Handbook of Turbomachinery Second Edition Revised - Ventech!

Figure 5 Design goals and their dependence on application.
engines, cost, performance, durability (expressed in mission life cycles),
weight, and engine noise levels are important items to be considered. For
military applications, the important items are performance and weight. The
regions with medium-dark shading are of intermediate importance, while
regions with dark shading indicate items of little concern. As seen from the
diagram, cost is of great concern in most applications. In military
applications, cost and long life are sometimes not as important as the
achievement of very high levels of performance.
Since APUs have relatively small outputs and are not in continuous
use, performance may not be a major consideration in their design. In all
other engines, performance plays an important role. The main factors
affecting performance are (1) thermodynamic cycle (maximum operating
pressure, turbine inlet temperature, and ambient conditions), (2) aerodynamic
efficiencies of the compressor and turbine vanes and blades
(depend on airfoil loads, flow path losses, etc.), (3) losses in the combustor
due to incomplete combustion, (4) losses due to installation effects, tip
clearances, etc., (5) losses due to secondary flow, and (6) thermal energy
losses from the turbine case to the surroundings. Of these, thermal losses are
not highly significant, so that the engine is treated as an adiabatic device in
most calculations.
Copyright © 2003 Marcel Dekker, Inc.