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Handbook of Turbomachinery Second Edition Revised - Ventech!

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Figure 10 (a) Deflection <strong>of</strong> flow <strong>of</strong>f pressure surface at blade end and through tipclearance<br />

region to roll-up as vortex near suction surface, (b) displacement <strong>of</strong><br />

passage vortex by tip-clearance vortex.<br />

be tolerated there is limited. Moreover, the retarded flow occupies space and<br />

reduces the effective flow area.<br />

One must acknowledge that classic methods <strong>of</strong> calculating boundary<br />

layers (e.g., McDonald [8]) do not include the realities <strong>of</strong> secondary flows.<br />

This fact has stimulated much <strong>of</strong> the efforts for devising numerical<br />

techniques capable <strong>of</strong> estimating three-dimensional viscous flow phenomena.<br />

CHOKED FLOW AND SHOCK WAVES<br />

Special considerations are necessary when the relative flow ahead <strong>of</strong> a blade<br />

row approaches or exceeds the speed <strong>of</strong> sound. Here again we must<br />

Copyright © 2003 Marcel Dekker, Inc.

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