# Glossary

### Bypass Ratio

Defined as the ratio of the mass flow going through the outer bypass divided by the mass flow going through its core. ### Euler’s Turbomachinery Equation ### Flow Coefficient ### Degree of Reaction ### DeHaller Number  ### Diffusion Factor ### h-s (Mollier) Diagram

Similar to a T-s diagram, is a plot of enthalpy (j/Kg) vs. entropy (j/KgK). Lines of constant pressure are plotted. Radial equilibrium signifies no radial velocity component at entry and exit of blade row (Cr=0). Any radial flow is within blade row; outside the row, flow is in radial equilibrium, as demonstrated by Figure 1, below. For more on Radial Equilibrium, go here. ### Solidity

A measure of the ‘fullness’ of a blade row. ### Total to Total Stage Efficiency ### Velocity Triangle

A 2-D representation of the velocity distribution at a radial slice of a blade. Usually displaying axial and radial components of absolute and rotational velocity. • Compressor
• Turbine
• Counter-Rotating

### Work Coefficient 