58962 - Preliminary Design Tool for Centrifugal Compressors 

Centrifugal compressors increase the total pressure of a working fluid through the transfer of energy from rotating components. Compressors are frequently used in industrial and aerospace applications, and are designed on a stage-by-stage basis. Commonly, compressor designs rely on previous designs that can be modified slightly to achieve new operating requirements. In some cases, however, a completely new design is needed because no previous designs are available for the specific operating range of interest. Without a previous design, it is difficult to determine the appropriate impeller diameter, speed, number of compression stages, and blade design to achieve a successful design. While new compressor designs are a common occurrence in applied research applications, there is no defined method or tool available that helps bound the design parameters for a centrifugal compressor stage. Instead, tools are available that can be used to optimize the compressor design parameters for a specific goal. In this work, common practices to design centrifugal compressors were compiled to develop an Excel spreadsheet tool for quick estimation of the preliminary design parameters required to meet the desired compressor performance.

Centrifugal Compressors (Aungier), Introduction to Turbomachinery (Japiske), Turbomachines (Baljé) and other sources including experiment-based correlations were referenced to derive system performance characteristics and to select results based on best practices. The sheet functions from a series of assumptions based in these experiments and industry rules of thumb as well as performance parameters and initial flow conditions.  Performance inputs are specifications regarding the desired power input, fluid mass flow rate or volumetric flow rate, and total-to-total pressure ratio desired.  Initial conditions are specifications regarding the fluid flow, which include inlet total pressure, inlet total temperature, specific gas constant, ratio of specific heats, inlet swirl angle, fluid compressibility factor, and static density. All calculations assume the fluid to be an ideal gas.