Numerical Simulation And Analysis Of Opposing Jet Flow Field

Aircrafts will encounter severe drag of aerodynamic heating when flying at a high speed.How to reduce drag and heat is one of the most important issues in the aircraft design.Opposing jet can reduce drag and aerodynamic heating. It is impossible to study opposing jet for improving the speed and reducing the heating. Following contents are mainly studied in this paper:(1) The free jet flow field is simulated by numerical method. According to study pressure ratio of mainly control parameters how to influence the free jet flow field to show that: free jet can generate the chain structure,every length of structure increases with the increase of pressure-ratio and reduces along the jet direction, the parameters as the sine wave distribute at the axis of the free jet, and the crest and the spacing of the crest gradually decreases, the parameters of free jet is equal with the flow field’s to keep balance finally, compression wave and expansion wave alternate at the axis of the free jet, the critical state can produce a minimum fluctuation and a maximum thrust.(2) The t flow field and stability of the opposing jet is simulated by numerical method. The results show that: a lower pressure ratio of the opposing jet can’t form a stable flow field,there is a chain structure near the nozzle as the free jet, the status which at a high mach reduce the drag better will product the bigger stagnation of mach-disk and bigger shock wave, the stable flow is relatively stable not absolute, it’s parameters oscillate weakly, the parameters of flow field oscillates cyclically.(3) The opposing jet flow field at angle of attack is simulated by numerical method to study the efficacy of reducing drag, and then proposing a scheme of combination of jet, The results show that: the opposing jet can well reduce drag at angle of attack, the larger the pressure ratio, the smaller the drag coefficient, the drag coefficient increases with the increasing the angle of attack, the difference value of parameters such as pressure, density and temperature on the up and down surfaces increases with the increasing the angle of attack, combination of jet drag reduction effect and stability is better than the old opposing jet.