The transonic flow problem is important practically in all areas where supersonic nozzles are used, Much difficulties are encountered during theoretical and experimental investigations of the critical section for nozzles with normalised radius of curvature tending to zero. Investigations have shown that the wall curvature has a great influence on:1) the un uniformed nature f the flow along the critical section 2) the form and position of the sonicline and 3) the flow rate coefficient .These observations have made it possible to propose the present method and to propose a parameter by which it is possible to generalise experimental results of plane and axisymmetric nozzles. Comparisons of results by the proposed method with experimental results of different authors and of different laboratories show good agreement. Therefore, the proposed method can be used for solving the direct problem of the transonic flow inplane ana axisymmetric nozzles for all values of throat curvature. © 1991 by the American Institute of Aeronautics and Astronautics. Inc. All Rights Reserved.