AXIAL FLOW MULTISTAGE COMPRESSOR SURGE LINE DETERMINATION IN PERFORMING CALCULATION STUDIES

Abstract

The implementation of the high requirements for modern gas turbine engines depends on the perfection of their components. The reliability of the engine operation is largely determined by the compressor gas-dynamic stability margin. In this paper, a review and analysis of some of the most common approaches to determining the boundary of the compressor gas-dynamic stability region calculation are performed. Based on the analysis, it is shown that the diffuser factor and the equivalent diffuser coefficient are the most suitable for the practice of computational studies at the stage of designing and adjusting the compressor. However, different literary sources present different ranges of the limiting values of these criteria, corresponding to the boundary of gas-dynamic stability, which, in turn, can significantly affect the compressor stability margin. In this regard, it becomes necessary to determine the limiting values of the diffusivity criteria, which can be used both in the design of a compressor and in the construction of a model of a gas turbine engine using the proprietary description of blade machines. To analyze these criteria, we calculated a two-dimensional flow in an axial multistage compressor of a modern by-pass engine using the AxSym software package developed at the Department of Theory of Aircraft Engines of the National Aerospace University "KhAI". A comparison of the calculated data with the results of a physical experiment is carried out. The features of the change in the diffuser factor and the equivalent diffusion ratio depending on the compressor operating mode are established. Dependences which allow approximating the values of these criteria for different rotational speeds are proposed. Recommendations which specify the limiting values of the diffuser factor and the equivalent diffusion ratio for various compressor operating modes are presented.

Keywords

• осевой многоступенчатый компрессор
• граница области газодинамической устойчивости
• фактор диффузорности
• эквивалентный коэффициент диффузорности