Non-intrusive aerodynamic load reconstruction method for supersonic nozzles based on particle image velocimetry

Conventional balance force measurement systems may suffer from slow dynamic response and loss of high-frequency load signals due to the contact measurement characteristics. With the advancement of particle image velocimetry (PIV) technology, a PIV-based aerodynamic load measurement technique has been proposed, which indirectly measures aerodynamic loads by reconstructing multiple physical fields such as pressure and density. However, the performance of conventional pressure field reconstruction methods is severely reduced when applied to supersonic flow fields, which limits the extension of PIV-based aerodynamic load reconstruction method to supersonic nozzles. To address these challenges, this study proposes a multi-physics fields and aerodynamic load reconstruction measurement for supersonic nozzles based on the flow vector splitting (FVS) technique. Both simulations and experiments are conducted to validate the FVS method. The pressure fields of flows involving shock wave/boundary layer interactions and nozzle internal flows with strong shocks are reconstructed by simulation data. Furthermore, multi-physics fields and aerodynamic performance parameters of two typical supersonic nozzles are reconstructed using experimental data. Evaluation results show that the reconstructed data calculated based on the FVS method achieve higher accuracy and better self-consistency, satisfying conservation laws of mass and momentum. The relative errors of thrust and lift are smaller and the local errors in post-shock wall pressure remain below 3%. These results outperform the conventional Poisson method and spatial integration method. Therefore, the experimental results have verified the feasibility and high accuracy of the PIV-based aerodynamic load reconstruction methodology for supersonic nozzles, which can provide valuable complementary data to conventional balance force measurement technology.