Design and optimization of three-dimensional supersonic asymmetric truncated nozzle

Abstract

Three-dimensional supersonic nozzle is an important component of air-breathing hypersonic vehicles to produce thrust and lift force. Since the length of nozzle with ideal design is too long to meet the trim requirements of integrated air-breathing hypersonic vehicles, it is necessary to design a truncated nozzle to provide excellent aerodynamic performance. In the present study, an axisymmetric minimum length nozzle was firstly designed using method of characteristics. Then, streamlines trace technique with an offset circular entrance was adopted to extract the three-dimensional asymmetric nozzle. Nonlinear compression method was applied to compress the nozzle to a suitable length. Afterward, a surrogate-based optimization of three design variables, namely pressure ratio of nozzle’s exhaust to ambient, reserved initial expansion ratio, and average compression ratio was performed with the objectives of thrust and lift force, and a Pareto optimal front was therefore obtained. Numerical simulations were also made at six selected Pareto front cases to offer an insight into the flow fields. An infection point was observed in the Pareto front due to the maximum constrained length. The pressure ratio was found to be the most influential parameter, and the middle parts of Pareto front revealed better uniformity of exit flow.