Geometric Effects Analysis and Verification of V-Shaped Support Interference on Blended Wing Body Aircraft  
[PERSON]  
1 State Key Laboratory of Aerodynamics, Minyang 621000, China; [EMAIL_ADDRESS] (X.X.); [EMAIL_ADDRESS] (Q.L.); dehch@sina.  
Among the above-mentioned support forms, the tail sting support, which is the most commonly applied primary support form in high-speed wind tunnels, meets the test requirements in both longitudinal and horizontal directions [27; 28; 29].  
In recent years, the blended wing body (BWB) layout has been considered to be the best choice for aircraft of the next generation [30; 31; 32]. The wing and body of BWB aircraft are highly integrated so that there is no obvious fuselage. The aerodynamic efficiency of BWB aircraft is 20% higher than that of conventional-layout aircraft [33]. In order to take advantage of high aerodynamic efficiency, the test accuracy of BWB aircraft must be higher than that of conventional-layout aircraft; therefore, the support system of BWB aircraft should be designed in detail. Accurate aerodynamic characteristics of the full model cannot be obtained by wing tip double support or vertical tail support, while the requirements of the horizontal test cannot be met by blade support/sidewall support or vane cable suspension support [34; 35; 36; 37]; therefore, all of these can only be applied as auxiliary support. The basis aerodynamic testing of BWB aircraft still needs to use tail sting support as the primary support form. However, the design of a tail sting support system is quite difficult because of the unconventional configuration of BWB aircraft. On one hand, the internal space of a BWB aircraft's central body is rather limited and the trailing edge is quite thin, with the result that the test model distortion by traditional straight tail support cannot be avoided, making it almost impossible to correct the support interference [38]. On the other hand, the exhausts of the engine and ailerons are located near the trailing edge. As a result, complex flows, such as the coupling of internal-external flows and the separation of the vortex, may be influenced by traditional straight tail support, which is quite different from conventional-layout aircraft [39]. Therefore, the existing design method of tail support, which is established for conventional-layout aircraft, is not suitable for BWB aircraft. The dedicated tail sting support must be redesigned to meet the test requirements of BWB aircraft, but there exists no specification and prior experience to follow in doing this.  
Although various support systems have been designed, they are not suitable for wind tunnel testing of BWB aircraft. Thus, a special V-shaped support for BWB aircraft was designed by the high-speed institute of the CARDC. An investigation into V-shaped support has not yet been observed, and the support interference characteristics and design criteria need to be studied. The transonic flow of BWB aircraft with different V-shaped supports were numerically simulated in this study. The interference characteristics of V-shaped support were analyzed, and the geometric parameter influences of V-shaped support on aerodynamic interference were obtained. According to the numerical results, the corresponding dummy V-shaped supports were designed and manufactured, and the verification test was conducted in a 2.4 m \(\times\) 2.4 m transonic wind tunnel. The test model was manufactured with material F141, which is considered to be stiff enough for aeroelastic deformations of the test model to be quite tiny. Thus, the aerodynamic interference could be validated; however, the flutter characteristics of BWB aircraft are not detailed in this paper. For a test model made of other materials, the flutter characteristics of BWB aircraft could be analyzed using the method in reference [40]. This research could be used as a reference while designing special V-shaped support for BWB aircraft in high-speed wind tunnels, which could reduce support interference and improve accuracy of test results.