DAVIS. — A m PLANE FOR THERMODYNAMIC CYCLIC ANALYSIS. 637 



curve of the family for which T^ = 2\ coiucides with the P axis. All 



the curves end in the line 7-* = 1. 



The velocity curves are in Figure 4. Any velocity greater than zero 

 -is possible, but here P, as well as Q, must be taken sufficiently small. 

 ' All the V curves start from finite points on the P axis but run off 



asymptotically to the line P = 1. The velocities in the central parts 



of the figure are of the same order as those obtainable with steam. 



450 500 



Qin BTU 



Figure 4. 



TtjjK A. Velocity. Showing, for Braj-ton cycles, the velocity in feet per second 

 of the stream of gas as it strikes the blades of the turbine. 



In the problem proposed, upper limits were assigned both to T^ and 

 to F", and we have called these limits T^ and V. That is, speaking 

 graphically, no cycle is available whose point lies beyond either of the 

 curves T^ = 7\ or V = V, and the remote parts of the P Q plane are 

 to be left out of consideration. There remains a finite portion of the 

 plane (the shaded area of Figure 5*) within which an available cycle must 

 lie. It may be called the V 1\ area, or, less explicitly, a. V T area. 



* The limits represented in Figure 5 are t^ = 400° F. (that is fe = 861° F. 

 Abs.) and V= 4000 ft. per sec. 



