Advances in critical technologies for hypersonic and high-enthalpy wind tunnel

Hypersonic and high-enthalpy wind tunnels and their measurement techniques are the cornerstone of the hypersonic flight era that is a dream for human beings to fly faster,higher and further.The great progress has been achieved during the recent years and their critical technologies are still in an urgent need for further development.There are at least four kinds of hypersonic and high-enthalpy wind tunnels that are widely applied over the world and can be classified according to their operation modes.These wind tunnels are named as air-directly-heated hypersonic wind tunnel,light-gas-heated shock tunnel,free-piston-driven shock tunnel and detonation-driven shock tunnel,respectively.The critical technologies for developing the wind tunnels are introduced in this paper,and their merits and weakness are discussed based on wind tunnel performance evaluation.Measurement techniques especially developed for high-enthalpy flows are a part of the hypersonic wind tunnel technology because the flow is a chemically reacting gas motion and its diagnosis needs specially designed instruments.Three kinds of the measurement techniques considered to be of primary importance are introduced here,including the heat flux sensor,the aerodynamic balance,and optical diagnosis techniques.The techniques are developed usually for conventional wind tunnels,but further improved for hypersonic and high-enthalpy tunnels.The hypersonic ground test facilities have provided us with most of valuable experimental data on high-enthalpy flows and will play a more important role in hypersonic research area in the future.Therefore,several prospects for developing hypersonic and high-enthalpy wind tunnels are presented from our point of view.

Optimization of the MUSCL scheme by dispersion and dissipation

A second-order optimized monotonicity-preserving MUSCL scheme(OMUSCL2) is developed based on the dispersion and dissipation optimization and monotonicity-preserving technique.The new scheme(OMUSCL2) is simple in expression and is easy for use in CFD codes.Compared with the original second-order or third-order MUSCL scheme,the new scheme shows nearly the same CPU cost and higher resolution to shockwaves and small-scale waves.This new scheme has been tested through a set of one-dimensional and two-dimensional tests,including the Shu-Osher problem,the Sod problem,the Lax problem,the two-dimensional double Mach reflection and the RAE2822 transonic airfoil test.All numerical tests show that,compared with the original MUSCL schemes,the new scheme causes fewer dispersion and dissipation errors and produces higher resolution.