A Study Of New Type Configuration Of Blade Cascade In Axial Compressors

The numerical investigation of steady and unsteady flow in axial compressor with equally spaced blades and unevenly-spaced blades was carried out in this paper. A computer code was developed. Two-dimensional unsteady Navier-Stokes equations were solved with high-resolution scheme. The steady flow results were obtained by LU-SGS implicit method. Dual time-stepping approach in conjunction with LU-SGS implicit method was used to solve the unsteady flow fields.Firstly, the numerical simulations of steady flow and unsteady flow introduced by rotor-stator interaction in a single-stage axial compressor were made. The results of design and off-design performances at 100%, 90% and 80% design rotating speed are presented. The numerical analyses show the steady flow solutions will give lower efficiency prediction than that of the unsteady flow. However, the total-to-total pressure ratio results of the unsteady flow calculation are lower at large incidence angle. And the stall margin can be determined by the unsteady computed results. The operating state is stable if the unsteady blade surface pressures vary periodically with time, while it is unstable when the variations are not periodic.The effects of solidity of rotor-stator cascades on compressors performance was simulated with steady and unsteady flow calculations. The comparison of results shows that the solidity of rotor blade cascade plays an important part in stage total to total pressure ratio. With the increase of rotor blade cascade solidity, the efficiency is lower at design operating point but higher at large incidence angle. By the comparison with unsteady flow results, the steady flow solutions for efficiency show a differentbehavior. The unsteady flow calculation can predict the effect of rotor-stator interaction more accurately.The main effort is focused on the flow field in axial compressor with uneven blade spacing. The numerical simulations of unsteady flow were carried out for rotor-stator and IGV-rotor-stator configurations. The effects of different uneven blade spacing configurations on compressor performance and rotor blade aerodynamic force are presented. For the rotor-stator configuration, the unsteady flow analyses of a compressor stage with uneven space rotor blades and uneven space stator blades were made. The results show almost no effects on efficiency and total pressure ratio with uneven space stator blades. But the total pressure ratio falls near stall points and unsteady blade force increases using uneven space rotor blades. For a compressor stage with IGV, the study was made for different configurations with even space rotor blades and uneven space IGV and stator blades. The calculations predict no influence on efficiency and total pressure ratio. The unsteady force over the rotor blade decreases for one of these configurations. The results show the benefit to the life of compressor rotor blade for the adoption of uneven space stator blade.