Research On Surface Cooling Characteristics Of Plug Cone In 2-D Plug Vectoring Nozzle

2-D plug nozzle is one of the mechanical thrust vectoring nozzles,which has an application prospect due to its superiority in the infrared suppression and vector trust.As the plug is located at the trailing of nozzle,an effective cooling on the plug rear-body is necessited for reduing the surface temperature and thus the infrared intensity.In addition,the plug front-body suffers to serious impingement of hot gas.Therefore,an effective cooling is also needed for thermal protection on the plug front-body from over-heating,especially at the leading egde of the plug.The current study involves in the following main contents.The numerical simulations are firstly performed to illustrate the aerodynamic and infrared radiation performances of 2-D plug nozzle.The results show that pneumatic vector angle is a little less than the geometric vector angle during the vector deflection.In the situation of no vectoring deflection,the nozzle has a trust coefficient of about 0.94 and a total pressure recovery coefficient of 0.87.In comperasion with no vectoring case,the trust coefficient and total pressure recovery coefficient in the vectoring situation with 20 degree deflection are decreased approximately 0.49% and 0.42% respectively.In the horizontal detective plane,the total infrared radiation intensity in the detective range of 0? and ±30? is gradually decresed as the increase of vector deflection angle.Aiming at the structural features of the plug cone front edge,a cooling structure combining the impingement cooling at the leading edge and the film cooling at the straight segment of the plug cone is proposed.The cooling characteristics of the cone surface and the aerodynamic performance of the nozzle are numerically studied.The results show that the increase of blowing ratio,perforated percentage and the vector deflection make the total pressure recovery coefficient and trust coefficient of the nozzle decrease.As increase of blowing ratio and perforated percentage,the discharge coefficient of film hole is increased and the overall cooling effectiveness is enhanced.While the increase of film-cooling-hole inclination decreases the overall cooling effectiveness.In view of the structure of the trailing edge of the plug cone and the characteristics of the flow field in the nozzle outlet section,a cooling structure combining the impingement cooling at the inner surface of trailing edge and the film cooling at the outer surface of the plug cone is proposed.The cooling characteristics of the cone surface as well as the aerodynamic and infrared radiation performances of the nozzle are numerically studied.The results show that the thrust coefficient and the total pressure recovery coefficient of nozzle decrease with the increase of blowing ratio,perforated percentage,the inclination of the hole and vector deflection angle.The decrease of infrared radiation intensity in the vertical detective plane as the increase of blowing ratio and perforated percentage is more obvious than that on the horizontal detective plane.Under the same cooling air usage,the arrangement of film cooling holes seens has a littlte influence on the infrared radiation intensity distribution.Finally,an experimental study is performed for some typical 2-D plug nozzle scale models.The influence of structural parameters and cooling scheme on surface cooling characteristics of the plug cone is analyzed.The results show that the film-hole arranement with a less perforated percentage is more benefit for producing high cooling effctiveness under a little cooling air usage.However,given a big cooling air usage,the film-hole arranement with a bigger perforated percentage seems to be more advantagous.The cooling scheme by integrating jet impingement improves effectively the unimormity of temperature distribution on the plug surface.