Effect of non-equilibrium condensation on lift divergence Mach number at transonic speeds

Abstract

In the present paper, the effects of non-equilibrium condensation on the lift divergence Mach number with the angle of attack in a transonic 2-D moist air flow of NACA0012 are investigated using a numerical analysis with a total variation diminishing scheme. In the case of T ₀ = 298 K and α = 3°, the lift divergence Mach number M _ld decreases with increasing Ф ₀ up to 40%, whereas beyond Ф ₀ = 40%, the lift divergence Mach number is nearly constant at M _ld = 0.75. On the other hand, for the case of α = 6°, M _ld increases with increasing Ф ₀ up to 47%, and then M _ld begins to decrease with an increase in Ф ₀. Because of the attenuating effect of non-equilibrium condensation on the shock stall, for the case of α = 3°, C _L generally decreases with an increase in Ф ₀, whereas for M∞ = 0.85, which is appreciably larger than the lift divergence Mach number, C _L increases with an increase in Ф ₀. In the case of M∞ = 0.85, regardless of Ф ₀, it is shown that the location of the maximum Mach number at the upper wall side is nearly constant at x/c = 0.4. It is found that the Mach number for the minimum C _L decreases with an increase in Ф ₀.