Comparison of the Linear and Non-linear Unsteady Aerodynamic Forces on the Vibrating Blade Row

摘要

In the present paper, the CFD of the linear and non-linear unsteady aerodynamic forces on the vibrating blade row are discussed and the results are compared. In the linear unsteady calculation, the precise formulation is attempted in the frequency domain and the second-order terms are neglected. In the non-linear unsteady calculation, on the other hand, in order to execute the calculation in one blade passage when there is a finite interblade phase angle, the reference papers in the past usually used the Fourier series expansion to keep track of the history at the interblade boundary. In the present paper, however, it is adopted the novel idea of keeping the time history of the physical properties on the grids point adjacent to the interblade boundary in one period. During the time-marching iteration in the vibration period, the physical properties at the interblade boundary are updated and made use of. The update and usage is executed to the displaced storage location which corresponds to the interblade phase angle. The numerical comparison between the linear and nonlinear unsteady pressures on the STCF11 (Standard Configuration 11) and the flat plate in a supersonic relative flow is made. Since the linear and non-linear formulations are consistent and their calculation codes are based on the same URANS code of UPACS (Unified Platform for Aerospace Computational Simulation) which is developed by JAXA (The Japan Aerospace Exploration Agency), Japan, the difference between the linear and non-linear calculations is confirmed to be not large when compared with the reference papers.