Transonic flow in the throat region of annular supersonic nozzles

A theoretical and experimental investigation of flow in the throat region of annular supersonic nozzles has been conducted. The theoretical analysis consists of the formulation and development of an approximate, series expansion solution to the inviscid, irrotational governing equations. The resulting solution provides a direct means of analyzing the throat flowfields in a variety of two-dimensional nozzle configurations including axisymmetric, planar, and annular nozzles. Flowfield static pressure measurements have been obtained for four nozzle configurations, including a conventional axisymmetric nozzle and three annular ones. Half-section cylindrical models were constructed and mounted on a splitter plate whose surface corresponds to a plane of symmetry for the axisymmetric geometries under consideration. Measurements from a grid of pressure taps arranged on the splitter plate allowed the determination of the static pressure fields in the nozzle throats. For all four cases tested, it is found that the agreement between the theoretical and experimental results is quite good through a significant region of the throat. Only near the bounding walls in the throat inlet region is there a noticeable discrepancy for some of the cases.