Study of a Swept Wing with Leading-Edge Ice Using a Wake Survey Technique

Abstract

The aerodynamics of swept wings with leading-edge ice is very complex and not fully understood. Previous swept wing icing studies have only provided force balance measurements and/or qualitative flow visualization. In order to more fully understand the complex aerodynamics it is necessary to understand how the ice influences the drag breakdown and the spanwise distributions of lift and drag. This paper utilizes 5-hole probe wake surveys and a far-field analysis to decompose the drag into profile and induced drag components and to determine the spanwise distributions of lift and drag. It is shown that the leading-edge ice primarily influences the profile drag and the induced drag is relatively unaltered. Features observed in the lift and drag distributions are related to features seen in the wake as well as in surface oil flow visualization.

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.…”

“…The accuracy of the wake-survey technique was assessed by comparing the lift and drag measured by the force balance to that calculated from the wake. Despite the underprediction in drag, Diebold and Bragg [15] showed that the drag curve measured by the wake survey closely followed the drag curve measured by the balance. Due to the small size of the model relative to the tunnel cross section, the standard wall corrections to the force balance measurements were negligible and did not affect the observed trends.…”

“…For the drag, the average errors were 14.6 and 13.3% for the clean and iced wings, respectively [15]. The following results are intended merely to demonstrate how the wake-survey technique can be used to improve our understanding of iced swept-wing aerodynamics.…”

“…(2) and (3). The model was mounted directly to the tunnel floor; see Diebold and Bragg [15], The swept-wing model was a modified version of the Common Research Model [14], The important geometric characteristics are given Table 1.…”

“…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].…”