah number gets to 1.2 in the expansion duct, while it is limited to 0.5 for the other cases.

This paper is a tamped to improve the engineering properties of gypseous soil by adding novolac polymer. The soil samples brought from the west of Karbala city with 36% of gypsum content. The research was carried out by adding a different percentage of novolac polymer (3%, 6%, 9% w/W) respectively and comparing the results with other samples treated with cement in the same percentages. The targeted engineering properties are permeability, shear strength, and collapsibility. The results showed that 3% w/W of novolac gives the best improving in collapsibility which is improved to 57.8 while 6% w/W of novolac improved both the bearing capacity and the permeability which improved to (25.2 and 86.2% ) respectively.

The main aim of the inspections is to ensure that the quality of the welds meets the design requirements and operating conditions, as well as meeting safety and reliability requirements in many industrial sectors. There are many different ways of non-destructive testing NDT are employed for checking welds. The radiographic testing RT is one of the most prevalent and widely used processes in the industry to detect both surface and subsurface defects. In recent years, industrial radiography has been well developed to be used alongside with the combination of techniques of image processing to enhance both the process of inspection and the time of operation. The RT images are often affected by some external surroundings and degraded by noises during the process of acquisition of them. The filtering process is intended to recover the original image from the corrupted one. Median filtering can be considered as an appropriate procedure since it is used by many researchers. In this paper, a comparison among four types of median filter is used to get the best one, to adopting it in welding inspection images. The peak signal to noise ratio (PSNR) and root means square error (RMSE) indexes are used to perform the quality of image filtering techniques. The results shown that the median filter is a good tool for clarification of welding defects and both adaptive median filter (AMF) and decision based median filter (DBMF) gives the best results respectively. The results obtained were consistent with the results of the engineering examination for qualified and certified welding defects inspectors

This paper aims to study the flow and heat transfer of hybrid suspension in counter flow micro channel heat exchanger (CFMCHE). In order to enhance the thermal properties of micro encapsulated phase change material (MEPCM) suspension. The hybrid suspension studied in this paper consists of nanoparticles and MEPCM particles, these particles are suspended in water as abase fluid, two types of hybrid suspension are used (Cu + MEPCM suspension) and (Al2O3+ MEPCM suspension) by n-octadecane as a PCM for both of them. The hydrodynamic and thermal characteristics of thes suspensions flow in micro channels of CFMCHE is numerically investigated. From obtained results, using of hybrid suspensions as a cooling fluid lead to modify thermal performance of a CFMCHE by increase its effectiveness but it also lead to high increasing in pressure drop. The results showed considerable enhancement in cooling effectiveness of (Al2O3 + MEPCM suspension) above of the pure PCM suspension, Nanofluids, and water. While (Cu + MEPCM suspension) showed enhancement above of the pure PCM suspension and water, but was not best effectiveness than Nanofluids. Extra increase in pressure drop in both types of hybrid suspension above are leads to reduce the overall performance compared with pure PCM suspension. Therefore its use depends on the application at which this heat exchanger is employed

The aim of this paper is to predict the hemodynamics properties of blood flow during in the Critical stenosis RCA . This paper examines pulsed , laminar blood flow through state of the right coronary artery in patient heart. Data for these case were taken from a catheter laboratory in the Thi Qar Heart Center . The case for a man born in 1957 who has one stenosis in RCA with a stenosis of 80%. A non-Newtonian blood model characterized by the Carreau equation was used, and a 3D model was used with the governing equations analyzed using the specified volumetric method. The SIMPLE algorithm has been adopted to link pressure and speed during runoff. Geometric figures are drawn using Auto CAD software and combined with FLUENT. The results showed that the speed increased significantly in the area of stenosis. Non-Newtonian viscosity increases its effect near the center of stenosis. The total pressure is equal to diastolic pressure with little increase

Numerical simulation of viscoelastic fluid flow of the upper-convected Maxwell (UCM) type by finite volume on collected grid arrangement for the steady laminar flow through the 1:4 planer expansion has been obtain for a range of Deborah numbers. The conservation equations and the constitutive equations have been solved by using the finite volume numerical method on a collected grid arrangement with using the power low scheme for the momentum equations and the upwind scheme for the constitutive equations. The solution of the non-linear algebraic equation from the discretization process was obtained by using the Tri-Diagonal Matrix Algorithm (TDMA). The solution was verified with grid refinement. It is discovered that increasing the elasticity level lead to increasing the pressure, stresses and decreases the recirculation zones, where increasing Deborah number from 0 to 1.5 causes the pressure to increase by 2.6%. The finite volume method (FVM) shows that it capable for the numerical simulation of viscoelastic fluid flow with high speed to get the final solution and low computational cost

The emission that caused by fossil fuel and the constantly increasing pollution rates made the engineers and researchers focus on using hydrogen as a fuel instead of fossil fuel. Fuel cells are one of the technologies that are widely explored all over the world. Fuel cell vehicles are environmentally friendly and use hydrogen as fuel and generate zero emissions. Optimization strategies is the best way for identify the best solution to the design problem. In this paper we will use particle swarm optimization and genetic algorithm to optimize the obtained model. The result show that case 5 is the best solution after optimization in this case the fuel consumption was 2.7668

This paper presents a particle swarm optimization algorithm (PSO) as a control strategy for the offline driving cycle to obtain the best torque distribution between the two sources: internal combustion engine (ICE) and the electric motor (EM). The purpose to minimize the fuel consumption, emissions, and maximize the state of charge of the battery for the model of power-split hybrid electric vehicles (PSHEV), while the requirements of the driving performance considered as constraints. The control strategy has been applied for the UDDS driving cycle under the Matlab Simulink software environment. The results of the value of fuel consumption compared with fuzzy logic control (FLC), the global optimization genetic algorithm (GA), and ADVISOR. After comparing, the results demonstrate the effectiveness of the (PSO) algorithm over the mentioned methods in lowering fuel consumption by 8.87% for the (FLC), 22.6% for the GA. Maximizing the state of charge of the battery by 5.6% for the ADVISOR program and closest to optimal results for FLC