Fluid Mechanics and Thermodynamics of Turbomachinery, 5e

Combined with p/r = RT the above expression gives, on eliminating p, r/T n = constant,
hence
(4.35)
where n = g /{hp(g - 1)} - 1.
For an infinitesimal temperature drop eqn. (4.33) combined with eqns. (4.34) and
(4.35) gives, with little error,
Integrating eqn. (4.36),
(4.36)
where K is an arbitrary constant.
To establish a value for K it is noted that if the turbine entry temperature is constant
Td = T 1 and T = T 1 also.
Thus, K = [1 + (m . /m . d) 2 ]T I 2n+1 and
(4.37)
Equation (4.37) can be rewritten in terms of pressure ratio since T/TI = (p/p I) h p (g-1)/g . As
2n + 1 = 2g /[hp(g - 1)] - 1, then
(4.38a)
With hp = 0.9 and g = 1.3 the pressure ratio index is about 1.8; thus the approximation
is often used
which is ellipse law of a multistage turbine.
The Wells turbine
Introduction
Axial-flow Turbines: Two-dimensional Theory 125
(4.38b)
Numerous methods for extracting energy from the motion of sea-waves have been
proposed and investigated since the late 1970s. The problem is in finding an efficient
and economical means of converting an oscillating flow of energy into a unidirectional
rotary motion for driving an electrical generator. A novel solution of this problem is
the Wells turbine (Wells 1976), a version of the axial-flow turbine. For countries sur-