Hypersonic air-breathing propulsion is one of the key techniques for future aviation and the ground aerodynamic testing for full scale test models with sufficient test time at flight conditions is of fundamental importance for verifying hypersonic air-breathing engines.Based on the backward detonation-driven concept,the hypersonic flight-duplicated shock tunnel(or JF-12 shock tunnel)has been successfully constructed and calibrated.This facility is capable of reproducing airflow for Mach numbers ranging from 5 to 9 at an altitude of 25-50 km,with a test duration of more than 100 ms.To quantify the performance of the shock tunnel,experiments were conducted to investigate the aerodynamic characteristics of the test flows and the effects of several critical techniques that play important roles in the operation of the shock tunnel.The stagnation pressure was constant within±5％and the average stagnation pressure varied by less than 0.048％/ms.The variation of the stagnation pressure in repeated experiments is less than 2.0％,indicating the good repeatability of the wind tunnel.The non-uniformity of the Mach number in the core flow field at the nozzle exit was within±2.5％.Additional,a uniform flow field is established upstream of the nozzle exit.The axial gradients of the flow field are small since the Mach number varies less than 1.7％/m.Findings regarding the ignition technology,diaphragm ruptures,detonation driver capacity,incident shock-wave decay,and tunnel operation mode are also presented.The findings of this study are not only helpful for operating the shock tunnel,but can also assist the future development of hypersonic wind tunnels.
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