نشریه فناوری در مهندسی هوافضا
سال دوم شماره 1 (پیاپی 4، بهار 1397)

Nowadays efforts for development of the scramjet engines are increased. Scramjet engines use atmospheric oxygen as an oxidizer therefore they don’t need oxidizer tanks, thus the weight of these systems is less than comparable rocket systems. Success of the air-breathing engines depends on the proper air-fuel mixing. In the case of hypersonic vehicles, air-fuel mixing issues increases. Sufficient mixing between the supersonic airstream and the fuel jet is critical for the design of scramjet engines. Air velocities in the scramjet combustors are in the order of the thousands meters per second and so the residence time for the fuel to mix with air is very short. In current study, two-dimensional flowfield of the jet injection into the supersonic flow investigate numerically using Fluent software. Two-dimensional Navier-Stokes equations and k-ω sst turbulence model and the perfect gas equation are solved numerically. The results of the numerical solution are compared and validated with experimental data.

The key to maximizing power and improving engine performance during the mid-term is to use the turbocharged system on these engines. The turbulent system is a process that is performed by installing or increasing the succession of compressed air by the turbocharger. Another advantage of using a humorous system is to reduce the generation of emissions from internal combustion engines. The purpose of this article is to investigate the turbulent system by turbochargers in single-step and multi-stage methods. In multi-stage fluent systems, several cooling air is used to cool the air entering the combustion chamber. A two stage feeder system is used to meet pollutant standards and diesel engines working at high altitudes at sea level, and a multi-stage feedwater system is recommended for use on aerial gasoline engines at altitudes above 10 km.

Monopropellant thruster of attitude control system is a requirement for the development and functionalization of satellites in space, which have expensive and high-tech technology. Hydrazine thrusters are currently the most widely used thrusters for guidance and control systems of re-entry and manned spacecraft. In this paper, making catalyst and preparing catalyst bed for hydrazine decomposition in low-thrust monopropellant thrusters are discussed. The combustion chamber contains catalyst granules. The catalyst volume is selected in an optimum level. Also, catalyst materials, construction techniques of the catalyst and catalyst bed, constructional considerations and requirements, and its configuration are introduced and discussed in detail.The present study is applicable. At present, the aerospace research institute is preparing the catalyst granules for use in 10 N hydrazine threshers of a space probe, and in the first stage it will be prepared at 50 cm3.

A composite is commonly defined as a combination of two or more distinct materials, to create a new material with properties that cannot be achieved by any of the components acting alone. The growing use of composites for structural applications has made a thorough understanding of the behavior of composite joints in various applications. Joints are critical elements in composite due to their stress concentration. Composite joint is one of the most important part of structure. There are different types of joint, each of them has its own pros and cons and use in various applications and environments.

One of the challenges facing satellites is the satellite thermal control process. The mission of the satellite thermal control system is maintaining the temperature of the satellite's components in the permitted temperature range during the satellite mission. Because the radiation is the only way to exchange heat in vacuum, so the surface coating of the radiators plays the most important role in this field. On the other hand, the environmental conditions of the vacuum and the satellite orbit strongly affect the external surfaces, including the radiator surface, such as ultraviolet radiation and charged particles, contamination, micrometeoroids and the erosion of atomic oxygen. This research aims to guide and facilitate the selection of radiator coating for satellites with various missions, such as student satellites, Telecommunication, Weather, radio-television, research, military, etc. To fully examine the role of factors Effect on the radiator coating and the comparison between the current coatings of modern satellites.

So far, many observations have been made about the sun. And the results of each of these studies paved the way for further research. Now with the advent of science and technology, the "solar orbiter" is scheduled to be sent to the Sun in 2019. The main mission of this probe is to investigate the solar wind or so-called air space. The orbiter is equipped with 10 tools.This mission is scheduled for 7 years. Scientists are hoping to answer some of their questions with the solar orbiter.