Glossary
to accompany
Thermodynamics: An Engineering Approach, 5th edition
by Yunus A. Çengel and Michael A. Boles52Turbine inlet temperature (turbine firing temperature) is the temperature of the
working fluid at the turbine inlet. Increasing the turbine inlet temperature has been the
primary approach taken to improve gas-turbine efficiency. These increases have been
made possible by the development of new materials and the innovative cooling
techniques for the critical components such as coating the turbine blades with ceramic
layers and cooling the blades with the discharge air from the compressor or injected
steam.
Turbofan (or fan-jet) engine is the most widely used engine in aircraft propulsion. In
this engine a large fan driven by the turbine forces a considerable amount of air through a
duct (cowl) surrounding the engine. The fan exhaust leaves the duct at a higher velocity,
enhancing the total thrust of the engine significantly. A turbofan engine is based on the
principle that for the same power, a large volume of slower-moving air will produce more
thrust than a small volume of fast-moving air. The first commercial turbofan engine was
successfully tested in 1955.
Turboprop engine uses propellers powered by the aircraft turbine to produce the aircraft
propulsive power.
Turning angle (deflection angle) is the angle at which straight oblique shocks are
deflected as flow comes upon a body, like that produced when a uniform supersonic flow
impinges on a slender, two-dimensional wedge.
Two-stroke engines execute the entire cycle in just two strokes: the power stroke and the
compression stroke.
Uniform implies no change with location over a specified region.
Uniform-flow process involves the following idealization: The fluid flow at any inlet or
exit is uniform and steady, and thus the fluid properties do not change with time or
position over the cross section of an inlet or exit. If they do change with time, the fluid
properties are averaged and treated as constants for the entire process.
Units are the arbitrary magnitudes assigned to the dimensions.
Unity conversion ratios are ratios of units that are based on the definitions of the units in
question that are identically equal to 1, are unitless, and can be inserted into any
calculation to properly convert units.
Universal gas constant Ru is the same for all substances and its value is 8.314 kJ/kmol·K
and 1.986 Btu/lbmol·R.