UNSTEADY SIMULATION OF A TWO-STAGE COOLED HIGH PRESSURE TURBINE USING AN EFFICIENT NON-LINEAR HARMONIC BALANCE METHOD
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The harmonic balance method is a mixed time domain and
frequency domain approach for efficiently solving periodic unsteady
flows. The implementation described in this paper is designed
to efficiently handle the multiple frequencies that arise
within a multistage turbomachine due to differing blade counts
in each blade row. We present two alternative algorithms that
can be used to determine which unique set of frequencies to consider
in each blade row. The first, an all blade row algorithm,
retains the complete set of frequencies produced by a given blade
row’s interaction with all other blade rows. The second, a nearest
neighbor algorithm, retains only the dominant frequencies in
a given blade row that arise from direct interaction with the adjacent
rows. A comparison of results from a multiple blade row
simulation based on these two approaches is presented. We will
demonstrate that unsteady blade row interactions are accurately
captured with the reduced frequency set of the nearest neighbor
algorithm, and at a lower computational cost compared to the
all blade row algorithm.
An unsteady simulation of a two-stage, cooled, high pressure
turbine cascade is achieved using the present harmonic balance
method and the nearest neighbor algorithm. The unsteady results
obtained are compared to steady simulation results to demonstrate
the value of performing an unsteady analysis. Considering
an unsteady flow through a single blade row turbine blade passage,
it is further shown that unsteady effects are important even
if the objective is to obtain accurate time-averaged integrated
values, such as efficiency.

Author Name: 
Chad H. Custer
Jonathan M. Weiss
Venkataramanan Subramanian
Kenneth C. Hall
Author Company: 
CD-adapco
Department of Mechanical Engineering and Materials Science, Duke University
Products: 
Conference Location: 
San Antonio
Conference Proceeding PDF: 
Conference Date: 
Monday, June 3, 2013
Conference Name: 
ASME Turbo