No abstract

The article deals with the issues of the 3D impellers strength analysis for the different centrifugal compressors. Two air compressors are considered, the first for General industrial use, the second for turbocharging the internal combustion engine. The third compressor is designed for the turboexpander unit that operating at high pressure medium. The materials of the impellers were steel, titanium and aluminum alloys. The expediency of using the Fluid-Structure Interaction approach for the strength analysis is considered for these compressors. With the FSI approach, a coupled CFD-FEA solution is performed. Gas-dynamic forces from the medium pressure are taken into account in the impeller strength or vibration analysis. The Ansys package is selected as the program for analysis. CFD models are built and configured in the Ansys CFX. The FEA solution carried out in the Ansys Static structural. The results of strength analysis are compared with and without pressure forces for all impellers. As a result, there were no significant differences in the two solutions for the air compressors. However, for high-pressure compressors, the results of the coupled solution showed the need to take into account the CFD solution. Based on the obtained data, a graph of the reliability coefficient dependence on the increase in the suction pressure in the range from 1 to 100 bar is plotted.

A new mathematical model has been developed to determine the coefficient of internal and theoretical head in the variant design of the low-flow rate centrifugal compressors impellers. A parametric study of the flow part of the impeller is carried out. In total 1620 impellers are numericaly simulated. As a result, a numerical database of gas dynamic and geometric parameters was developed. Due to an a priori analysis, the relations of parameters with the geometric shape of the flow part are determined. The mathematical model is developed using gas-dynamic parameters and relations determined from numerical database. Using centrifugal compressor stage digital twins, a generalizing relationship has been developed to determine the complex of friction and leakage losses.The reliability of the math model is validated by the comparison with experimental data and the results of numerical experiment in digital twins, which are not involved in the model. The application of the head math model is determined in the range of the conditional flow coefficient 0.006<Φd<0.02 and the theoretical head coefficient 0.60 <ψt<0.72.

The article deals with the choice of key geometric parameters and the range of their variation in solving the optimization problem of centrifugal compressor impellers using computational fluid dynamics. The study was carried out using Numeca Fine / Turbo package. The influence of more than 10 geometric parameters on the efficiency and the head of the impeller was considered. The influence degree evaluation of investigated optimization parameters was provide by changing the parameters value in a preset range and analyzing their impact on the efficiency and head of the impeller. As a result, the main geometric parameters of optimization, which should be considered first, were identified. Other parameters may not be considered within the optimization problem, and can be assigned to the standard values. In addition, recommendations on optimal ranges of parameter values were given.

The goal of this work is to develop recommendations for the calculating problem formulation of the medium flow centrifugal compressor characteristics by computational fluid dynamics methods with the assessment of the computing resources necessary costs. Calculations are made on supercomputers of SPbPU “Polytechnic” and “DeltaCluster”. The object of the research is the centrifugal compressor stage for which the flow investigation has been held in the whole passage. The calculations result comparison with the practical experiment data for the whole working characteristics are shown in this work. The leakage in the lap seals and between the disks gaps investigation work has been made. The calculation of the whole 2π flat pattern has been made and also the influence on the calculation results of the between mesh interfaces has been analyzed.