نشریه مهندسی مکانیک و ارتعاشات
سال دهم شماره 2 (پیاپی 35، تابستان 1398)

The heat pipe as superconductors can play an essential role in heat transfer According to the application, are designed in different sizes The heat pipe for heat transfer with very high thermal conductivity that heat energy by evaporation and condensation of a working fluid with minimal temperature drop pass When the heat of evaporation area is the working fluid evaporates and creates a pressure gradient in the tube The steam pressure gradient along the tube makes the move to steam condenser condenses in the condenser is, the latent heat is released. The working fluid of the heat pipe by gravity thermosyphon returns to the evaporation zone In this study the vapor and liquid inside the heat pipe is modeled thermosyphon type It is assumed that the flow is permanent and peaceful two-dimensional and volumetric forces have been ignored. In this paper, the finite volume method and SIMPLE algorithm is used. The geometry of the model with the software Gambit drawing grid and numerical calculations to using a software package Efficient called Ansys Fluent by subsidies carried out and the results with the results of a study comparing the temperature of the wall and the heat pipe in all three areas have been analyzed.

Gas and liquid transmission is a routine activity in the oil industry, powerhouses, petrochemicals and nuclear industries. The pipes are exposed to micro cracks in the inner and outer surface due to factors like corrosion and fatigue in the manufacturing process. If the aligned cracks are all over, the rapid crack growth phenomenon occurs. In this case, crack will grow at high speed along the pipe axis. In this research that has been conducted for the first time in the country, the measurement of the growth rate of the crack tip is done in two ways: High-Speed camera and timing wire system in the seamless aluminum 6063-T5 pipes. The bursting pressure of the specimens with the initial crack depth of 0.8, 1.0 and 1.2 mm are 70, 65 and 58 bar. The resulting growth rates in High-Speed camera and timing wire system is about 120 to 132 and 120 to 126 m/s. The qualitative results of this research matches well with other researches in this field in other journals.

In this study, with the assumption of uncertainty in system design variables, a robust Optimization of the Flutter velocity aeroelastic wing with high-aspect-ratio under the bending-torsion effect is examined . Therefore, the aerospace wings are firstly modeled based on the Euler-Bernoulli cantilever beam model in quasi-steady aerodynamic conditions. After validating the results, in the simulation section, by using the Runge-Kutta numerical solution and the theory of Eigenvalues, the system response time and Flutter velocity are obtained. Therefore, by choosing parameters such as bending and torsional rigidity and mass per unit wing as optimization variables the effect of uncertainty on the design variables and optimized by genetic algorithm. In addition, the values of variables before and after optimization, as well as the rate of improvement of the Flutter velocity are presented in a robust and deterministic optimization. Finally, based on the optimization results, design variables for achieving an appropriate stability structure in terms of the phenomenon Flutter is confirmed.

Explosion is fast chemical reaction that alters primary explosive material to gas. Explosion process include two general part of starting explosion and interaction between environment and explosion products. Study of plate performance and investigation elastic – plastic behavior and plate rupture is essential to determine relation of those with plate geometric parameter. Shock tube is used for modeling and simulation of loading explosion. In this paper, Experimental and FEM modeling are used to Investigation of Explosive Wave blasting on the Aluminum Plate. Simulation is done by ANSIS Autodyn software. Shock tube was designed and fabricated in order to experimental study.

One of the most suitable places for the implementation of cogeneration systems (CCHPs) are hospitals . The high and continuous of electricity, heating and cooling loads in these places have caused the use of this type of system to be of great attraction. The low tariffs for energy carriers in government hospitals have caused the private sector to refrain from investing directly in this sector due to lack of economic justification. In this study, which was performed in a typical hospital, as one of the most suitable places for construction of the CCHP system, the capacity has been estimated to 2.4 MW power plant based on two 1.2 MW gas engines. In this project, it is anticipated that by utilizing the waste heat of gas engines in the supply of heat and power to the hospital, the energy conversion efficiency could be increased from 42% to 56.4%. In this study, different solutions have been introduced in order to eliminate the obstacles of the ruler in attracting this amount of investment .

Nowadays, so much heat has been generated in data centers which is caused by many electronic devices. This generated heat has been increased proportionally with the number of racks in IT rooms .In other hands, the power consumption of IT cooling system is more than 43% of total electrical consumption in data centers, hence the technology of its cooling systems is very important. Selection of cooling system design should provide the most efficiency and the least power consumption. In this paper, data centers with raised floor or without raised floor will be considered and 9 air distribution procedures for air cooling of IT rooms will be discussed and will be compared. According to the number of IT’s racks and power consumption of IT’s cabinets, the best selection of air distribution options will be determined .by the results of this paper , the clients of data centers could choose the best cooling system options which are appropriate with the number of racks and the power heat generation in data centers.

The present study aimed to investigate the convective heat transfer coefficient of nanofluids containing magnesium oxide nanoparticles in water-based fluid in the exchanger plates have been carried out. Tests on the volume fraction of (0.005, 0.01, 0.015and 0.02) were used in this study have Ast.nanvzrh which has a diameter of 20 nm. Also the results show that with increasing fraction nanofluid volume, heat transfer coefficient and thus increases the heat transfer. Also heat transfer nanofluids% increase in volume fraction of 0.02 to 0.005 respectively 52% and 4.3% is on.