Transonic flutter computations for a 2D supercritical wing

Abstract

A n umerical investigation of the transonic twodegree-of-freedom bending/torsion utter characteristics of the NLR 7301 section is presented using a time domain method. An unsteady, t wo-dimensional, compressible, thin-layer Navier-Stokes ow-solver is coupled with a two-degree-of-freedom structural model. Furthermore, the Baldwin-Lomax, the Baldwin-Barth and the Spalart-Allmaras turbulence models are implemented, each in conjunction with the transition model of Gostelow et al. The transition onset location can either be predicted with Michel's criterion or speci ed as an input parameter. Computations of the steady transonic aerodynamic characteristics show good agreement with the experimental results using the BaldwinBarth or the Spalart-Allmaras model in combination with transition modeling. The aeroelastic computations predict limit-cycle utter in agreement with the experiment. However, the computed utter amplitudes are an order of magnitude larger than the measured ones.

Parallel Computation of Wing Flutter with a Coupled Navier-Stokes/CSD Method

“…Numerical investigations on the transonic test case MP77 (nominal M ∞ = 0.768, α = 1.28 • and Re = 1.7·10 6 ) have been performed in the time-domain by a number of authors. [27][28][29][30] The common result in those investigations is the prediction of limit-cycle flutter at amplitudes one order of magnitude larger than those observed in the experiments.…”

“…Similar observations are made in Refs. [26][27][28][29][30]. Further investigations are needed to resolve those issues, given that generally speaking flows over many other airfoils have been well predicted by modern Navier-Stokes computations, at least for steady-state solutions.…”

Transonic flutter computations for the NLR 7301 supercritical airfoil

“…It was shown by Weber et al [24] that during this period the shock on the suction side becomes stronger and moves upstream causing a shock induced separation. After reversal of the pitch motion, a smooth pitching moment coefficient variation is predicted up to the highest pitching moment coefficient.…”

Simulation of transonic limit cycle oscillations using a CFD time-marching method

“…As mentioned before, the As shown in [13][14], because of the relatively large chord length of the airfoil with respect to the wind tunnel test section (1 m x 1 m), both the freestream Mach number and the angle of attack need to be corrected to take into account wind tunnel wall effects. Figure 4, the resultfrom Eulercomputation overpredicts the shockstrength.…”

“…The criterionusedin [13][14]wasto matchthe computed to the measured time-averaged surface pressure distribution. Note that the off-diagonal terms in the damping matrix are assumed to be zero for simplicity.…”