Numerical study on effects of wind tunnel test parameters on scaled-down models of counter-rotating propfan

In order to develop aerodynamic design and validation techniques applicable to counter-rotating propfans， this study focused on a counter-rotating propfan. Through theoretical analysis， numerical simulation studies， and experimental validation， a comprehensive study was conducted on effects of wind tunnel test parameters on scaled-down models of counter-rotating propfans. The results show that under constant inflow conditions， there exists a critical threshold in geometric scaling ratio beyond which the performance of the counter-rotating propfan experiences a decline. Under identical Mach and Reynolds number conditions， the temperature’s impact on the aerodynamic characteristics of scaled-down test models is maintained within 1% deviation， enabling wind tunnel test to be performed at ambient temperature. When the Reynolds number falls below 1.25×106， the flow exits the self-similarity regime. Although low-Renolds-number conditions degrade the aerodynamic performance parameters of counter-rotating propfan scaled-down test models， no significant alteration in the spatial flow field structure has been observed， and the performance variation trends remain consistent. In contrast， Mach number discrepancies lead to substantial changes in flow field structure， consequently modifying the trend of characteristic curve. Considering the practical constraints of the wind tunnel， wind tunnels were conducted on a scaled-down test models under reduced Reynolds and Mach number conditions. The test results show good agreement with numerical simulations， thus validating the accuracy of the numerical calculations in this study.