نشریه مهندسی مکانیک و ارتعاشات
سال هفتم شماره 3 (پیاپی 24، پاییز 1395)

Always considering the scientific community as well as various industries including electronics industries to find new techniques to increase the heat transfer rate. The use of a porous media due to increase the effective surface provides a new window in this context. Therefore, in this study we are trying to find the optimal length for porous fin. In this study the effect of heat convection considered on a rectangular fin. Porous fin allows fluid to flow through and cause a better Natural Convection and Heat Transfer between them. Darcy Models have been applied to formulate Heat Transfer which is presented as a second order nonlinear equation. Geometry and porosity are classified with a Dimensionless Parameter. Thermal behaviors of Fins on Temperature Reduction including: long fin, finite-length fin with insulated tip, finite-length fin with known Convective Coefficient at the tip and finite-length fin with known temperature at the tip are found. Amount of Temperature Reduction and heat transfer are calculated.

The purpose of this article, in order to determine the impact of this type of attraction is thin-walled tubes as energy absorbing system. The twin-tube models after applying a force inside each sink. So, in order to achieve this goal and pipes of different diameters of pipe rings and simple tube, The thickness of the ring pipes and tubes, all with the impact of foam on bumpers are considered on cylindrical tube. Therefore, using numerical simulations by Abaqus software to evaluate the impact parameters, including Specific Energy Absorption (SEA) and Crush Force Efficiency (CFE) as discussed testing purposes. The energy absorbing system can be used in the aerospace industry, shipbuilding, automotive, railway industry and elevators used to absorb impact energy. Finally, appropriate geometric parameters and the best examples of criteria considered with respect to the objectives, are introduced

electromagnetic force is One of the fundamental forces and it is widely used in industry . the use of the electromagnetic force is different for example it can use for Electric engine , Contactor , etc. if it increase can use electromagnetic force in Forming , assemble, welding and Acceleration . Acceleration and To speed up of thing is newest Application , when object is in intense field and magnetic moment that is causing the acceleration and speed So this energy is Clean and quite for use to acceleration of airplane , projectile and etc. to do this research at first electromagnetic source was build then with study about effective parameters, chose wire diameter , length of coil , number of layer and tube material .use final element method (J-Mag and Abaqus ) for parameters impact on the theory. The final element test and experimental test had a good match. For analysis the output( velocity ) use minitab program. As result the coil with maximum layer and 150 mm length with wire diameter 2 is the best coil and high speed was achive with this coil and it about 431m/s.

Choosing appropriate objective function is necessary for detection of damage location and severity. To this end, objective functions based on modal parameters such as mode shapes and natural frequencies are combined with other objective functions capable to detect damage location. Then the location and severity of damage is obtained using optimization techniques. In this paper a cantilever beam is simulated numerically in MATLAB software using finite element method and then single and multi-objective genetic algorithms with different objective functions based on modal parameters are used to detect damage location and severity. To compare different objective functions, the effect of coordinate incompleteness, frequency range of interest and also environmental noise on the obtained results is studied.

Paying attention to using systems with higher efficiency in buildings is increasingly necessary due to high energy consumption in buildings and lack of energy sources. On the other hand, air conditioning systems and cooling equipment accounted for the largest percentage of building energy consumption. In this study some changes in direct evaporative cooling has been performed to reduce energy and water consumptions. A rotary cylindrical channel is assumed instead of the fixed evaporating chamber. Thus the pump is eliminated and the heat transfer coefficient is enhanced due to rotational water flow. The results are evaluated by changing input parameters such as different input speeds and different rotational speeds. The energy analysis is done and the effects of input parameters are investigated on cooling capacity, dew point effective, coefficient of performance and exergy loss.

Sheet hydroforming process has been come very common between sheet metal forming methods due to some advantages like better surface quality of products, more drawing ratio, less needing to secondary operation etc. Titanium and Titanium alloys are very applicable not only due to high ratio of strength to weight but also because of ability to tolerate work in elevated temperature. In this paper, sheet hydroforming process has been simulated using finite element method. Different parameters like effect of blank holding force, strain rate or ram speed, temperature, fluid pressue, thickness distribution etc have been analyzed. A sheet hydroforming setup based on simulation studies has been designed and fabricated. Setup has been tested for different metals and alloys especially for Titanium. Setup has ability to measure ram speed, blank holding force, total forming load and all the parameters. A good agreement has been found by comparison between simulation and experimental results. Finally, material characterization for sheet hydroformed products has been presented.

Heat transfer used is one of the most important and applicable natural phenomenon. Heat exchangers are the must applicable member in the chemical process and we can consider them in lots of industrial units. That provided the hat energy transfer between two or several fluid with different temperature. This operation can be done between liquid – liquid, gas - gas and gas - liquid. Heat exchanger will be used in order to cooling hot fluid and heating fluid with lower temperature or both of them. Many industries are acting in design kind of heat exchanger and many field with difference names in heat exchangers design are submitted by college and university. In this dissertation, heat transfer of heat exchanger shell and tube is simulated that it is U figure and the geometric of heat exchanger has been plotted and are meshed in GAMBIT software then are analyze in ANSYS FLUENT software. Finally the obtained answers are compare with designer is answers that have obtained in ASPEN software. The flow kind has been three-dimensional and turbulence that it has been used of turbulence model kω-sst. That should be noted the heat exchanger has been simulated by single phase.

In this numerical case study, thermal and hydrodynamic behavior of Ferro fluid (water + %2 Fe2O3) in two dimension channel in present of magnetic field has been study by single phase model and finite volume method. Magneto hydrodynamic effect and then impact of adding magnetic Nano and effect of non-uniform magnetic field on fluid has been study. channel’s wall are on constant temperature of 290 kelvin and main fluid inter the channel in 340 K. four magnetic dipole place along channel and the placed the fluid under magnetic field strength of 0.1,0.15,0.2,0.25 .impact of these magnetic field on velocity, pressure, heat transfer rate and Nusselt number studied and it showed very little impact heat transfer enhancement under magnetic field and can be negligible.