Effects of the Large Eddy Simulation Calculation Parameters on Prediction of Profile Loss in an Axial Cascade at Off-Design Incidence

Profile loss in axial compressor cascade, which is usually taken to be the loss generated in the blade boundary layers well away from the end walls, should be considered at the initial design process. An accurate prediction of profile loss under a wide operating range including off-design condition is necessary for designing a high-performance axial compressor. Generally, prediction of profile loss is calculated by mathematical correlation or Reynolds Averaged Navier Stokes(RANS) in the design process of the axial compressor. Since the profile loss originates by the turbulent boundary layer of the blade wall and large separation (for high incidence) in the turbulent flow field, high-accurate unsteady flow simulation is needed to predict profile loss accurately. Large Eddy Simulation (LES) has already been widely applied for unsteady flow simulations including axial compressor cascade simulation and showed its superiority in simulating turbulent flow field. However, there are several obstacles in the practical using of LES as a design tool. Calculation parameters such as the size of the calculation domain, time step size, boundary conditions, etc. affect calculation results for LES simulation, which incurs reliability issues. In this research, wall-resolved large eddy simulation has been used for profile loss calculation on the British C.4 linear cascade blade. Chord based Reynolds number is 157000, which is equal to reference experimental condition. For the design angle of the blade, results of profile loss prediction show good agreement with reference experimental data. However, for the off-design angle, large eddy simulation does not predict experimental data accurately, and this trend is common with other large eddy simulation researches. As it has been already known that calculation parameters for large eddy simulation affect its calculation results, especially on complex flow fields such as high incidence flow, this mismatch for off-design angle could be originated by calculation parameters. Therefore, in current research, the effect of calculation parameters for cascade large eddy simulation at the off-design incidence has been investigated.