A design method of multiple control points for hybrid airfoil based on the similarity of flow field in the leading edge of airfoil is proposed. The size of aircraft models that can be tested in icing wind tunnels is limited by the dimensions of the facilities in present it is an effective method to replace the large model with a hybrid airfoil to carry out the experiment. Note that for the IB case, the normal full-scale cut intercepts the aircraft side of body, so the full-scale airfoil was 12 extrapolated past the leading edge to allow the use of the 2D hybrid design computational. The characteristics of these full-scale normal airfoils and corresponding 2D hybrid designs are presented in Table 1. 2, and the corresponding hybrid airfoils were designed to be later used in the hybrid wing designs. For this project, three CRM65 normal cuts were chosen named IB (Inboard), MS (Midspan) and OB (Outboard), presented in Fig. The flap chord corresponds to 1/3 of the hybrid main element chord and is a modified NACA6412 with both gap and overlap of 1.5% of the total hybrid chord c. The main element airfoil presents a negative nose droop angle γ = -5.5°, seen by its high trailing edge and C m0 = -0.05. A flapped hybrid airfoil was designed for a single airfoil cut of the CRM65 located at spanwise position ƞ = 64% of the semispan (called Midspan model) with SF = 2, upper and lower extents in bold at x/c fs = 10%, illustrated in Fig. A more detailed discussion on the 2D hybrid airfoil design method is presented by Fujiwara et 12 al, where matching stagnation point location is shown to be of first order for matching full-scale ice shapes. Values of γ can be either positive or negative, while C m0 is 35,36 usually negative. A more negative C m0 will result in a more cambered aft section, therefore, increasing aft loading. The quarter-chord zero-lift pitching moment coefficient, C m0, 34 determines the camber line curvature of the aft of the hybrid section. A more positive nose droop angle causes a lower trailing edge elevation or more camber, shifting the load towards the aft of the hybrid. It determines the elevation of the trailing edge with respect to the full-scale chord line. The nose droop angle, γ, is the angle between the full-scale chord and the hybrid airfoil chord. The hybrid scale factor, SF, is defined as the full-scale chord divided by the total hybrid- model chord, representing the factor by which the baseline geometry is shortened. The upper and lower extents maintained from the full-scale geometry are based on the estimated full-scale impingement limits, and are given as a percent of the chord (including both the main element and flap). A hybrid airfoil presents the same full-scale leading edge as the reference geometry with a redesigned aft section that is considerably shorter than the full-scale. Both CFB and IFB were used as the target references when designing the 3D hybrid-wing models. The Clean Flight Baseline (CFB) is the set of aerodynamic solutions provided by Boeing using CFD RANS code 32,33 20 OVERFLOW, whose velocity fields were input to LEWICE3D to generate the Iced Flight Baseline (IFB) with droplet trajectories and ice shapes on the CRM65. In order to simulate these icing cases, aerodynamic flow solutions must first be generated, and then later those solutions are used by the ice accretion simulations. Six different aerodynamic conditions were identified, with different temperatures that led to a matrix of 17 icing conditions.
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