Analysis of the aspiration drag in dual-bell nozzles during separation operating mode
The performance of dual-bell nozzles is affected by the aspiration drag generated in the recirculation zone during low-altitude operation.Dual-bell nozzles with different design parameters were studied by simulation to gain the aspiration drag at various flight altitudes.Results show that the aspiration drag does not always decrease with the increasing flight altitude as existing research reported.The aspiration drag of dual-bell nozzles with negative wall pressure gradient extension decreases with increasing flight altitude,while the aspiration drag of dual-bell nozzles with zero and positive wall pressure gradient extensions firstly decreases and then increases with the increase of flight altitude,and the inflection altitude appears at 2 km.These phenomena are caused by opposite varying trends for the axial size of the recirculation zone and the difference between the ambient pressure and the wall pressure in the recirculation zone during the ascent of flight altitude 0-8 km.Moreover,the aspiration drag can be reduced by increasing the length and area ratio of the base section and decreasing these parameters of nozzle extensions,the reduction in drag coefficient is about 1%-2%.
国家科技期刊平台
NSTL
万方数据
维普
