Journal of Mechanical Engineering and Vibration: 5 (4)

Open Access Article

1 - Effect of Obstacles Geometry on Temperature Variations of a Flowing Fluid in an Open Channel – Experimental Investigation and Numerical Modelling
نادر رهبر Mahdi Hamzei Siavash Zabeti-Jahromi

In this paper the effect of placing various obstacles on heat transfer between the air and water in an open channel was investigated. For this purpose, seven different obstacles were placed into the water while incorporating underwater aeration and forced air movement o More

In this paper the effect of placing various obstacles on heat transfer between the air and water in an open channel was investigated. For this purpose, seven different obstacles were placed into the water while incorporating underwater aeration and forced air movement on the water, to measure input and output water temperatures at eleven different flow rates. The results indicated that placing an obstacle in the channel is associated with an increase in heat transfer from the water. Furthermore, the highest rate of heat transfer was achieved when there was a forced convection of air on water. Under natural convection, the highest rate of heat transfer was observed for the turbulent flow up to middle of the channel, while under forced convection, it was observed in forced air movement on water surface. Also in this research, open channel flow was numerically simulated in Fluent software via RSM model. A Comparison between the numerical results and experimental data may indicate the ability of Fluent software in accurate flow simulation in the open channel. Manuscript profile

Open Access Article

2 - Sock behavior study in flow around pitching airfoil in transonic regime
Ali Heydari

In this study, solution of unsteady flows with moving boundaries is considered. So that two dimensional inviscid unsteady and incompressible flow around an oscillating airfoil is investigated by solving Euler equation using structured adaptive grid network. An adaptive More

In this study, solution of unsteady flows with moving boundaries is considered. So that two dimensional inviscid unsteady and incompressible flow around an oscillating airfoil is investigated by solving Euler equation using structured adaptive grid network. An adaptive grid is produced using linear spring network, which can be attached to the surface of the object and modeled moving surface. The work initially focused on production of adaptive spring grid network and different state of adaptive grid production is investigated. After investigations of mesh and time step independency, the results are compare with experiments. Also, to show the advantages of structured adaptive grid network, the results are compared with unstructured adaptive grid network. The results show that use of adaptive structured network leads to increasing the speed of solution while maintaining the accuracy. Also it can be seen that in pitching airfoil, the shock behavior depends on the direction of movement, instant angle and mean angle of oscillation. Manuscript profile

Open Access Article

3 - Investigation of energy absorption in shock absorbers of grooved circular using response surface
شیما شهروی محمد جواد رضوانی علی جهان

The main objective of this research is improving the design and performance of the polyurethane foam-filled thin-walled aluminum grooved circular tubes. The tubes are shaped with the inner and the outer circular grooves at different positions along the axis. In this stu More

The main objective of this research is improving the design and performance of the polyurethane foam-filled thin-walled aluminum grooved circular tubes. The tubes are shaped with the inner and the outer circular grooves at different positions along the axis. In this study, the effects of the grooves distance, tube diameter, grooves depth, foam density, and tube thickness are investigated on the Specific Energy Absorption (SEA) of grooved circular tubes. finite-element analysis (FEA) and response surface methodology (RSM) is carried out for crush force efficiency. Finite-element analysis is performed with design of experiments technique (DOE) at the different combinations of the design parameters. The results of RSM indicate that SEA is related to the grooves distance, tube diameter, tube thickness of the groove and groove depth, by a quadratic model. Moreover, the effects of the interaction between the grooves distance - the foam density and the grooves distance - the tube diameter on the SEA was significant. Manuscript profile

Open Access Article

4 - Modeling of MED distillation with vapor compression
ashkan hamedi Hadi Kargar Sharifabad

Due to the ever-increasing human need for drinking water and limitation of available drinking water resources, we always need to use salty waters of the seas and oceans for converting into purified drinking water. In the article, a variety of water treatment processes i More

Due to the ever-increasing human need for drinking water and limitation of available drinking water resources, we always need to use salty waters of the seas and oceans for converting into purified drinking water. In the article, a variety of water treatment processes is reviewed and applied. In all the processes, energy must be used for the preparation of purified water. Since the resources for available energy are also limited, the researchers always attempt to identify the best method for water purification in terms of cost, energy consumption and the other items. Also, with thermo-economic analysis, they cause the cost of drinking water is minimized. Among a variety of Multi Effect Desalination methods, Multi Effect Desalination with Parallel Feed along with Steam Ejector is analyzed thermo-economically. Moreover, the conditions are investigated in that we can have less cost for purified water. Finally, we will observe that in Multi Effect Desalination methods, Steam Ejector reduces the cost up to 60%. In Multi Effect Desalination refineries, even if the temperature of salt water in the first stage is 70°-80°, Steam Ejector will cause to produce most purified water. Manuscript profile

