Physics-Informed Filtered Rayleigh Scattering as a Ground Force Decomposition Technique

Abstract A physics-informed filtered Rayleigh scattering model is applied to a supersonic jet flow with a core flow at ambient temperature and a heated bypass flow. This model serves as a surrogate for larger-scale flows like turbofan engine exhaust. The limited spatial resolution allows for a high uncertainty test case for the force decomposition methodology. The method is evaluated using a CFD simulation and measured FRS data. The simulated jet flow provides a noise-free baseline, while the experimentally measured jet flow demonstrates the reduction in uncertainty even with measurement noise. The net force from all results compares within ±10 N (≈ 3% of net force value). The net force is decomposed into core and bypass contributions using the maximum of the gradient of axial velocity, static temperature, and static density. All three gradient approaches compare within ±8 N (≈ 2% of net force value), and the bypass force contribution uncertainty can be reduced by a factor of two relative to previous non-intrusive force decomposition techniques. This demonstrates an advancement of the filtered Rayleigh scattering force decomposition approach through its increased capacity to handle noisy data, enabling its deployment in ground test and on-wing applications.