A Study on the Two-Dimensional Numerical Simulation of Wing Flutter in a Heavy Gas

Using heavy gases in wind tunnel tests can reduce model weight issues, which have intensified with advancements in high-performance aircraft technology. This study employs time-domain analysis to examine the flutter characteristics and correction methods of a 2D airfoil under heavy gas conditions; it also examines how structural dynamic similarity parameters influence wind tunnel flutter tests and the effect of structural parameters on the flutter boundary of heavy gases. The results are as follows: 1. The same model reaches the critical state in air, while its vibrations converge in heavy gas. Under consistent temperature and pressure, structures in R134a exhibit harmonic vibrations with the natural frequency reduced to 46~48% of that in air. 2. With the same incoming flow Mach numbers, designing the R134a medium model based on reduced frequency similarity results in a 20% reduction in flutter pressure compared to air. Adjusting the Mach number for R134a according to similarity parameter χ shows that its dimensionless flutter dynamic pressure is about 10% lower than that of air. 3. We investigate the impact of specific heat ratio variations on heavy gas flutter and establish a similarity law for heavy gas flutter based on the similarity parameters χ and ψ. The similarity law for heavy gas flutter explains well the flutter similarity between air and R134a at different mass ratios. However, correction errors at low mass ratios and high reduced frequencies indicate that a more precise correction method is still needed for further development.