Numerical simulation of axial turbomolecular pump rotor blades

Master's thesis

Applied design trend

Abstract

In this thesis, in the field of vacuum technology, the importance, application and role of this technology in the industry and the advancement of scientific research, technical terms related to this technology, types of vacuum pumps, applications, advantages and disadvantages of each of Vacuum pumps, the importance of studying the axial turbomolecular pump and the works done in this field are presented. The main focus has been on the flow simulation methods in different regimes and the resulting results. All kinds of vane geometrical parameters affecting the fluid performance of the pump have been introduced and investigated. Also, the arrangement and the reason for the arrangement of the axial turbomolecular pump rotor blades are stated. This thesis has been realized by simulating the rotating ring disk using the finite element method and using Ansys Workbench software, as well as solving the elasticity. In this simulation and solution of elasticity, small deformation was assumed due to the low speed of rotor rotation. Then the numerical simulation of the rotor blade has been done assuming a large deformation due to the high rotation speed of the rotor, and a computer program that can predict the maximum values ??of Van Mises stress and deformation in large deformation from the elasticity solution assuming a small deformation has been prepared. In the following, two connected rotating ring disks have been analytically solved and numerically simulated. Also, the blade rows of the axial turbomolecular pump rotor have been numerically modeled and simulated. The effect of blade thickness and height on simulation results is presented. In the following, the effect of different blade profiles on the simulation results has been investigated. At the end, a new model of the rotor blade made of two materials has been presented and examined and compared with the blade made of one material. It should be noted that in parts such as the rotor disk, where the results can be presented analytically, numerical simulation has been prepared and used for validation. Analytical solution and numerical simulation have been in good agreement. Keywords: vacuum, turbomolecular pump, simulation, rotor vane, stress and strain analysis, rotating annular disk, profile It has been used in many different ways. Vacuum environments have two basic characteristics. The first feature is that it creates a clean environment with the ability to control unwanted factors that require special environments to carry out certain physical and chemical processes, and the second is that it causes fundamental changes in the physical properties of materials such as reducing the melting point and evaporation. These two features are the key to performing many scientific processes in a vacuum environment. On the other hand, the vacuum also simulates the conditions of the Earth's atmosphere. This makes it possible to perform many experiments that are vital for space travel and cannot be performed inside the Earth's atmosphere on Earth. Today, by using the above features, many processes are carried out in a vacuum environment, and the possibility of producing many high-tech products has been provided. Vacuum plays a major role in the development of electronic, chemical, medical, pharmaceutical, food, metallurgy and automotive industries. Things that have wide applications in daily life, such as solar cells, semiconductor parts such as sensors and ICs, thermal insulating glass, many cutting mechanical tools with high surface resistance, medical and sun glasses, disinfection of agricultural products, production of chemicals, welding inspection, production of computer compact discs, manufacturing of composites, manufacturing of refrigerator body, repair of cooling systems, car oil change are only examples of the wide applications of vacuum. In addition to this, the vacuum plays an important role in the fields of research and development and biotechnology, in such a way that this technology can be considered the key to achieving the field of micro and nano technologies. Considering the wide and key applications of the vacuum technology in various fields of science and industry, it is necessary to take extensive and systematic measures to localize this technology in the country. In this direction, one of the main strategies is expanding research and development to design and build systems and equipment related to this technology. In recent years, attention has been paid to vacuum technology..

          In recent years, attention to vacuum technology in the country has gradually gained its importance. High vacuum technology is widely used in the industry today and plays an effective role in most fields. Acquiring the knowledge of designing and manufacturing high vacuum equipment is one of the most important achievements of any country today. The main task in creating a vacuum environment is the responsibility of various vacuum generator pumps. In this thesis, the aim is to examine a corner of the wide world of vacuum equipment design, namely axial turbomolecular pumps. The axial turbomolecular pump is capable of creating a very high vacuum up to a pressure of (10-10) pascal. In vacuum technology, this pump is widely used in the production of high and very high vacuum for several reasons such as cleanliness, compatibility, quick start-up of the pump, the ability to predict the produced vacuum, simplicity of operation and a high degree of reliability from the operational aspect. Turbomolecular pump vanes and increasing its performance will make it possible to achieve a higher vacuum range. Therefore, in this thesis, the numerical analysis and simulation of axial turbomolecular pump rotor blades has been considered as the main goal. In this regard, the effect of various geometrical parameters such as height, thickness, and blade profile effects have been studied during simulation. It is worth mentioning that the maximum compression ratio, the maximum dimensionless speed, the maximum deformation of the vane [1] and the maximum Van Mises stress due to centrifugal effects are the main influences on the performance of the turbomolecular pump. According to the mentioned cases, an attempt has been made to find the optimal conditions to achieve maximum efficiency.

1-2- The necessity and importance of studying vacuum systems technology

In a macro category, vacuum systems are considered a subset of machinery. When vacuum systems technology is mentioned, it means the ability to design, manufacture, develop, deploy and properly maintain this group of machines. In this section, the necessity and importance of studying vacuum technology, as well as the place and relationship of this technology with other technologies, the global situation and the position of this technology in Iran will be examined. Empowering and economic are divided [1]. Vacuum technology, since its development is necessary for the prosperity of all industrial sectors and can be used in a wide range of processes and products, is included in general technologies. General technologies are usually referred to as technologies whose development is necessary for the prosperity of all industrial sectors and is not assigned to one sector of the industry. In the evaluation of each technology, the issue of technology life cycle and replacement with newer technologies is considered. In addition, the relationship of each technology with its complementary technologies is also important, because the fate of complementary technologies are dependent on each other. Knowing the value chain and dependencies and technological bottlenecks ahead is essential for long-term planning of technology development. Different types of technology always appear or become obsolete in competition with each other to meet human needs. Generic technologies, such as vacuum systems technology, are inherently non-substitutable and the need for them is constant, because vacuum-based processes always require vacuum systems. Therefore, the life cycle of this general technology has always enjoyed good growth and improvement. The evolution of vacuum systems technology is usually the result of upgrading subsystems technology, using more advanced materials and smartening. It should be noted here that a general technology such as vacuum systems does not disappear when the life cycle of a specific technology such as the image lamp production system that uses that general technology ends, but the technology continues to exist as a capability in a more advanced form in other specific technologies.