Innovation of the experimental facility for the study of flutter in the Institute of Thermomechanics AS CR and some results obtained from initial experiments

摘要

The wind tunnel of a suction type was used for experiments with the fluttering profile NACA0015. Profile has two degrees of freedom, one in rotation (pitch) and the second one in translation mode (shift). Torque elasticity was realized by the coil spring and changed by the spring length and diameter of the spring wire. The pitch angle of the profile was measured by the magnetic rotary encoder. The translation was indicated by the magnetic linear encoder and was centered by plane springs situated on both ends of the shiftable frame. With this model the testing measurement of the self-excited vibration of flutter type in the range of Mach numbers M = 0.20-0.215 and Reynolds numbers Re = (2.63-2.83)·10~5 was realized. Results obtained for M = 0.21 and Re = 2.76·10~5 are presented. The measurement was adapted for the flow field evaluation by optical methods. Turbulence level was approximately 0.6%.