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Handbook of Turbomachinery Second Edition Revised - Ventech!

Handbook of Turbomachinery Second Edition Revised - Ventech!

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temperature by forming a thin film over it. Geometric and flow parameters<br />

associated with the cooling mechanisms (internal and external) form part <strong>of</strong><br />

the design variables set for the optimization problem. The internal coolant<br />

passage has five sections, each spanning the blade span (root to tip). Each<br />

blade section has six film cooling holes connected to the appropriate sections<br />

<strong>of</strong> the internal coolant passage (Fig. 2). The set <strong>of</strong> design variables includes<br />

the locations <strong>of</strong> the Bezier control points, the positions <strong>of</strong> the center <strong>of</strong> each<br />

film-cooling hole, and the positions <strong>of</strong> the side boundaries <strong>of</strong> each internal<br />

coolant passage section. The surface boundary conditions are appropriately<br />

modified to account for film-cooling flow when evaluating the external flow<br />

field.<br />

Aerodynamic Analysis<br />

A three-dimensional, thin-layer Navier–Stokes solver (RVC3D) is used to<br />

evaluate the flow field around the blade [40, 41]. The computational grid for<br />

the flow solver is generated using the grid generator TCGRID [42]. The<br />

Navier–Stokes equations in the Cartesian coordinate system rotating with<br />

the angular velocity O about the x-axis are mapped to a general body-fitted<br />

ðx; Z; zÞ-coordinate system with the x-coordinate following the flow<br />

Figure 2 Blade model: 2D view <strong>of</strong> blade section with coolant paths.<br />

Copyright © 2003 Marcel Dekker, Inc.

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