PATTERNS OF GAS FLOW IN A HIGH-PRESSURE CENTRIFUGAL COMPRESSOR

Abstract

The development of three-dimensional modeling and analysis of the flow based on the solution of Reynolds-averaged Navier–Stokes equations allows to better determine the characteristics and flow parameters, but requires significantly more time spent on simulation and proof or verification of mathematical models in order to obtain minimal calculation errors. The aim of the work is to determine gas flow patterns in a high-pressure centrifugal compressor based on numerical methods for calculating the flow and to compare the integral characteristics with experimental data. The adequacy of the mathematical model with a displacement of the mass flow rate by 0.3 kg/s was confirmed. Nevertheless, the maximum mismatch of the determination of the total pressure ratio is equal to 8% in the zone of optimal values with flow displacement. The maximum error of determining efficiency is 9%. In the zone of optimal values, if the flow rate characteristic is shifted, the error of efficiency calculating does not exceed 2%. The pressure distribution along the impeller blades and the diffuser blades showed ways to optimize the blade shape to increase the compressor efficiency: there is an intersection of the lines for the optimal mode of the rotor blade; the splitter blade works in normal mode, but the distribution can be improved by changing the blade shape in the initial section; the intersection of the pressure lines for the optimal mode indicates the insufficient quality of the diffuser, which can be improved by changing the shape of the blade. For a more qualitative mathematical description of the flow patterns in the compressor, it is advisable to use the SST turbulence model, with a larger number of elements. The compressor characteristics were obtained numerically and the integral parameters of operation were determined. Keywords: high-pressure centrifugal compressor, numerical simulation, mathematical modeling, performances, adequacy