Some Effects of Reynolds and Mach Numbers on the Lift of an NACA 0012 Rectangular Wing in the NACA 19-Foot Pressure Tunnel

摘要

A short investigation was made in the NACA 19-foot pressure tunnel to determine the aerodynamic characteristics of a rectangular wing model constructed to NACA 0012 airfoil sections. The tests were run with the air in the tunnel at two different pressures: atmospheric (14.7 lb/sq in. abs.) and 35 pounds per square inch absolute. The Reynolds number ranged from 1,070,000 to 5, 250,000 for the tests at atmospheric pressure and from 1,960,000 to 8,240,000 for the tests at a pressure of 35 pounds per square inch absolute. The results indicate a marked compressibility effect on the lift coefficients, particularly the maximum lift coefficients, which increase up to a velocity of approximately 150 miles per hour (a Mach number of 0.19) and then decrease rapidly. The results also indicate that, in wind-tunnel testing to determine maximum lift coefficients, compressibility effects may be avoided by limiting the tunnel air-stream test velocity to about 125 miles per hour (a Mach number of 0.17).