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.

Wind tunnel testing is a crucial method for studying aircraft flutter. Using heavy gas as the wind tunnel medium can mitigate the escalating issue of test models being overweight as advanced aircraft develop. This paper employs an analytical method for numerical calculations of three-dimensional (3D) wing flutter based on fluid–structure interaction (FSI). Flutter calculations for the Goland wing are conducted, and the results in the air medium are consistent with the literature. In contrast, significant differences in flutter behavior are observed in the heavy gas R134a medium. Compared to air, when the model reaches a critical state in R134a, the incoming flow velocity is lower, the incoming flow density is approximately 3 to 5 times air, and the incoming flow dynamic pressure is about 1.1 to 1.2 times that of air. The correction of heavy gas flutter data is crucial for wind tunnel testing. This paper proposes a correction method based on the unsteady transonic flow similarity law proposed by Bendiksen under quasi-steady conditions. Attempts are made to revise relevant published wind tunnel tests and heavy gas flutter calculation results. The transonic flutter similarity law effectively explains the flutter similarity of rigid models in both heavy gas and air media. Still, it fails in cases with highly reduced frequencies and low mass ratios, such as those encountered with flexible wings.