Handbook of Turbomachinery Second Edition Revised - Ventech!

Lastly, although pump isentropic efficiency is seldom an issue for the
‘‘open-cycle’’ rocket engine systems, efficiency thresholds are often
introduced by the expander and staged combustion cycle systems. In this
case, the pump must demonstrate an efficiency in excess of the threshold
value if design chamber pressure is to be achieved. Contemporary
centrifugal pumps have repeatedly shown themselves to be capable of
meeting these efficiency requirements without major difficulty.
In our previous discussions, we have described the engine balance
from which the interface conditions and performance requirements for the
propellant pump can be derived. In addition, when a liquid rocket engine
system is designed, a maximum weight specification for the system typically
exists. This allowable weight is divided between the system’s components,
and a ‘‘weight bogie’’ for each component is derived. For the propellant
pumps, this weight requirement is often the most challenging facet of the
pumps’s design.
The design process for a propellant pump consists of three essential
phases—conceptual design, preliminary design, and detailed design. The
conceptual design process for a propellant pump begins with the aid of Eq.
(1) and data such as depicted in Fig. 15(d). Using the required pump head
Figure 15d Typical impeller inlet showing blade leading edges and inlet vectors.
Copyright © 2003 Marcel Dekker, Inc.