Reynolds Number Effects on Transonic Aerodynamic Characteristics of the CHN-T1 Standard Model

Abstract

Experimental data at flight-relevant Reynolds numbers remain scarce for publicly available transport aircraft standard models. This study analyses Reynolds number effects on the CHN-T1 large-aspect-ratio configuration using measurements from the cryogenic European Transonic Wind Tunnel, covering Mach 0.20–0.90 and unit Reynolds numbers from 3.6 × 106 to 37.8 × 106. A split transition strategy (fixed at low Re, free at high Re) is employed; the resulting trends are smooth and physically consistent with boundary-layer stability behaviour across the configuration change. At the cruise condition (M = 0.78), the non-induced drag coefficient CDV follows a power law CDV ∝ Re−n with n = 0.141, corresponding to about 70% of the canonical turbulent flat-plate exponent n = 1/5. At off-design Mach numbers, the exponent reduces to n = 0.126 (M = 0.60) and n = 0.125 (M = 0.85), reflecting growing pressure and wave drag contributions that scale more weakly with Reynolds number. The longitudinal static stability margin also exhibits a measurable Re dependence at the cruise condition, with the neutral point shifting aft by approximately 1% of the mean aerodynamic chord over the tested range. These findings provide quantitative benchmarks for Re scaling methodologies and CFD validation at flight-relevant conditions.