This research presents a hybrid approach to calculating wall interference corrections for solid wall wind tunnels. The proposed approach is based on nonlinear least-squares optimisation, using static pressure measurements at the tunnel walls to implement analytical solutions using numerical methods. The method is able to determine the wall interference by using a combination of fundamental flow elements that are able to vary in both strength and position.

The method is validated against analytical methods, CFD, and experiment with comparisons drawn to the wall measurement-based 2V method implemented at the QinetiQ 5m Wind Tunnel. Experimentally validated CFD has been evaluated for a range of bodies, including a 2D cylinder, 2D NACA 0015 with deployed spoilers, a delta wing with three degrees-of-freedom, and a powered electric ducted fan, with verifiable free-air solutions to determine the effectiveness of the corrections proposed.

The results demonstrate that the NLSQ approach is capable of achieving drag corrections superior to the well-established two-variable method, while being able to achieve consistent lift and pitching moment corrections. The NLSQ method has been implemented using a vortex panel approach, and is able to obtain a correction in the order of one minute using a high degree-of-freedom representation, while a coarse representation can be calculated within seconds.

Wall crossflow was highlighted as a key advantage of using this approach, as it could explicitly correct for wall velocities. However, the accuracy of these measurements depends on the resolution of the wall tapping locations, which is typically lower in the wall spanwise direction. Recommendations for future work involve further analysis into resolving wall crossflow. Other recommendations include code optimisation and viscous potential flow modelling.