Open Access Article

5 - Numerical simulation and experimental study on a microscale vortex tube
نادر رهبر Mostafa Shateri Mohsan Taherian محمد صادق ولی پور

In This paper the energy separation phenomenon in a micro-scale vortex tube was investigated by using the computational fluid dynamic. The flow is assumed as steady, turbulent, compressible ideal gas, and the shear-stress transport is used for modeling of turbulence phe More

In This paper the energy separation phenomenon in a micro-scale vortex tube was investigated by using the computational fluid dynamic. The flow is assumed as steady, turbulent, compressible ideal gas, and the shear-stress transport is used for modeling of turbulence phenomenon. The results show that 3-D CFD simulation is more accurate than 2-D axisymmetric one. Moreover, optimum cold-mass ratios to maximize the refrigeration-power and isentropic-efficiency are evaluated. The results of static temperature, velocity magnitude and pressure distributions show that the temperature-separation in the micro-scale vortex tube is a function of kinetic-energy variation and air-expansion in the radial direction. Manuscript profile

Open Access Article

6 - Atomistic simulations on the influence of diameter, number of walls, interlayer distance and temperature on the mechanical properties of MWBNNTs
mohammad reza mostafaei Abdolhosein Fereidoon Masoud Darvish ganji

By using molecular dynamics (MD) simulation the mechanical properties of single, double and triple walled BNNTs (SWBNNT, DWBNNT and TWBNNT) is investigated. The effects of diameter, chirality, interlayer distance and temperature on the mechanical properties of respected More

By using molecular dynamics (MD) simulation the mechanical properties of single, double and triple walled BNNTs (SWBNNT, DWBNNT and TWBNNT) is investigated. The effects of diameter, chirality, interlayer distance and temperature on the mechanical properties of respected systems have been investigated. The results showed that, zigzag BNNTs are stiffer than armchair ones with nearly the same diameter. Also, the Young’s modulus of both type of DWBNNTs and TWBNNT increase when the tube diameter increases. In addition, the results confirmed that all measured mechanical properties decrease with increasing temperature. Furthermore, the Young’s modulus of DWBNNTs are smaller than TWBNNTs and larger than SWBNNT. We showed that the Young’s modulus of DWCNTs with various interlayer distances increase when separation wall distances were decreased. Our simulation findings afford not only a molecular level understanding of the BNNTs but also may be instructive to mechanical engineers and scientists who attempt to develop effective mechanical properties. Manuscript profile

Open Access Article

7 - RSM in Analysis of Energy Absorption of thin-walled conical groove tubes filled with polyurethane foam
بتول سرکبیری علی جهان محمد جواد رضوانی

AbstractEnergy absorbers are used in various – especially in the automotive – industries as a solution to reduce the damages stroke on the passengers, and to enhance automobile safety. Nowadays, thin-walled tubes as one of the most efficient energy absorptio More

AbstractEnergy absorbers are used in various – especially in the automotive – industries as a solution to reduce the damages stroke on the passengers, and to enhance automobile safety. Nowadays, thin-walled tubes as one of the most efficient energy absorption systems have found increasing applications. In this study, energy absorption parameters is performed to investigate the impacts of designing variables related to thin-walled conical groove tubes using finite element analysis. However, since the output of these studies depends to methods of designing computational experiments, the design of experiments technique (DOE) is used in this study along with the finite element analysis. For this purpose a conical aluminium tube filled with polyurethane foam is simulated that the grooves are designed with a given distance on the inside and outside surfaces under quasi-static load. Objectives of the design include the specific energy absorption e (SEA), and designing variables including conical angle, grooves distance, foam density, groove depth, and tube thickness. response surface methodology (RSM) showed that the tube thickness foam density, groove depth and grooves distance, respectively and linearly relate to the amount of specific energy absorption These results can be helpful in the design of thin-walled tubes with different conical geometries. Manuscript profile

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