Case 1 discussion and conclusions
Comparison between measured velocities from the prototype and velocities
from the distorted models scaled up to prototype for Case 1 indicated that major
flow patterns and velocity vectors were in good similitude. Differences between
measured velocity vectors could be ascribed to small perturbations in the
steadiness of the flow, to small errors in the location of the measurement, or to
variations of the velocity offset measured by the LDV apparatus over the course
of the measurements. In addition, it was seen that small errors in the geometry
care was taken to align the boundaries carefully for each experiment.
Results measured in the Case 1 tests indicated that there were no substantial
differences between geometrically undistorted and distorted physical flow
models when the flow turbulence was manifested primarily in the horizontal
plane with only weak vertical turbulent fluctuations. The observation conforms
with the theoretical analysis given in Chapter 4.
Case 2: Flow Separation at Vertical Edge
The Case 2 experiments were virtually identical to the Case 1 free jet tests,
with the only difference being the two parallel boundaries downstream of the gap
that served to constrain jet expansion as shown in Figure 18(b). The pair of
jetties parallel to the principal flow direction extended for one-half the gap width,
and the ratio of gap width to jetty length was maintained in the distorted model
As in Case 1, measurements were first made using a configuration that was
assumed to be the prototype. Subsequent experiments used geometrically
distorted versions of the prototype as illustrated by the sketch in Figure 19.
Scaling factors for each test in the series along with relevant values for discharge
and key horizontal (Xp , Xm) and vertical (Zp , Zm) dimensions were the same as
Case 1 and are listed in Table 5. The planform layout of the experiment on the
flow table is sketched in Figure 29, and the measurement area had a width equal
to the gap width and length extending two-thirds of the gap width downstream
past the end of the jetties.
The prototype case and scaled models of the prototype having distortions
ratios (NX /NZ) equal to 2, 4, and 6, were tested for three different flow rates
(Q = 1.5 L/sec, 1.0 L/sec, and 0.75 L/sec). This gave a total of 12 experiments,
as detailed in Table 5. The elevation of the LDV measurement volume above the
bottom, and the horizontal measurement grid spacing (∆x, ∆y) for each
experiment was the same as listed in Table 6 for the Case 1 tests.
Chapter 5 Turbulence Scale Effects Experiments