Research on Performance of Variable-Lead Rotor Twin Screw Compressor

Twin-screw compressors are widely used in aerodynamics, refrigeration and other fields. The screw rotors are the core component of the screw compressor and affect the performance of the compressor. This paper focuses on variable-lead rotors. A thermal process simulation model considering leakage is established to calculate the efficiency of the compressor. Different lead change methods are compared by evaluating the contact line, exhaust port and simulation results. The results show that the compressor obtains better performance when the lead decreases rapidly on the discharge side. Furthermore, the effects of the wrap angle and internal volume ratio on variable-lead rotors are studied. The work provides a reference for the design of the screw compressor rotor.

PRINCIPLES OF FORMATION AND DESIGNING EQUIPMENT FOR FINISHING PARTS ON SCREW ROTOR BASIS

There are presented technologies and equipment based on screw rotors where technological and transportation operations are combined. The methods and ways for the speed performance comparative analysis of screw rotors are shown, for that there are carried out experimental investigations to determine a motion rate of parts with different weights from rotation frequency of screw rotors of 1-4 types. The results are accumulated in alignment charts which allowed creating a procedure for an engineering calculation of screw rotors. The original designs of such operation units have Russian priority and they are presented in fifty one patents for invention of the Russian Federation. In the paper there are offered methods and ways for the comparative analysis of screw rotor speed performance, the procedure for the engineering calculation of screw rotors. There is presented a machine for finishing parts with replaceable screw rotors of 1-4 types. The productivity and reliability increase of operation in such equipment is achieved at the expense of uninterrupted supply, dosage and reliable delivery of abrasive grains and parts into the operation unit made in the form of a screw rotor, worked parts separation from abrasive grains and working wastes, damage decrease of parts worked and their marketable appearance improvement, and also labor conditions improvement for the staff. There are shown inventions developed by the authors and for which they obtained patents of the RF and the information of which may be useful at the creation of equipment for OZO parts based on screw rotors.

Designing nano-aluminum laden fuel pump for aviation applications

In view of the fact that traditional liquid propellants cannot meet the design requirements of large-thrust flight vehicle, it has become a new trend to add nano-metal powder to liquid propellants to greatly increase density and specific impulse. In order to achieve the variable flow-rate and variable-proportion transportation of aviation fuel with nano-aluminum, a new type of solid-liquid mixing pumping system is designed, including powder conveying device, stirring device, pump and corresponding drive and transmission system. For the purpose of avoiding the frictional contact between the rotors, which will bring potential hazard to nano-aluminum powder, a non-contact twin-screw pump with synchronous gears is designed. Among them, based on the considerations of flow pulsation, volumetric efficiency and manufacturing difficulty, cycloid profile is adopted for screw rotors. After completing the functional design, geometric parameter design, structural design, 3D modeling, prototype manufacturing and preliminary performance estimation of the mixing pumping system, the performance of the screw feeder, agitator, screw pump was tested through experiments to meet the expected design requirements. The designed agitator can achieve sufficient mixing at 500 rpm in less than 10 s. Even though 50-micron clearances are designed with a relatively small rotor diameter, the volumetric efficiency of screw pump can reach above 50% when the discharge pressure is below 450 kPa and the flow rate is set as 10 L/min, the power of the screw pump is less than 700 W. This design facilitates the rapid real-time preparation of metallized propellants and provides a reference for further improving the design and control methods of nanoparticle two-phase flow pumping.

EQUIPMENT FOR GRINDING-FINISHING BASED ON SCREW ROTORS

The results of a long-term scientific work in the field of the creation of machines, plants, devices for machinery finishing for the creation of innovation equipment based on screw rotors are shown. There are presented standard structures of machines ensuring machining a wide range of parts of engineering enterprises. There are formulated basic recommendations for a choice of machining operation environment as such one can use abrasives and non-abrasives of different granulation. These recommendations take into account material, mass, rigidity of the parts worked and a grade of screw rotors. There is shown an example of calculation and an experience of designing a plant for parts continuous grinding-finishing on the basis of a screw rotor of the IIId grade. Working drawings and technologies for manufacturing operation units of these machines and plants are offered.

EQUIPMENT FOR GRINDING-FINISHING BASED ON SCREW ROTORS

The results of a long-term scientific work in the field of the creation of machines, plants, devices for machinery finishing for the creation of innovation equipment based on screw rotors are shown. There are presented standard structures of machines ensuring machining a wide range of parts of engineering enterprises. There are formulated basic recommendations for a choice of machining operation environment as such one can use abrasives and non-abrasives of different granulation. These recommendations take into account material, mass, rigidity of the parts worked and a grade of screw rotors. There is shown an example of calculation and an experience of designing a plant for parts continuous grinding-finishing on the basis of a screw rotor of the IIId grade. Working drawings and technologies for manufacturing operation units of these machines and plants are offered.