Base pressure resulting from sudden expansion in cross-sectional area from a conical converging nozzle

This research concerns with the determination of the base pressure related to the conical convergent nozzle flow when a sudden enlargement in cross-sectional area occurs. It is recognized at the outset that the problem belongs to the category of strong interaction where inviscid and viscous flows must be considered together before a solution can be established. The viscous flow analyses based on the integral formulations are guided more or less by the boundary layer concept. The inviscid flow field is established from the hodograph transformation, and the method of characteristics. Again the point of reattachment behaves as a saddle point singularity for the system of equations describing the viscous flow recompression process. After the point of reattachment is approached, an overall momentum balance is applied so that the base pressure and the location where recompression starts, may be determined. Experimental studies with specific conical angles and area ratios are also conducted in the laboratory. The results obtained from the theoretical analysis agreed well with the experimental data produced in the laboratory and the data available elsewhere. These evidences lead to the conclusion that the method developed in this investigation is effective in dealing with problems of this type.