Gazdynamic characteristics of the centrifugal compressor calculation

Abstract

Gas-dynamic characteristics of the compressor make it possible to evaluate its energy and economic properties, to predict the values of capacity, the generated gas pressure and the power consumption during the compressor operation. For more in-depth consideration of the compressor, it is desirable to have the characteristics of its individual stages. The element-by-element analysis of the characteristics of each stage makes it possible to improve the coordination of the operation of the individual elements with each other and thereby improve the gas-dynamic characteristics of the compressor. The loss factor and the static pressure recovery factor can be used as the values characterizing the properties of the individual elements of the stage. Coefficients are suitable for evaluating the energy properties of any element of the stage. To assess the effect of the element in question on the economy of the stage, it is necessary to establish what proportion of the work required for compression is the "loss" of energy in a given element, i.e. find the reduction in efficiency stage due to dissipation of energy into heat in this element. Calculation of performance of the centrifugal compressor is performed from the inlet to the outlet using the equations of state, of process, of continuity and conservation of energy. The initial data are geometric parameters of the compressor, the composition and the initial parameters of compressed gas, the rotational speed of the rotor. The basis of the elementwise calculation of gas-dynamic characteristics is the gas-dynamic characteristics of the stage elements. The calculation can be performed using the characteristics of the stage elements taken from the own bank of experimental data or using the generalized characteristics of the stage elements. To obtain generalized characteristics of the impeller, blade and no-blade diffusers, reverse guide vanes, experimental data were used, published in the works of Galerkin, Den, Rees, Seleznev and others, as well as experimental data obtained by the author. The generalized characteristics are obtained in the form of analytical dependences of the loss coefficients on the angles of attack or flow angles by approximation of experimental data. These dependences were used to analyze the gas-dynamic characteristics of a centrifugal compressor, which made it possible to develop recommendations for their improvement.

Keywords

• Centrifugal Compressor
• Stage
• Elementwise Analysis
• Performance
• Impeller
• Diffuser