| Vane/Cable suspension support system (VCSSS) causes less distortion to the model and has high longitudinal stiffness, and high test precision. It is an ideal support mechanism for large aircraft wind tunnel tests. Recently, the VCSSS test technique has been developed in 2.4m transonic wind tunnel of CARDC. It will contribute much to this technique application in large aircraft wind tunnel tests and improve the design skills of large aircraft that deeply investigating on the interference characteristics of VCSSS.Wind tunnel tests and numerical simulation (CFD) methods were adopted to investigate on the interference characteristics of VCSSS and its interfering mechanism using Ty154 calibrating model. The sting support was mainly used to obtain the VCSSS interference through testing the model with and without "fake vanes". A high stiffness post-sting was designed to avoid the serious vibration of model, which would cause the model collision with "fake vanes". Similar to the test scheme, CFD methods were applied to simulate the flow field over Ty154 model with and without vanes, thus integrating to get interference quantities. Reynolds averaged N-S equations were solved using S-A turbulence model and Roe scheme was used as the spatial discretization method while LU-SGS used as time discretization scheme. During the test process, the incidence and relative location of model varied with the vanes as the angle of attack changed, therefore, different grids were needed to generate for different angles. To improve the efficiency of grid generation, structural chimera grids technique was brought into use. Besides, different support frameworks and their combination were also simulated to compare with VCSSS.Through analyzing the wind tunnel tests and CFD results, the following conclusions could be obtained.1. The interference characteristics of VCSSS acquired through wind tunnel tests and CFD methods compared well. When M≤0.90 and a≤6°, the interferences are quite small. VCSSS shows obvious advantages over ppst-sting and blade support. Generally, the lift of model decreased a little while the drag and pitch increased interfered by VCSSS. The interference law turned random at high angles. On the condition of subsonic and lower transonic, the interference quantities scarcely changed with Mach numbers, while the interference law turned complicated at higher speed.2. The interference effects of the front and back vanes were independent. At lower angles, the drag and pitching moment of model were mainly interfered by front vanes, while the back vanes contributed the main interference quantities at higher angles. Front vanes influenced the symmetry plane of front fuselage mainly, resulting in a nose up pitching moment. Back vanes showed some effect on the aft-fuselage, trailing edge of wing root and the leading edge of horizontal empennage. The pressure of trailing edge of wing slightly increased, but it did not change the integral aerodynamic force much. The interference of back vanes to leading edge of horizontal empennage was quite small, but it contributed much to the general interference of pitching moment.3. The interference zone of the crack around the joint of front vanes and fuselage was quite small, and barely influenced the general aerodynamic force of the plane. The pole of back vanes will enlarge the interference of back vanes to the fuselage and wing; but it will eliminate the interference of the whole vanes in pitching moment.4. The interference of VCSSS could be reduced through placing the front vane backer and making the back vanes nearer the aft-fuselage while designing the test scheme5. The VCSSS technique was successfully applied in wind tunnel test of a large aircraft, and the test results compared well with post-sting support test data. Besides, as the VCSSS has higher stiffness, it shows some advantages in predicting the separation angles of large aircraft. It also serves well as an auxiliary support in accessing the interference quantity of sting support struts. |
PDF Full Text Request