Design and Numerical Simulation of Rotor Profile of Prism Compressor
The design and numerical simulation of the rotor profile of the wide-angle rotor compressor was carried out by Zhang Zhaohe (Harbin Institute of Technology (Weihai, Shandong Weihai 264209) design or selection method. For the design of the prismatic compressor test prototype, CFD analysis was adopted. The software performs dynamic numerical simulation. The simulation results show that the compressor not only has excellent internal compression process, but also can achieve very high compression pressure. 1 Overview of the prismatic compressor as a novel rotary volumetric compressor with independent intellectual property rights (invention patent number: ZL200610042114.8), compared with the current screw compressor with market advantages, it has simple rotor processing and less leakage passage. (No leakage triangle, flexible design of intake and exhaust ports, low bearing selection requirements, low operating speed, low manufacturing cost, high working efficiency, etc.) The prismatic compressor has a wide range of applications, and it is basically applicable to the case of a screw compressor. The application of the prismatic compressor technology on the basis of the existing industrial technology can maximize the inheritance of the existing screw compressor technology, such as the selection and design of the rotor profile of the prismatic compressor, as well as the use of the prismatic compressor. The selection and design of bearings, shaft seals, synchronous gears, and machine structures can make full use of the technical achievements of existing screw compressors. This is the promotion of prismatic compressors and the working principle of the prismatic compressors. A bilateral symmetrical arc-shaped rotor profile was designed, and the main components of the test prototype were designed. Then the CFD-based numerical simulation was carried out on the compression process. 2 Rotor profile design In the prismatic compressor, the profile design of the rotor is a key task in the design of the entire prismatic compressor. According to the law of meshing, the ratio of the number of ridge type faces on the male and female rotors of the prismatic compressor to the number of grooves of the concave type is equal to the ratio of the diameter or radius of the pitch circle of the anode and the cathode, and the anode and the cathode are usually preferred. The ratio of the number of rib type faces to the number of groove type faces is 2/2, 2/3, 3/3, 3/4, etc., so that the highest possible pressure ratio can be obtained. Similar to the screw compressor, the rotor profile of the prismatic compressor has both a symmetrical line and an asymmetrical line, and a single-sided line and a double-sided type. For the screw compressor, various asymmetrical lines are designed in order to minimize the influence of the leakage triangle on the leakage and power consumption of the whole machine, but for the prismatic compressor, since it does not exist in the structure The triangle is leaked, so a simple bilateral symmetrical line can be used as much as possible, which avoids the sharp point and stress concentration on the rotor type line, and ensures the design, manufacture and debugging of the prismatic compressor. In this paper, the bilateral symmetric circular arc line is taken as an example to illustrate the design process of the rotor profile of the prismatic compressor of the rotor combination scheme with the ratio of the number of profiles being 2/3. The two-symmetric circular arc line of the female rotor with a groove type of 3 is shown, and the radius of the pitch circle is Ra. The bilaterally symmetric circular arc of the male rotor with the number of ridges is 2, and the pitch circle is shown. The radius is Rit, and the number of synchronous gear teeth connected to the positive and negative rotor shafts is Zi and Z2 respectively. The gear ratio of the gears on the middle and the yin and yang rotors and their corresponding relationships are shown in Table 1. AB, EF, HI, and LM are the center of the arc of the respective rotor pitch and the radius of the arc segment, the radius of the arc is different from the design of the screw compressor, regardless of its leakage triangle influences. The CD segment and the K segment are circular arc segments of radius R, wherein the top of the K arc segment on the male rotor is completed by the outer circle having a diameter of 2Rit+2R-A or 2Ra+2r. The cutting effect, the advantage of this is: (1 can form a face seal between the male rotor and the inner cavity wall; Q compression can end up to obtain a smaller clearance volume; (3 through the size adjustment can make the body of the female and male rotor The inner diameters of the inner chambers are equal, so that the stress distribution and heat dissipation of the housing are more uniform, and the molding and processing of the housing are also facilitated. Table 1 yin and yang rotor bilateral symmetrical circular arc line composition tooth curve Yin rotor Yang Rotor arc Cycloidal point Cycloid arc point Cycloid point arc The above arc segment equation is obviously easier to determine. The BC, DE, I, and KL segments are pendulum segments. The derivation results of the cycloid equation are the values ​​of the center å± and the range of values ​​still determined by the geometric relationship in the graph according to the coordinate transformation relationship and envelope conditions. On the basis of the determination of the rotor profile, the rotor profile is stretched in the direction of the rotor axis to form a grooved or ribbed profile that is parallel to the axial direction of the female and male rotors, thereby completing the male and female rotors. The shape of the main part is as shown. The essential difference between the rotor in the prismatic compressor and the rotor in the screw compressor can be seen from the figure. At the same time, based on the determination of the rotor profile, according to the equation of the tooth curve of the yin and yang rotor, combined with the actual structural dimensions of the rotor and the ~-shaped cylinder and the starting position of the exhaust orifice, the teeth of the yin and yang rotor can be obtained by analytical method. The area between the area and the end of the compression, such as AM, 42 and 43. According to the effective working length L of the yin and yang rotor, the inter-tooth volume V actually involved in the compression stroke can be obtained, that is, if the compressed gas is ideal For gas, the internal pressure ratio of the prism compressor can be approximated, that is, the ratio in the parentheses is the internal volume ratio of the prism compressor, and m is the multi-process index, which can be selected by referring to the empirical data of the screw compressor. The journal portion outside the rotor body is designed in accordance with the design method of the ordinary shaft. Similar to the rotor design principle of the screw compressor, the rotor of the prismatic compressor is also divided into an integral type and a combined type. It may also adopt an internal cooling structure or a sealing tooth or a sealing rib. In addition, since the two rotors of the prismatic compressor are rotated by the synchronous gears, the two rotors are actually not in contact, so that the selection of the rotor of the prismatic compressor can be made wider than that of the rotor of the oil-injected screw compressor. In this paper, the rotor material of the prototype is made of ordinary medium carbon steel. 