Effect of internal pylons on the parameters of the jet flow in a nozzle with a central body

A high-velocity flow in an axisymmetric nozzle containing a central body and pylons is studied. The influence of the geometry of the main and additional pylons on the gas-dynamic and thrust characteristics at the nozzle exit in the flow regime with $n_{pr}=2.25$ ($n_{pr}$ is the ratio of the pressure in the settling chamber to the ambient pressure) is determined. Azimuthal nonuniformity of the flow at the nozzle exit is detected. The maximum azimuthal nonuniformity is observed in the wake behind the pylons. It is shown that a three-dimensional transonic flow is formed in the nozzle duct with the pylons mounted in the minimum free-area cross section; local supersonic regions closed by weak shock waves are formed in this flow. It is found that the formation of such a shock wave structure is responsible for nozzle thrust reduction by 12%.