Investigation Into Essential Problems Of Detonation-Driven Shock Tunnel JFX

The development of hypersonic technology needs the advanced ground test facilities.The detonation-driven shock tunnel has been the most promising facility because of its unique advantages.This paper introduces the new detonation-driven shock tunnel JFX in Institute of Mechanics,Chinese Academy of Sciences.Combining the experiments and the numerical simulation,researches several key problems which impacting on the performance of detonation-driven shock tunnel such as diaphragm rupture by dual ignition,shock tube conditions and characteristics of the test flow.The main contents are summarized as below:(1)Compare the performance of JFX shock tunnel in different operation modes,backward-running mode and forward-running mode.Studied on the influence of performance of JFX shock tunnel in dual ignition mode with different ignition delay time.The results show that the dual ignition system can burst a metal diaphragm without its fragmentation.The different ignition delay time is majorly influence the effective test time.It would obtain the ideal shock tube conditions by controlling the ignition delay time.(2)The parameters of tailored condition were obtained for the detonation-driven shock tunnel through experiments and numerical simulation.Analyze the driving capacity loss caused by diaphragm rupture and the influence factors,also the effect to performance of shock tube.The results indicate that the JFX can provide the airflow that total temperature up to 5400 K and stagnation pressure up to 12.5MPa in tailored condition and the effective test time is nearly 6ms.The material,aggregate thickness and effective thickness are the main influencing factors for pressure loss.It is necessary to revise the parameters of stagnation airflow when the pressure loss is remarkable.(3)Designed the contoured nozzle for JFX detonation-driven shock tunnel.Subsequently,The flow field and its non-equilibrium characteristics of a contoured nozzle were simulated by CFD++.The results show that the airflow of nozzle exit is thermal and chemical non-equilibrium at tailored condition.The flow filed is frozen behind the throat by0.5m,component concentration and the vibrational temperature were almost unchanged;the parameters of flow flied would be changed markedly when take into account the pressure loss caused by diaphragm rupture.