Reynolds number scaling at transonic speeds

Abstract

Abstract : This paper focuses on Reynolds number scaling (RNS) at transonic speeds for military aircraft development. RNS has been used in the development of aircraft for decades because most development wind tunnels have not had the capability of providing full scale flight Reynolds number. Any new, highly productive transonic wind tunnel that will provide duplicate flight Reynolds number up to 200 million (flight conditions of high performance aircraft) is not likely to be built because of high cost. Thus, this paper discusses the importance of RNS and why it must be used for the foreseeable future. Two empirical methods and one computational fluid dynamics (CFD) method are shown to illustrate some of the issues and deficiencies involved with RNS. Wind tunnel effects on aerodynamic data that produce pseudo Reynolds number effects and that must be taken into account are also discussed. Finally, it is argued that improvements in RNS and proper accounting for wind tunnel effects on aerodynamic data can significantly contribute to the reduction in the time and cost of aircraft development.