Linkages of Stages in Vortex Multistage Compressor

Abstract

Extent of increasing pressure in a vortex stage is limited to value of gas temperature on forcing. Because of the rather low efficiency (E) values of a vortex stage, gas temperature in the course of compression in a stage significantly increases. Therefore, to receive a higher extent of compression in the compressor the multistage scheme with intermediate cooling between the stages is applied. However, linkage of stages in the multistage scheme requires taking into consideration a need to match all stages, and first of all, by a value of the coefficient of the discharge defining a zone of the maximum efficiency. It is especially important for last stages in which as a result of compression and intermediate cooling the volume discharge significantly decreases.

The article considers various options of linkages of stages, namely: with identical rotor frequency; with identical diameters of driving wheels on stages, but with different frequencies of rotation. The stages were assumed to run at a constant value of the coefficient of discharge which size was defined when calculating the first stage. Except the above-named parameters of stages, the paper also considers a possible pattern of loading distribution by stages either a uniform distribution, or that of with increasing load at the first or last stages.

All options of linkages are illustrated using the calculation of the three-stage vortex compressor with intermediate cooling as an example. The calculation uses characteristics of a vortex stage in dimensionless parameters. Calculation results allowed us to analyze changes of key parameters of vortex stages and choose the most rational option of the three-stage compressor linkage.

It is shown that matching of stages can be achieved, in particular, through the use of driving wheels with the identical outer diameter and geometry of flowing part, but with various rotation frequencies of stages. For this purpose the paper offers to make the vortex compressor according to the known scheme of the cross-compound integrally geared compressor in which with raising the number of stage the rotor frequency decreases.