Aerodynamics of a Swept Wing with Ice Accretion at Low Reynolds Number

Abstract

This paper discusses the use of several experimental techniques to investigate the performance and flowfield of a swept wing with leading-edge ice at low Reynolds numbers. Force balance measurements were made over a range of angles of attack and Reynolds numbers. Surface oil visualization and pressure sensitive paint were used to investigate the flow over the surface of the wing, while five-hole probe wake surveys were used to investigate the wake. The flowfield of the iced swept wing was dominated by a leading-edge vortex that formed at low angles of attack due to separation from the tip of the ice shape, while for the clean wing a vortex did not form until higher angles of attack. The effect of Reynolds number on the performance and flowfield was also investigated.

Wake-Survey Technique for Iced Swept-Wing Aerodynamics

“…The results indicate that, for a fixed CL, the ice shape results in a significant increase in the profile drag, whereas the induced drag is unaffected. In the surface oilfiow, not shown here, it was observed that the size of the region of separated flow, relative to the local chord, increased as the tip was approached [6,15]. The flow visualizations of Diebold and Bragg [15] and Diebold et al [6] showed a leading-edge vortex behind the ice shape that grows with angle o f attack.…”

“…Maskell [12] refined the work of Betz [11] by introducing the blockage velocity ub, which acts as a small correction for the effect of tunnel walls on the velocity. Detailed derivations can be found in numerous references [7][8][9]13], For this work, a semispan wing model was constructed and tested in the 2.8-by-4-ft low-speed wind tunnel at the University of Illinois. (2) and (3).…”

“…The ice shape simulation was created using NASA's LEWICE 3.0, a two-dimensional (2-D) ice accretion code, and 2-D strip theory as discussed by Potapczuk et al [16], It should be noted that the intent was not to create an ice shape simulation that accurately represents a complex ice accretion that would form on this wing in flight, but rather to create a simple ice shape simulation that would have a substantial More details regarding the model, the ice shape, and the methods used to reduce the 5HP datacan be found in work by Diebold and Bragg [15] and Diebold [13]. The ice shape simulation was created using NASA's LEWICE 3.0, a two-dimensional (2-D) ice accretion code, and 2-D strip theory as discussed by Potapczuk et al [16], It should be noted that the intent was not to create an ice shape simulation that accurately represents a complex ice accretion that would form on this wing in flight, but rather to create a simple ice shape simulation that would have a substantial More details regarding the model, the ice shape, and the methods used to reduce the 5HP datacan be found in work by Diebold and Bragg [15] and Diebold [13].…”

In-flight icing on unmanned aerial vehicle and its aerodynamic penalties

“…Figure 6 shows some details of the IM swept wing geometry. The wing is fully described in [10]. The following §ow parameter values were used: angle of attack 0 • , free-stream air pressure 10 5 Pa, and free-stream air velocity 49.1 m/s.…”

“…The Illinois Model (IM) swept wing has been considered. It is a version of the Common Research Model (CRM) and is fully described in [10]. The FLOWer code was chosen because of potential extension of our capabilities to other larger wings or faster §ight speeds.…”