The detailed aerodynamic design of centrifugal compressor stage components relies heavily on the use of internal flow analysis methods, such as the quasi-three-dimensional flow analysis method presented in Chapter 12 and the blade-to-blade flow analyses of Chapters 13 and 14. These so-called Euler methods neglect the effects of viscosity in the interest of obtaining the computational speed and fast response a designer needs for the iterative process of establishing the annulus wall contours and blade geometry. These inviscid flow analyses provide valuable guidance to the designer in the form of blade loading distributions and velocity or pressure distributions along the gas path boundaries. But the omission of the important viscous effects means that the designer’s skill and experience in the interpretation of the results is critical to success. Experienced designers develop very definite opinions as to blade loading styles that will be effective and to levels of adverse pressure gradients that can be tolerated. In effect, they apply judgment as to how viscous effects will modify the inviscid flow analyses they use for detailed design.