# Calculation Methods

Flow calculations were carried out on a design operation mode of the com­pressor for 2D-ft>w in system of cascades IGV-R-S on mean radius. From the measured radial distributions of stagnation pressures and temperatures on a path of the compressor, given on Fig.2, it is visible that fbw radial distortion is not great, and flow on the mean section on blade height is representative enough for the characteristic of flow in all compressor.

In the theory of potential-vortical interaction of cascades it is supposed that vortical wakes behind cascades in relative movement are given as universal velocity distribution in automodel area. In details specified theory is described in works [10,11] and used in [9].

At numerical fbw simulation averaged on Reynolds Navier-Stokes equa­tions were used, closed by two-parametrical (q, ш) model of turbulence. Fea­tures of the calculating scheme and construction of the grids are described in [13]. In the given work conditions of periodicity were imposed on the bottom and top borders of the calculating area, containing accordingly 18, 19, 18 air­foils in the IGV, R, S cascades at full simulation of conditions of experiment or 1, 1, 1 airfoils at the simplified flow simulation. In the latter case the gen­eral number of grid units has made 12700 at the minimal size of a cell at an airfoil, equal to 1,5 x 10-3mm. The step of integration on time was equaled T/3800, where period T = hR/u, hR is the R cascade pitch. Calculations were executed by V. G. Krupa.

The basic advantage of numerical simulation in comparison with the model of potential-vortical interaction consists in an opportunity of a direct estima­tion of influence of row unsteady interaction on time-averaged gasdynamical characteristics. From comparison of experimental and calculated circumferen­tial distributions of time-averaged stagnation pressures at the compressor exit for an optimum point (Uup = 125m/s, ф = 0, 5) on Fig.3 it is visible, that the calculated data are close to experimental.

It is necessary to note, that attempts of the simplified calculations by re­placement of the real relation of numbers of blades in the rows 183 19, 18 on simplified 1 1 1 resulted in essential deviations of calculated values from ex­perimental. Therefore all calculations, for which comparisons with experiment are presented, were received for real relation of numbers of blades.