Methane-Air Combustion Gases as an Aerodynamic Test Medium

The present paper gives a review of the major problems associated with the use of hydrocarbon-a ir combustion gases as an aerodynamic test medium. Condensation of water vapor is identified as the major problem, and actual experience is offered as evidence of its effects on aerodynamic flow parameters. Aerodynamic data obtained from tests in methane-air combustion gases are compared with theory and with data obtained on the same shapes in other test facilities using other test media. The comparisons indicate that data obtained in combustion gas compare well with data obtained in other test media. Nomenclature A = cross-sectional area CA = axial-force coefficient, axial force/g S CD = drag coefficient, drag/# S CL(t = slope of the lift curve at a = 0 Cm = pitching-moment coefficient, pitching moment/^ SI CN = normal-force coefficient, normal force/g S Cp = specific heat at constant pressure d = model diameter, cm / = characteristic length (model length) M = Mach number