NLR 7301 Supercritical Airfoil Oscillatory Pitching and Oscillating Flap
Abstract
The supercritical airfoil NLR 7301 has a maximum thickness of 16.5 per cent of the chord. In the Set of two-dimensional aeroelastic configurations this airfoil represents the category of thick and blunt-nosed airfoils. The airfoil was investigated in two windAtunnel tests with different models. In the first test the model could be driven harmonically in a pitching motion about an axis at 40 per cent of the chord. Information about this configuration is designated with the letter "A". In the second test harmonic rotation of a trailing-edge flap was considered. The flap axis was located at 75 per cent of the chord; the flap had no aerodynamic balance. Information about this configuration is designated with the letter "B,,. In transonic flow the contribution of the shock to the aerodynamic loading can of course be very different. As an illustration, pressure distributions on the upper surface are compared for a flow with a strong shock and a shock-free flow. Also results of thin-airfoil theory have been added. In the strong shock cases (A: Fig. 1, B: Fig. 5) the pressure peak due to the moving shock dominates in the pressure distribution, with a strength which diminishes with frequency. Although the flow conditions are the same for both configurations, the mean pressure distributions differ slightly. The cause of these differences could not be traced. In the shock-free cases (A: Fig. 2, B: Fig. 6) the pressure distribution shows a wide bulge. The pressure distributions of configuration A show very clearly that with increasing frequency the bulge decreases while at the same time a weak shock develops. Also here the mean pressure distributions should be the same. For unexplained reasons, however, shock-free flow could only be realized at slightly different Mach numbers. Lift and moment coefficients are presented in figures 3 and 4 for configuration A and in figures 7 and % for configuration B. The influence of fixing boundary layer transition is remarkable.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 2000
- Accession Number
- ADP010708
Entities
People
- R. J. Zwaan
Organizations
- National Aerospace Laboratory