JOURNAL OF FACULTY OF ENGINEERING (UNIVERSITY OF TABRIZ)
Year:2002 | Volume:27 | Issue:27|Papers Count:7

Details of a numerical model for simulation of the turbulent flow within a square river harbour are discussed. The turbulent flow has been modeled using the depth-integrated hydrodynamics Reynolds equations. The finite difference scheme has been used to discretize of the governing equations and they have been solved using the ADI method and Thomas algorithm. In the current study, we tried to apply the zero and two equation turbulence models (i.e. the mixing length and k-e) and the different closed boundary conditions so that we can get the exact flow pattern within the harbour as far as possible.

In this study, perforated steel plates are proposed to reinforce concrete slabs. Three slab specimens reinforced with perforated steel plates and three slab specimens reinforced conventionally were cast and tested to failure. Test results and analysis show that slabs reinforced with perforated plates provide higher cracking strength, ductility, energy absorption capacity and ultimate strength than slabs reinforced with conventional reinforcement. Improve in force transfer between steel and concrete can facilitate the use of perforated plates in various applications, specially those made of composite materials with high tensile strength.

The Boundary Element Method (BEM) with linear and quadratic shape function is applied to numerical simulation of solidification and cooling processes of pure metal in the area of casting produced in a sand mould with different boundary conditions. In BEM, nodal points are located only on the boundary and move together with the phase change interface. The governing transient heat conduction equation is solved using a BEM with time dependent Green’s function and convolution integrals to determine the temperature distribution. The boundary energy equation (Stefan condition) is used to predict the movement of the solidification front. The accuracy of the method is illustrated through one-dimensional numerical examples. Some accurate experiments were carried out to obtain cooling curves, using the facilities of the University of Birmingham, England. Results from numerical simulation and experiment are compared and discussed. Agreement between simulated and measured temperature histories is good.

In gasification and combustion of biomass including wood, the main problem is the transfer of alkali compounds on the surfaces of the energy systems. The deposition of these compounds on the surfaces may lead to erosion and corrosion of surfaces as well as flow blockage and vibrations. In this paper the gasification and combustion of wood particles in cyclone gasifiers are simulated and the parameters that affect on the reduction of alkali compound transfer to energy systems are studied. The Euelerian conservation equations of the gas phase are solved using the control volume approach and the Lagrangian equations of motion of solid particles are solved by a step-wise integration. The verifying of results including the distributions of temperature and chemical species, devolatilization time, particle trajectory and residence time of wood particles shows that the equivalence ratios ranging from 0.15 to 0.4 and particle sizes from 150 to 600 microns, provide satisfactory conditions for reduction alkali compounds and effective combustion of particles. Comparisons between predicted and measured results show good agreement.

Occurrence of singularity in robot manipulators complicates control process of the robots. Suitable design of robot’s trajectories is one of the ways for prevailing over the effects of singularity. In this article a new method for determining feasible trajectories along singular direction that a robot can leave a singular point at the beginning of its trajectory, is presented. On the base of singular value decomposition and mathematical model of singularity, an algorithm is presented for nonredundant robots in singularity with rank deficiency one, to find feasible trajectories along singular direction. Then the results were applied to a six degree of freedom robot and its feasible trajectories are determined.

Francis turbines are one of the most popular turbines used in hydraulic power plants. In this paper, several relations are introduced to determine the approximate shape of the turbine runner and then the fluid flows inside the runner as well as the draft tube are numerically simulated. First, an approximate shape for the runner passage (i.e. hub and shroud profiles) is determined which is based on experimental data and then using the provided data for H, Q and N the runner blades are designed. Flow simulations are based on the 3D Solution of the Navier-Stokes equations for incompressible turbulent flows. A commercially a vailable CDF code is used for the numerical simulation. The numerical results for flows inside the turbine runner and the tube indicate the capability of the code for such flow simulations and show that such utilities could be used to numerically investigate complicated phenomena such as cavitation and separation inside turbomachines. In addition, these CFD codes could be used in shape optimization for turbine blades.

To find out potential of Uromia lake , chemical and physical properties of water have been determine in spring and fall to various depth and parts of the lake. The results which have carried out based on t-test, Hotelling T² test and discriminate analysis, confirmed that in spring concentration of lake water is hetrogenous but in fall concentration of lake water is homogenous and this causes a great mass transfer between mentioned zones which in return can affect on some side processes like; environmental aspects, construction of Shahid Kalantary highway and bridge which is being built on Uromia lake. In addition, corrosion effect of lake water carried out. Complete studies have carried out to evaluate effect of fractional crystallisatin processes on lake water.