مجله مهندسی مکانیک
پیاپی 138 (امرداد و شهریور 1400)

Delta wing is studied numerically for vortex break down in different turbulent model. It is modeled with the geometry used in elder references and a high quality mesh is applied on it. The aim of this article is to study Aerodynamic coefficients for different states of the delta wing and also to study the charts of these coefficients in vortex break down mode and different turbulent model mode. The method of this study is numerical. Aerodynamic coefficient captured in this study is compared with elder studies. The results show that by increasing the angle of attack up to 35 degrees, the vortices on the wing breakdown and the performance is worsened and the turbulent model kw shows Aerodynamic behavior better than others. The innovation of this article is that vortex break down is studied in 35 degrees angle of attack and the other innovation is that, 3 vortex models is applied and considered kw is the best.

controlling of microstructural features is possible by changing of additive manufacturing process parameters. The purpose of this paper is the application investigation of manufacturing process data analysis in process parameters during manufacturing of parts. In this paper, microstructural defect such as grain misorientation is presented, and then the effect of microstructural and manufacturing parameters control on elimination of these defects is studied. In-situ controlling of microstructural features is possible by using data of thermographic imaging during the additive manufacturing process. Forecasting of microstructural and mechanical properties is possible by developing a system for gathering and analysis of manufacturing data during the process.

The aim of this study is to optimize the volume of a three-layer rotating cylinder under internal pressure and centrifugal load used in design of turbine engines compressor rotating drum. In thick-walled rotating cylinders under internal pressure, maximum hoop stress occurs in the inner radius. In compound cylinder, the hoop stress can be reduced by pressing the layers together that causes using the capacity of the outer radii to withstand stress. The stress equations of compound steel cylinder are extracted by the superposition method. Then a numerical optimization solution is proposed to minimize cylinder volume. The maximum hoop stress resulted from the optimization program is 39% less than single layer cylinder with the same condition. In order to validate, the problem is simulated in the Abaqus software. Maximum difference of 1.3% obtained from the analysis and simulation.

One of the most widely used electrical appliances is compression refrigeration systems or air conditioners, the split type of which is one of the most used air conditioners in hot areas. In such coolers, condenser plays a key role in its efficiency. The aim of this study was to investigate the effect of solar radiation and environmental factors such as temperature, humidity and wind speed on the amount of electrical energy consumption of split air conditioners. The study was conducted experimentally in spring and summer. In order to study the effect of solar radiation, three different angles have been considered for the location of the condenser, which include south latitude, 45 degrees to the left and right, as well as east in the morning and west in the afternoon. The results show that when the condenser is in the 90 degrees position (east-west) due to reduced radiation, the amount of energy consumption is reduced by up to 6% compared to the zero degrees angle and parallel to the south.

The supply of required cooling energy for building and industrial applications, along with simultaneous efforts to reduce environmental pollution and also reduce electricity consumption and related costs, are a concern that has been considered by researchers for years. Required cold load in most parts of Iran is higher than for heat load. In hot and humid areas where we have to use compression refrigeration systems with high power consumption, it seems more necessary to find alternative methods. In this research, a new design in the form of a cold water cycle in a copper pipe that can be installed on domestic fans has been proposed which can also significantly reduce power consumption and be able to replace the compression cooler in times of moderate temperature. The results showed that in times of moderate heat, this alternative system can be used and create similar cooling conditions with air conditioners and cusses a reduction up to 90% in electricity consumption. Also, the return on investment in this project was calculated for about one year.

This article introduces direct and indirect evaporative cooling systems. Then a special type of indirect evaporative cooling systems working based on the Maisotsenko cycle is introduced. Systems based on the Maisotsenko cycle can ideally reduce the inlet air temperature to the dew point temperature of the inlet air. The wet-bulb efficiency of these systems is higher than other indirect evaporative cooling systems. These systems can reduce energy consumption up to 90% compared to traditional ways. In the following, by classifying the different climates of Iran, the possibility of using this system in different cities of Iran has been investigated. The obtained results show that due to the different climatic conditions of cities of Iran, using these systems is not suitable for cities with high relative humidity and large difference between dry-bulb and dew point temperatures such as Rasht, Sari, Ramsar, and Ardabil.

Magnetic shape memory alloys are a subset of excitatory materials whose material shape and other mechanical properties change in response to magnetic and mechanical fields. Memorable alloys in recent years due to their unique properties such as high corrosion resistance, relatively high electrical resistivity, relatively good mechanical properties, long fatigue, high ductility and adaptability to the body in a wide range of Industries have been considered. These alloys are smart materials that can recall their original shape after deformation. The purpose of this paper is to introduce, apply and study the properties of magnetic memory materials. In fact, by presenting several studied models, structural equations, properties, their application in different fields and diagrams, we have tried to study these materials and we have discussed the existing challenges, such as the existence of asymmetric rate-dependent hysteresis with large saturations and its solution.

The power transmission system of vehicles is due to torsional fluctuations due to non-uniformity of combustion processes, which should be reduced and prevented from spreading to all units of the power transmission line. The manual transmissions do not have a vibration reduction system in themselves, so the source of the vibration must be reduced before entering the gearbox. Automakers have so far been able to partially reduce these non-uniformities in the clutch and prevent it from being transmitted to the gearbox and other transmission line components. One of the new methods that eliminates this defect to a great extent is the electronic management of the limited slip clutch, which is the result of thinking and presenting a new design by the researchers of this article, and can be the basis of many analytical works. The proposed solution, which is based on creating a limited slip based on the electronic clutch system, prevents uneven entry into the gearbox and thus does not transfer it to the structure and body of the car, which increases the comfort and relaxation of the driver and passengers. It is noteworthy that all the results recorded by the experiments and research conducted at the Research and Development Center of the Volkswagen plant in West Germany have been validated by the author.