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Handbook of Turbomachinery Second Edition Revised - Ventech!

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Figure 2 Typical turbine map.<br />

cracks, and seals, and leakage flow rates throughout the stage flow path can<br />

impact overall performance. Separate performance maps are normally<br />

required for each geometric configuration. Often performance scalars are<br />

defined to quantify stage performance differences due to small geometric<br />

variations.<br />

Normally, full-scale component test rigs are used to experimentally<br />

define performance maps. Meaningful performance measurements are made<br />

when actual flow paths, blading, and rotor speeds are faithfully reproduced.<br />

In addition, inlet and outlet velocities, pressures, and temperature<br />

distributions must also simulate accurately those in the gas turbine engine<br />

installation. Specialized hardware and instrumentation are also used to<br />

support design development and diagnostic testing.<br />

Operational Characteristics’ Impact on Performance<br />

It is important to recognize that specific performance numbers defined by<br />

component maps are dependent on several different stage operational<br />

characteristics. These include nonuniform inlet flows, commonly referred to<br />

as inlet distortion, Reynolds number effects, changes in gas thermodynamic<br />

properties, and transient operations. There is no generalized methodology to<br />

account for the impact <strong>of</strong> these characteristics on steady-state performance.<br />

For a given stage, different operational characteristics can result in different<br />

performance maps.<br />

Copyright © 2003 Marcel Dekker, Inc.

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