Experimental Studies of The Multi-cylinders Compound Profile Meshing Pair

In order to improve the wear resistance of the meshing pair in Single Screw Compressor, our team developed the multi-cylinders compound profile which could be used in the meshing pair instead of the traditional profile. In this paper, the reliability and utility of the new profile was verified by an experiment. In this experiment, a designed multi-cylinders compound profile meshing pair was applied in an oil-flooded single screw air compressor as the experimental prototype, then the prototype ran 2000 hours continuously in the experimental platform. and the displacement was detected with changing discharge pressure and rotating speed. It is shown that the prototype has a steady displacement, and the energy efficiency grade is very close to the best grade. The displacement is slightly reduced with the discharge pressure arising, but the reduction is far less than the original single line profile meshing pair machine. These prove that the new pair has good sealing performance. A comparative observation on the star wheel profile is conducted at the end of test, and the results demonstrate that the nodular cast iron star wheel new designed has high wear resistant property and good hydrodynamic lubrication characteristic. Thus, the nodular cast iron can be used to make star wheel to reduce the cost of the single screw instead of the expensive PEEK material

Research on Injected Effect and Heat-transfer Characteristics of Narrow-Slit Injection Orifice Used for the Screw Compressor

A narrow-slit injection orifice which is used for the screw compressor injection is described in this paper. Different from the traditional injection orifice, the orifice is slit shaped but not circular. Liquid which is injected by the narrow-slit injection orifice appears as a curtain shape so that the heat transfer area is increased. The cooling effect is enhanced and then the efficiency of the compressor is improved. The injected velocity of the orifice is simulated through the CFD software, and then the experiments are carried out. The study verified the accuracy of the simulation results. It will provide a theoretical foundation for the design of the narrow-slit injection orifice used for the screw compressor

Numerical Calculation and Analysis of Lubricating Water Film Cavitation of A Water Flooded Air Single Screw Compressor

Reynolds equations and one-phase model with N-S (Navier Stocks) equations are widely used to calculate pressure distribution in the liquid film. In most cases, negative pressure exits in the obtained results. In a water-flooded single screw compressor, it is necessary to investigate the pressure of water film along the whole tooth flank. A negative pressure may not be right, because that when the pressure is lower than the saturated vapor pressure, cavitation occurs. In this paper, we investigated the pressure distribution of the water film with cavitation model. Results were compared to the pressure distribution obtained by one-phase model using N-S equations. Results show that difference of pressure distribution obtained by the two models is very similar for the positive pressure distribution. For the negative pressure distribution, the saturated vapor pressure could be applied to replace the results obtained by one-phase model with very small errors. Therefore, one-phase model will be effective to simulate pressure distribution along the tooth flank by using the vapor pressure to replace the negative pressure

A New Design of the Tooth Profile for Single Screw Compressors

The wear of star wheel teeth is an importance issue in the single screw compressor. In order to enhance the wearresistance of star wheel teeth, some new profiles of the meshing pair were proposed to replace the currently used straight line envelope profile, such as single column envelope, multi-straight line (or multi-column) envelope. In this paper, a curved surface of the tooth flank is suggested. The groove flank is the envelope surface corresponding to the curved surface of the tooth flank. Section profile of the new tooth flank is a curved line, which could be elliptical, hyperbolic or involute. During the tooth meshing with the groove, the contact line between the tooth flank and the groove flank could move back and forth in the whole area of the tooth flank. This design is expected to improve the lubricating between the tooth flank and the groove flank, and to prolong the service life of the single screw compressor. Geometric and kinematic investigation of the star wheel and the screw rotor is established. And a new designed tooth flank of the meshing pair is introduced in this paper. Numerical control high-velocity cutting technology is suggested to fabricate the new star-wheel and the screw rotor