A Review of the History of the NACA Centrifugal Compressor Program and Arrival at Current Computational Design Procedures

Before and during World War Il the design and development of single stage, high pressure ratio centrifugal compressors was essentially a cut and try exercise. To reach a high pressure without substantial experimentation required multiple stages of impellers and diffusers with pressure ratios in the two to one range. While such arrangements were satisfactory for commercial use where weight was not a major consideration, they were not suitable for jet engines. The centrifugal compressor for the Whittle engine, the first British jet engine, was developed by trial and error with numerous modifications of the hub-shroud profile. The centrifugal compressor section of the National Advisory Committee for Aeronautics (NACA) designed, built and tested three compressor impellers during and after World War Il. They were part of a program designed to evaluate various blade shapes, but encountered such instabilities at the design pressure ratios that the experimental results led to no definitive conclusions. In 1948 the Centrifugal Compressor Section was given the assignment to further investigate the three impellers. The investigation led to the development of a quasi three dimensional design procedure that eliminated the guesswork from the basic design of a centrifugal impeller. Since the 1948 to 1955 time period over which the procedure was developed, the advances in computers have allowed refinements in the original computational methods. It is the objective of this presentation to review the history of the NACA centrifugal compressor program and efforts that have led to the latest developments in computational design procedures.