Handbook of Turbomachinery Second Edition Revised - Ventech!

Corrections for Streamline Curvature
Hamrick et al. [29] reports an early attack on this problem, which is very
important in centrifugal compressors. The position of the projected
streamlines is assumed; the radial pressure gradients induced by the
curvature of the streamlines and the rotation of the gas are then calculated.
The resulting changes in the velocities and gas densities are evaluated. One
then revises the positions of the streamlines as required by flow continuity.
This of course changes the curvature of the streamlines, so the previous
calculations are repeated and the radial pressure gradients are corrected.
This iterative process is continued until satisfactory agreements are reached.
Novak and Hearsey [30] improves this concept and shows how it can be
extended to axial-flow compressor design.
Combination of Separate Two-Dimensional Flow Calculations
Simultaneous equations of flow on two surfaces, designated as S1 and S2, are formed from the three-dimensional equations for inviscid flow. These
surfaces are more or less orthogonal to each other. The resulting equations
are used to determine ideal gas velocities throughout a blade row.
This procedure allows the effects of entropy gradients to be
considered, but not the local effects of viscous action. Entropy gradients
are initially assumed, and the velocities are calculated. These velocities,
together with boundary-layer theory, shock loss calculations, and blockage
estimates, are used to reevaluate the entropy gradients. The calculations are
reiterated as often as required in order to establish a consistent distribution
of velocities and losses.
This concept was originated in 1952 by Chung Hua Wu and has been
continuously developed by him over the intervening period. Wu et al. [31]
and Wu et al. [32] demonstrate the usefulness of this approach and provide
an extensive list of supporting references. This method is often preferred to
other inviscid calculations.
Use of Three-Dimensional Inviscid Flow Theory
Finite-difference or finite-element forms of the inviscid equations of flow in
three dimensions are written. Corrections for boundary layers on the blades
and on the inner and outer walls are made as indicated in the preceding two
methods. Katsanis and McNally [33] presents a typical procedure that can
use this concept.
Copyright © 2003 Marcel Dekker, Inc.