JOURNAL OF SCHOOL OF ENGINEERING
Year:2001 | Volume:13 | Issue:2|Papers Count:8

The scope of this paper is to consider two-dimensional flows in a rotor-stator blade rows and to analyze their effects on each other. The control volume approach based on Jameson's technique is used to solve two-dimensional unsteady compressible Euler equations in a stage of an axial flow turbine. The computational speed. At the intersection of the domains, a slip grid technique is used. The equations are solved simultaneously for both domains. The method is used in this paper for slipping of the grid has some advantages over the other slipping techniques with regard to the accuracy and CUP time. In this technique, transferring the information from the moving mesh to the stationary mesh is done by using some imaginary cells. The cubic spline interpolation is employed in such a way that the conservation laws to be satisfied. The results obtained for an axial flow turbine in this work, are compared with other's results and good agreement is obtained. Finally, the effects of row spacing between the stator and rotor blades are considered and analyzed.

In this paper, irreversibility of a thermal energy storage system has been investigated. The system is constituted of two concentric cylinders which external cylinder has been filled with a thermal storage material while working fluid slows inside the inner tube. This system works periodically. The governing equations for fluid, wan and thermal storage material are solved numerically. Some experimental works have been conducted for verification of the numerical results. Then, effect of different parameters has been examined on the irreversibility. The results show that the aspect ratio of the cylinder has strong affect on the irreversibility. Also, the necessary number of cycles needed to bring the systems to the steady state is directly proportional to the irreversibility in thermal storage system finally, based on the obtained results some suggestions are presented to reduce the irreversibility of the systems.

Accurate analysis of shear walls and cores of tall building structure needs consideration of artificial flexure and parasitic shear in modeling. In this paper, new non-linear, strain based finite elements are proposed to overcome some of the difficulties occurring due to above mentioned parameters. Numerical comparisons are also made to show that increasing or decreasing the power of the strain functions is a key to improve the behavior of the structural modeling.

Reinforced concrete frame buildings designed before 1970, often have inadequate lateral resistance and must be assessed and upgraded. These frames in addition to low lateral resistance were poorly detailed. Their common characteristics are: 1- low reinforcement ratio in the columns, 2-discontinuous positive monet reinforcement in the beam-column joints, 3- little or no confinement in joint core, 4- lap splices in columns are typically located in the potential honge region near by floor levels. Six reinforced concrete frames by three bays (three frames at three stories and other three frames at five stories) with overall span length 13.0 m designed and analyzed under Tabas, Naghan and Manjil earthquakes. Results show high lateral displacement and sever damage in columns. Therefore these frames are not able to resist the expected probable earthquakes in most cities of Iran.

The slip-casting process and the resultant monolith are strongly dependent on the nature of the powder dispersion (powder activity, phase composition, impurity content and particle morphology). Specially, the volume loading of particle, the degree of dispersion, pH, temperature and the particle packing contribute to the microstructure of the cake. This paper will I describe results of investigation of the ability to fabricate sintered materials from I different silicon nitride powders having different properties by three method of fabrication: 1-Hot-pressing 2-Slipcasting forming followed by a natural sintering 3-Cold isostatic forming followed by a natural sintering. Evaluation is carried out on .the influence of starting powders characteristics on the forming process (green density), on the microstructural and mechanical properties of sintered materials.

This paper presents and analyses production and emission of pollutants CO, NOx and soot from experimental and CFD work undertaken on a 2 MW cylindrical furnace with changeable length. The experimental measurements are carried out using chemiluminescence and infra-red techniques to measure NOx and CO respectively. Soot mass fraction is measured gravimetrically. The predicted radial variations of temperature and pollutants at two axial cross sections and the effect of furnace length on pollutant emissions compare well with the experimental measurements. The results show that an increase in length of furnace decreases CO and soot mass fractions, but increases NO concentration up to a maximum and then decreases slowly. The results also show that the centerline profiles of pollutant concentrations reach a maximum The location of the maximum centerline CO coincides with the maximum soot location, while the location of NO peak is at more axial distance from the nozzle.

Most convective heat transfer process is characterized by two types of losses, namely: Losses due to fluid friction and those due to heat transfer across a finite temperature difference. Second low analysis seeks to minimize this loss by keeping the entropy generated to the minimum. A dimensionless entropy generation is used to evaluate this. The variation of entropy generation due to friction and heat transfer, and those of total entropy generation are studied along the duct as well as varying the diameter of pipe and velocity of fluid. The fluid under consideration has high viscosity (glycerol). Also, the variation of entropy generation, for fixed mass flux, due to velocity of fluid and diameter of pipe is studied, and optimum relation among length, diameter, and velocity are obtained.