TABLE OF CONTENTS From the Euler equation in the form of equation 5.10, it was argued that the temperature ratio across a stage should depend on the tangential Mach number of the rotor M T, on the axial flow Mach number M b (or M a), and on the flow geometry as controlled by the blade angles, so we should be able to correlate, say, ? s as a function of M T and M a. To obtain the pressure ratio, the efficiency must be introduced; however, if ? s is a function only of M T, M a, and flow geometry, then ? s = ? s( M a, M T). In practice, stage performance can be correlated in this way as long as the Reynolds number is sufficiently large (greater than about 3 10 5 based on blade chord).
A different set of parameters is preferred, although they are equivalent to M a and M T. They are the corrected speed, defined as
and the corrected weight flow, defined as
where T r and P r are the sea-level standard atmospheric pressure and temperature, 2116.2 lb/ft 2 and 519 R. That N/ ? ? is equivalent to M T for a given tip diameter is obvious. By expressing W, ? and ? in terms of the axial Mach number and stagnation conditions,...
