CFD/CSD-based flutter prediction method for experimental models in a transonic wind tunnel with porous wall

To predict the flutter dynamic pressure of a wind tunnel model before flutter test,an accurate Computational Fluid Dynamics/Computational Structural Dynamics(CFD/CSD)-based flutter prediction method is proposed under the conditions of a 2.4 m×2.4 m transonic wind tunnel with porous wall.From the CFD simulations of the flows through an inclined hole of this wind tunnel,the Nambu's linear porous wall model between the flow rate and the differential pressure is extended to the porous wall with inclined holes,so that the porous wall can be conveniently modeled as a boundary condition.According to the flutter testing approach for the current wind tunnel,the steady CFD calculation is conducted to achieve the required inlet Mach number.A timedomain CFD/CSD method is then employed to evaluate the structural response of the experimental model,and the critical flutter point is obtained by increasing the dynamic pressure step by step at a fixed Mach number.The present method is applied to the flutter calculations for a vertical tail model and an aircraft model tested in the current transonic wind tunnel.For both models,the computed flutter characteristics agree well with the experimental results.

Study on the Numerical Model of Transonic Wind Tunnel Test Section

The authors consider numerical simulations of transonic flows through various turbine cascades in a confined channel which approximates boundaries of real wind tunnel.The boundaries of the wind tunnel are impermeable or there can be permeable tailboards to diminish shock wave reflections.The mathematical model is based on Favre-averaged Navier-Stokes equations closed by a turbulence model and model of transition to turbulence.The mathematical model is solved by an implicit finite volume method with multi-block grids.Several types of turbine blade cascades with subsonic or supersonic inlet are presented.The results are compared with optical measurements and simulations of periodic cascades.The validity of experimental reference flow parameters in relation to computed flow patterns is discussed.

Loads Analysis of Flanges of a Transonic and Supersonic Wind Tunnel Wide Angle Diffuser

Compared with general circular flanges, flanges on conical shells have different configurations. In the Chinese national code GBISO, however, there are no related contents about flange design of this kind of type. So, it needs to study loads of flanges of this kind of type. This paper takes the flange connection of a wide angle diffuser in a transonic and supersonic wind tunnel as the background, according to the principles of flange design in Chinese national code GB150, combining the characteristics of flanges of a wide angle diffuser, the loads of flanges have been analyzed, and the equations of loads and their locations have been presented.

TRANSONIC WALL IN TERFERENCE CORRECTIONS FOR CIVIL AIRCRAFT MODEL TESTS

The correction method uses the static pressures measured near the tunnelwalls during model tests as boundary conditions. It is required that the flow near thewalls is subsonic and the freestream Mach number is less than 1. It is still valid whenthere are shock waves and supersonic pockets near the model as long as shock waves donot extend to walls, and the method is applicable to various ventilated wall or solid walltest sections. Corrections for three models tested abroad are in quite good agreementwith NASA's results, which are obtained by a nonhnear correction method. Thepresnet method has been apphed to B737 inodel tcsted in CARDC 1.2 m wind tunnel.The results show that this method is suitable for transonic wall interference correctionfor high aspect ratio airplane tests.