Integrated aerodynamic optimization design of convergent-divergent nozzle and vehicle afterbody

The aerodynamic characteristics of axisymmetric convergent-divergent nozzle and vehicle afterbody were studied. Based on the response surface method of orthogonal polynomials by combining with the self-programming, the three-dimensional flow field was numerically simulated. Flux coefficient and thrust coefficient were selected as the optimization indicators, while half convergence angle, throat radius, half expansion angle, bottom area and tail contraction angle were selected as the research objects to analyse under two conditions. By constructing and solving the function of response surface, the results show that half convergence angle and half expansion angle affect about 90% of aerodynamic characteristics; half convergence angle, throat radius and bottom area affect about 85% when discussing flux coefficient only; half expansion angle affect about 85% when discussing thrust coefficient only; half convergence angle, half expansion angle and throat radius affect more than 90% when discussing condition H=0 km, Ma=0 only; half convergence angle and half expansion angle affect more than 85% when discussing condition H=20 km, Ma=2 only.