Figure
5. Comparison of contours of the dimensionless time-averaged (a, b)
axial and (c, d) radial velocities between (a, c) LES predictions and
(b, d) experimental results on the plane of P45.
To further evaluate the prediction accuracy, two radial positions on the
plane of P45, i.e. r /R = 0.7 and 0.9, are
taken out for quantitative comparison. The profiles of the dimensionless
time-averaged velocities and velocity fluctuations (in terms of RMS
velocities), are shown in Figures 6 and 7, respectively. Here, the
time-averaged velocities and velocity fluctuations are all normalized by
the tip velocity of the composite blade, U tip.
Obviously, the predicted time-averaged radial and axial velocities are
almost identical with the experimental results. However, there is a
slight difference between the predictions and the experimental results
for the velocity fluctuations, although the profile distribution
patterns are very similar. The velocity fluctuations are over-predicted
with a mean error of about 25%.