The efficient performance of a compressor or pump over a desired stall-free operating range is related to the fluid mechanic loading on the rotating and stationary blades. This loading is a function of the suction and pressure surface velocities and is commonly referred to as aerodynamic (compressors) or hydraulic (pumps) loading. Overall values of maximum limits have been established in design practice as a result of development work. However, the distribution of loading has not been well established. One source of guidance is the database provided by cascade data. Velocity distributions are available, and from this data, blade loading coefficients can be calculated with the intent of applying the results to blade design. In this paper, the blade loading equation is derived to illustrate the principal factors that influence blade loading. These factors include blade number, blade wrap angle, blade length, and the magnitude of the average velocity between blades as determined by flow path contours and blade thickness. The equation gives the designer the ability to make design adjustments to achieve proper loading distribution within recommended values of maximum loading. The review of the cascade data provides the designer with a reference for allowable design distribution and maximum loading limits.

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