Peculiarities of modeling the work process in a low-pressure compressor of a gas turbine plant

The problem of weight decrease is crucial for modern gas turbine engines. Application of supersonic and transonic compressors is one of the ways of solving this problem. This allows reaching a higher pressure ratio at each stage than while using subsonic compressors and thus reducing the number of stages required to produce the desired value of pressure ratio. In compressors of this kind the flow is slowed down due to a system of shockwaves in the supersonic part and due to the flow deflection in the diffuser channels formed by the rotor blades and guide vanes in the subsonic part. The design of new compressors and modernization of old ones is inextricably connected with the usage of computational fluid dynamics methods at the present stage of engine construction development. The necessity of simulating a shockwave system imposes high demands on the construction of a computational mesh. In particular, the choice of the method of parameter passing between the domains of rotating blades and those of fixed guide vanes is an urgent task. It is shown in the paper that the use of different methods of averaging and parameter passing between domains can make a significant difference in compressor design characteristics (for example, a three-stage low-pressure compressor). Three methods of passing parameters between the domains that are used in the software package NUMECA/Fine Turbo are analyzed. The calculated compressor characteristics are compared with the experimental data at different rotation frequencies
of the rotor. The data obtained show the adequacy of the numerical model of the work process in the compressor under investigation. Typically, air bleeding for various needs takes place in compressors. Compressor performance changes when the air enters it, which should be considered in the calculations. It is shown in the example of the compressor tested that the inclusion of air bleeding results in quantitative and qualitative changes in the compressor performance. Among other things, parameters like pressure ratio and dynamic stability margin are changed, which may lead to inconsistent operation of the compressor as part of the engine. Thus, a conclusion about the necessity of taking into account the simulation of air bleeding in the calculation of supersonic compressors is made. The results obtained make it possible to expand the understanding of the working process of supersonic and transonic compressors and can be used later in the creation of numerical computational models of compressors of this type.