Capability Analysis of Global Hypersonic Wind Tunnel Facilities for Aerothermodynamic Investigations

Abstract

Much of the work in the field of aerothermodynamics focusing hypersonic vehicles is underway in different parts of the world, yet a comprehensive review of all hypersonic wind tunnel facilities is missing from literature. Current study addresses this research gap by reviewing all existing and operational hypersonic wind tunnels of the world. Aerothermodynamic vehicle has peculiar design features with varying performance parameters as they pass through different flight regimes during single flight operation. Ascent to space and reentry back into atmosphere being the two most important flight regimes any such vehicle pass through. Maximum dynamic pressure during exit for space and total heat flux going into the vehicle surface during reentry are critical measurements to be undertaken inside ground facility during initial design phase. Hypersonic regime has thermodynamic and chemical processes, which dominate energy transfer between medium and re-entry vehicle. Measurement of performance parameters remained a challenge for at least half a decade. Researchers are facing difficulties in measuring accurate and reliable data from wind tunnels conducting experiments at hypersonic speeds. The operational facilities can meet Mach and Reynolds numbers requirements but noise levels, binary scaling parameters, capturing non-equilibrium phenomenon are to name few which pose real challenge to designers of this age. This research reviews basic types of existing hypersonic wind tunnel facilities and presents a comparative study of world's famous hypersonic ground test facilities which have shown significant contribution towards research and development activities in the field of aerothermodynamics. This study will be helpful in identifying correct facility for any aerothermodynamic research to be undertaken in future. It is concluded that no real time hypersonic wind tunnel exists in world today which can be run for long durations and have all physical phenomenon of hypersonic flow. There are several technological complications still present today which includes maintaining high stagnation temperatures for long duration, large test sections, lacking of physical flow features around tested vehicle like think shock layer, entropy layer, viscous interactions and capabilities for large angle of attack parametric variation.