Design, integration and characterization of a Mach 5 axisymmetric contoured nozzle for the VKI-H3 hypersonic tunnel

In pursuit of advancing the capabilities of ground testing facilities, a complete road map for broadening operational range of the H3 hypersonic blowdown wind tunnel, operated at the von Karman Institute for Fluid Dynamics (VKI), with the addition of a new Mach 5 contoured nozzle is constructed. The main characteristics of the facility are presented. The supersonic ejector is identified as a critical component defining the current operational boundaries. The different operating regimes of this device are analyzed and its performance characteristics are accounted for as the new nozzle is designed. The methodology used to design a high-quality axisymmetric contoured nozzle enabling operation at Mach 5 and high Reynolds numbers is reported. A parametric design space is generated for the new nozzle focused on the nozzle opening angle and its transition length which allowed the identification of the optimum set of design parameters. Then a viscous correction comprised of empirical predictions and Navier-Stokes computations of the nozzle flow expansion is performed. The numerical analysis also served to quantify the expected radial and axial flow uniformity within the core flow. Upon manufacturing, instrumentation and integration of the Mach 5 nozzle, an extensive commissioning campaign is initiated. The flow investigations rely on several intrusive and non-intrusive measurement techniques including free-stream static pressure probes, pitot pressure rake and schlieren flow visualization. The Mach 5 freestream conditions within the core flow are confirmed with an uncertainty range of 0.2%. An exceptional radial and axial flow uniformity (>99.7%) is reported across the core flow, in close agreement with the predicted numerical performances. • A complete road map for broadening the operational range of the VKI-H3 hypersonic blowdown wind tunnel is constructed. • Operating regimes and the performance constraints of the supersonic ejector are accounted for as the new nozzle is designed. • A new Mach 5 axisymmetric contoured nozzle is designed using the in-house hypersonic nozzle design tool HYPNOZE. • An extensive commissioning campaign utilizing of several intrusive and non-intrusive measurement techniques is conducted. • The Mach 5 freestream conditions within the core flow are confirmed with 99.7% flow uniformity in the test section.