The use of mathematical optimization means to increase the efficiency of a seven-stage axial flow compressor

The paper describes a method of computer-aided redesign of axial flow compressor blades. The method is based on the combined use of the NUMECA computational fluid dynamics software package and the IOSO program optimizer. The basic idea of the method is that, at each iteration, the optimizer generates a variety of parameters that determine the compressor’s geometry. Finite-element models of a compressor are created on its basis in the NUMECA AutoGrid program. The parameters of operation in one or more points on the characteristic of the compressor are calculated in the NUMECA Fine / Turbo program with their help. The calculation results are transferred to the optimizer, where the obtained values are compared with the specified limits. Then a new set of input data is formed. The cycle is repeated until the required criteria of the compressor operation are achieved. The developed method was tested on a seven-stage high-pressure compressor of the NK36-ST engine. The article describes the constructed numerical model and the results of the verification by comparing the calculated data with the experimental data. The model developed makes it possible to obtain results close to the experimental ones and does not require large computational resource. The optimization of the compressor was carried out in two versions using the developed model: 1) increasing the efficiency of the operation mode with the rotation frequency of the rotor of 100% of the maximum by changing the blade setting of the first three stages, 2) improving the efficiency of the two operation modes with the the rotation frequency of the rotor of 80 and 100% of the maximum due to changing the blade setting. It is shown that in the first case the compressor efficiency can be increased by 0.3%. In the second case, the efficiency can be increased by 1.2% at the rotation speed of 80% and 0.5% at the speed of 100% just by changing the blade setting.