Investigation of static wings interacting with vertical gusts of indefinite length at low Reynolds numbers

A novel gust generator was developed to study the interaction of wings with vertical gusts of controllable interaction time with magnitudes up to 30% of the freestream velocity at low Reynolds numbers. This work focuses on the collection of force and flow field data for three airfoils entering vertical gusts. Full-span NACA 0012, Eppler 387, and SD 5060 airfoils were tested with gusts of 20 and 30% of the freestream velocity at a Reynolds number of 12 x 10(3) and 20% of the freestream at a Reynolds number of 54.4 x 10(3). The lift generated during the gust interactions showed rapid increases in lift, often with a short-lived overshoot above the steady-state lift at the lower Reynolds number. Accompanying flow field data showed that the overshoot in lift was caused by a reattachment of the flow at the trailing edge of the symmetric NACA 0012, which was observed as a deflection of the streamlines in the freestream flow direction for the cambered airfoils. A new model was created to predict the lift during the interaction, which uses the static lift curve to predict the lift at a given effective flow angle, with corrections to account for the rate of change of the flow angle and camber of the airfoil. This model was able to more accurately predict the lift during gust interactions than the currently used modified Goman-Khrabrov model, while remaining a simple model to implement.

Automated summary

A novel gust generator was developed to study the interaction of wings with vertical gusts, and force and flow field data for three airfoils were collected under different gust magnitudes, revealing that a new model can more accurately predict lift during gust interactions.