Effects of gap width between nozzles on linear plug nozzles performance

To understand the effects of gap width between nozzles on linear plug nozzles performance, three plugs with different wide gaps were brought forward, which were fixed on the same inner nozzle. Numerical method was employed. Flowfields and performances of plugs with different gaps were obtained. Ways of gap width affecting linear plug nozzles' performance were found: increasing of gap width could augment linear plug nozzles' area ratio and design pressure ratio, decreasing pressure on plug surface and performance of linear plug nozzles. When gap width was augmented twice, performance of linear plug nozzles was reduced by 1% - 3%. In addition, it is found that performance of inner nozzle is the largest part of that of linear plug nozzles, accounting for more than two thirds of whole engine's performance.