| Screw compressor has the advantages of high efficiency, low energy consumption, simple structure, low noise, simple operation, easy maintenance and so on, and plays a very important role in the compressor market. It has been gradually replaced the piston compressor in many occasions, so research on twin screw compressor is more and more important. The most critical parts of screw compressor is a pair of rotors which is parallel assembled in the casing, the profile line of rotors determines the performance of the compressor, the research on the design of rotor profile line in the domestic has a certain gap compared with the overseas. Therefore, research on rotor profile line has the extremely important theory significance and the practical value.This paper does the research on the working principle of screw compressor, and deeply analysis of the process of suction, compression and exhaust of twin screw compressor. The design principle of rotor profile line and the forming principle of rotor tooth surface are studied to prepare for the design of rotor profile. Several important parameters which have a great influence on the characteristics of screw compressor such as tooth area, tooth volume, length of contact line, leakage triangle area and closed volume are derived, and put forward the design criteria of rotor profile line in view of the influence of the working characteristics of screw compressor by these performance parameters.The traditional method of design the screw compressor rotor profile is from the female rotor profile line or male rotor profile line to design the male rotor profile line or female rotor profile line according to the envelope condition and coordinate conversion, which is the traditional sense of the positive design method, which is low efficiency; it is difficult to predict the performance of the rotor. This paper presents a new design method by using the sealing line, which can reflect the performance of the rotor profile, to design the rotor profile line, it is called the reverse design method. The male and female rotors profile line equation is derived by the formula of coordinate conversion relation and the Lewis theorem from the sealing line, and give the specific expression of rotor profile line equation which is designed by several typical line type of sealing line, which makes the rotor profile design to be convenient and efficient. The key of rotor this method is the design of sealing line, in order to design a good performance rotor profile the sealing line has to be good. Therefore, the requirements of design the sealing line is also explored by the influence of critical control points on the rotor profile line, which makes the rotor profile line design could be under control in the use of sealing line, and could targeted to adjust the sealing line. Apply the reverse design method of sealing line to design a typical profile line, which verified the method of sealing line is feasibility and correctness, finally using sealing line method to design a new rotor profile line with excellent performance.Combine the theory of the reverse design method based on sealing line which was studied in paper and the positive design method of the rotor profile line which was studied in previous to develop the twin screw compressor rotor profile design system by using the MFC module and OpenGL graphics functions in Visual Studio 2008. Using the method of grid interface and the technique of dynamic mesh in the theory of computational fluid dynamics(CFD) to realize the periodic variation of air suction, compression and discharge of screw compressor, and simulate the characteristics of internal flow field of the initial design line and the improved line by Fluent, comparative analysis the results find that it successfully demonstrated the correctness of the improved. Finally, the experiment scheme which is under the guidance of theoretical model was designed to test the pressure changes in the work process of screw compressor, which lays the foundation for further research. |
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