Fluid-Structure Interaction of a Spring-Mounted Symmetrical Rigid Wing for Drag Reduction of Cars at Higher Wind Velocities

Abstract

This paper details an aeroelastic concept for an adaptive and passive wing, which is primarily aimed for use within automotive sector to reduce drag and fuel emissions. The work will also be of interest in the motorsport sector to improve performance and also some applications within aerospace and renewable energy sectors. The wind tunnel testing of a spring mounted symmetrical NACA 0012 wing in freestream is studied over 0° to 40° angles of incidence. General operation of the concept is verified at low angles in the prestall region with that of a theoretical estimation using finite and infinite wings. Three distinct regions are identified, pre-stall, near-stall and post-stall. The transient limitations associated in the near-stall region with variations in spring loading and flow velocities are discovered. It is identified as a periodic self-sustained oscillation with non-dimensional reduced frequencies in a range of 0.14 to 0.22. Furthermore, performance in the post-stall region along with pre-stall is reported and methods for the adjustment of the elastic element for a desired response are introduced. Evaluation is conducted with regard to an automotive application such as a rear wing on a high downforce race car. Typically a 25% increase in wind velocity in the pre-stall region results in a 3°-5° change in angle of incidence corresponding to a 25-40 % reduction of drag coefficient depending on spring stiffness. Reductions of 20° in angle of incidence with similar 25% increase in wind velocity are typically found in the post-stall region. Even larger reductions are found when transitioning through the stall region. This work provides a valuable insight for a novel concept, but we only recommend its use in the pre-stall region to achieve steady results. Use at higher angles is only recommended if transient effects are not important. Limitations to this proof of concept work are highlighted and future development work is suggested to achieve further increases in performance.

Fluid–Structure Interaction of Symmetrical and Cambered Spring-Mounted Wings Using Various Spring Preloads and Pivot Point Locations

“…A simpler form of these equations using the symmetrical NACA 0012 at low angles of incidence have been validated with experimental results [43]. The experiment confirmed the results of the change in angle with windspeed to be within theoretical infinite and finite wing for small angles.…”

“…The system is set up similar to the work of Poirel et al [42], except we omit the effect of heave in our approach. The proof of concept and validation of our system has been shown by Knight et al [43] for the symmetrical NACA 0012 mounted at 10% chord. The aim of the work reported here is to further analyse the fluid-structure interaction of the symmetrical NACA 0012 with various pivot point locations and to compare this with the cambered NACA 6412.…”

“…The present study builds upon an aeroelastic system, in which a ridged wing selfadjusts its angle of incidence to the airflow velocity using an elastic element. The system was also presented and verified at low angles in a previous study by Knight et al [43]. The general system uses a wing mounted upon a rod with only a rotational degree of freedom in pitching direction.…”

“…The experiment confirmed the results of the change in angle with windspeed to be within theoretical infinite and finite wing for small angles. More information of the experimental setup and validation can be found in Knight et al [43].…”

Fluid-Structure Interaction on The Design of Fully Assembled Shell Eco-Marathon (SEM) Prototype Car

“…Numerous FSI studies have been performed on various parts of vehicles on road, for instance, car spoilers [20,21], convertible car roof [22], or even the whole car in braking motion [23]. Kesti and Olsson [18] demonstrated fluid-structure interaction analysis with partitioned approach in both oneway and two-way coupling to analyse the underbody panels.…”