Experimental verification of PIV-based measurement for reconstructing thrust performance of supersonic nozzles

The conventional force measurement system using the balance has the problem of only being able to measure the overall load but unable to decouple the contribution of individual components, which limits the exploration of the flow mechanism behind aerodynamic load. With the development of Particle Image Velocimetry (PIV) technology，the PIV-based aerodynamic load measurement technology was developed, which can indirectly measure aerodynamic load by reconstructing multiple physical fields such as pressure and density. However, the performances of conventional pressure reconstruction methods were severely deteriorated when applied to supersonic flow fields. This drawback limits the application of reconstruction measurement methods in supersonic nozzles. To resolve this issue, a method for reconstructing the supersonic pressure field based on the Flux Vector Splitting (FVS) technique was proposed, and a thrust performance measurement scheme for supersonic nozzles based on PIV was established. PIV experiments on the Single Expansion Ramp Nozzle (SERN) were conducted using the direct-connect wind tunnel. Multiple physical fields and aerodynamic performance parameters such as flow rate, thrust, and lift were reconstructed under typical operating conditions. The evaluation results show that the data reconstructed by the FVS method possessed higher accuracy and better self-consistency, satisfying the laws of mass and momentum conservation. The relative errors of thrust and lift under overexpansion conditions were only −1.70% and 0.60%, respectively. The local errors of wall pressure after shock wave were lower than 3%. The performance of the proposed method is shown to be better than that of the conventional Poisson method and Spatial Integration (SI) method. Therefore, the experimental results verify the feasibility and high accuracy of the PIV-based thrust performance reconstruction measurement method when applied in supersonic nozzles, which can provide effective data supplementation to force measurement with the balance.