3 Other main components design and selection 3.1 The body is one of the main components of the prismatic compressor. It is the carrier for the compressor rotor, bearing, shaft seal, synchronous gear and other components. Similar to the screw compressor, it is also composed of the cylinder part of the middle part and the end cover of both ends. The side end cover can be integrally molded with the cylinder body according to the actual situation, or can be manufactured separately. Since the inlet and exhaust ports of the prism compressor are more flexible than the screw compressor, the intake and exhaust ports can be designed to be either radial suction or exhaust, or can be designed for axial suction and exhaust. In addition, the cylinder of the prismatic compressor can also be designed as a single-wall structure or a double-wall structure as needed. In addition, the body material of the prismatic compressor can also be selected from different materials such as ordinary gray cast iron, ductile iron, cast steel, alloy steel or stainless steel. The test prototype involved in this paper adopts a structural form in which one end cover and the cylinder are integrally cast, and the inlet and exhaust ports are designed as a radial suction and exhaust structure, the cylinder body is a single-layer wall structure, and the material is made of ductile iron. 3.2 bearing bearing is also one of the key components of the prismatic compressor. Similar to the screw compressor, the bearing used in the prismatic compressor is also divided into two types: rolling bearing and sliding bearing. In non-large-scale prismatic compressor, rolling bearing is generally used. . However, since the male and female rotor profiles of the prismatic compressor are straight flank surfaces, no axial force is generated during the rotation, so that only the diameter of the spur gear and the axial suction and exhaust pressure can be selected. Xiangli radial bearing reduces the number of bearings compared to screw compressors; and because the speed of the prism compressor is lower, it can be replaced with domestic bearings instead of imported bearings. Bearings replace high-precision bearings. The test prototype of this paper only uses 4 domestically produced P5 grade angular contact ball bearings. 3.3 The principle of selecting the shaft seal of the shaft seal prism compressor is similar to that of the screw compressor. For oil-free prismatic compressors, graphite ring seals, labyrinth shaft seals or mechanical shaft seals are available; for oil jet prism compressors, a certain pressure can be applied between the rotor body section and the bearings The sealing oil is sealed. In the outer shaft section of the rotor, a simple lip seal can be used for sealing, or an oil-lubricated mechanical seal can be used. In addition, for the prismatic compressor, the shaft seal can be selected without distinguishing between the intake end and the exhaust end. The test prototype of this paper designs a seal oil seal between the rotor body section and the bearing, and a lip seal seal is used in the outer shaft section of the rotor. 3.4 Synchronous gears Because the number of meshing teeth on the rotor of the prismatic compressor is small, both the oil jet prism compressor and the oilless prism compressor must realize the synchronous rotation of the rotor group by the synchronous gear, so the synchronous gear is also a prism. The main components of the rod compressor. Similar to other compression machines with synchronous gear mechanisms, in order to ensure the meshing accuracy of the rotor, the accuracy level of the synchronous gear of the prismatic compressor also has higher requirements, and must be above 6 accuracy. In addition, in order to prevent the axial displacement of the gear, the correct meshing relationship of the rotor is destroyed, and at the same time, in order to ensure the installation and adjustment during assembly, the synchronous gear is more reliable with a spur gear. The test prototype of this paper is designed with a pair of spur gears, in which the synchronizing gear connected to the female rotor is designed as an adjustable structure. 4 Numerical Simulation of Compression Process In order to investigate whether the prismatic compressor test prototype completed according to the above design idea can realize the internal compression process, the dynamic simulation of the compression process is carried out by using the CFD analysis software using the dynamic mesh technology for the simplified model of the test prototype. The dynamic numerical simulation results of the pressure distribution in the compression chamber of the test prototype at different rotational speeds are shown, where Q and the pressure distribution in the compression chamber are 1200r/min and 3000r/min respectively, and the pressure unit is Pa. See from the figure The gas pressure in the inter-tooth volume involved in the compression process has reached a local instantaneous pressure of 2.81 MPa and 4.23 MPa respectively before the communication with the exhaust port at two rotational speeds, and the local instantaneous pressure also increases with the increase of the rotational speed. It has increased significantly. The above numerical simulation results on the one hand reflect that the prismatic compressor can achieve a strong internal compression process, and on the other hand, it reflects that the increase of the rotational speed can improve the speed sealing effect, which is consistent with the actual situation of most gap seal type compression equipment. . 5 Conclusion Taking the bilateral symmetrical arc rotor profile as an example, the design of the rotor profile of the prismatic compressor test prototype is completed, and the derivation results of the bilateral symmetric circular arc-shaped line segment line equation are given, and the prism compression is introduced. Design and selection methods for other major components of the machine test prototype. Using the CFD analysis software, the dynamic model of the compression process was carried out by using the dynamic grid technique for the simplified model of the test prototype. The results show that the local instantaneous pressure is obtained in the inter-tooth volume involved in the compression process, confirming the prismatic compressor. A strong internal compression process can be achieved. Hand Held Super Scanner, due to some supplier R&D some model that hot sold, and widely welcomed. Also price very acceptable. Hand-Held Metal Detector protect people's life from being hurt and property being damaged by terrorism. Chinese Held held Metal Detector is cheap but also good in use. And also offer 1 year warranty, it worth your choice! Hand Held Super Scanner Hand Held Super Scanner,Hand-Held Super Scanner,Hand Held Metal Detector Super Scanner,Security Super Scanner Shenzhen Mama Security Technology Co., Ltd. , https://www.mamasecurity.com