SAMPE Journal - March/April 2024 - 19

(a) SW-side view
(b) stagnation-top view
Figure 7. Comparison of the experimental wall pressure measurements to the numerical simulation for the (a) conical nozzle, for two mass flow
rates: 8 g/s (left) and 16 g/s (right), (b) semi-elliptical nozzle, for two mass flow rates: 8 g/s (left) and 12 g/s (right).
Wall pressure measurements: Similarly to
the conical nozzle, the semi-elliptical nozzle
is equipped with three pressure taps along the
diverging section shown in Figure 4. These are
compared with CFD in Figure 7b. The two first
pressure ports show values inside the 10% error,
but the last port is far off. We suspect this is due
to the extremely sensitive Validyne sensor used
malfunctioning and giving false readings. Further
investigation must be carried out to better justify
the root cause.
Flat plate heat flux: Characterizing the semielliptical
nozzle poses greater challenges compared
to the conical nozzle. Although a similar strategy
involving stagnation point pressure and heat
flux measurements could be employed, it may
not provide accurate information for the specific
location of interest, which is conducted in a flat plate
configuration. Therefore, it is essential to measure
the heat flux across the flat plate section to obtain
representative and relevant measurements. In pursuit
of this objective, an in-house designed and
built calorimeter has been constructed to measure
the heat flux across the flat plate. The calorimeter
is embedded within the flat plate configuration
as shown in Figure 6. The calorimeter is outfitted
with a total of five individual cells and six thermocouples.
A water line interconnects all cells in
series, and the thermocouples are employed to
measure the temperature of the water entering
and exiting each cell independently. Theoretically,
the heat flux profile can then be obtained by fitting
the temperature and calculating the corresponding
heat flux. Practically, this has shown to be
difficult, and therefore only the average heat flux
along the whole calorimeter is presented in Table 4.
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pw1
[ Pa ]
1600.2 (+0.8%)
2014.3 (+3.5%)
2290.5 (+0.8%)
2623.8 (-0.3%)
3386.2 (-1.3%)
3793.8 (-0.2%)
pw2
[ Pa ]
746.2 (-0.6%)
946.8 (+3.1%)
1076.8 (+1.4%)
1233.8 (+1.0%)
1594.6 (+1.1%)
1800.3 (+4.6%)
pw3
[ Pa ]
284.3 (-2.2%)
362.7 (+5.1%)
411.4 (+2.6%)
470.5 (+2.3%)
607.7 (+2.5%)
691.1 (-19.0%)
Table 2. Wall pressure values obtained numerically and comparison to experimental
values for the conical nozzle. From top to bottom: mass flow rate= 6, 8, 10, 12, 16, and
20 g/s.
.
m
p
res
[ g/s ] [ hPa ]
6
8
10
12
16
20
141.4
164.6
179.8
202.7
242.4
272.6
p
ch
[ hPa ]
2.60
3.06
3.67
4.47
6.44
8.97
p
stag
[ hPa ]
34.23 ± 3.53
41.65 ± 4.21
46.10 ± 4.64
50.83 ± 5.10
54.15 ± 5.43
59.01 ± 5.91
qw
[ MW/m2
]
3.407 ± 0.175
3.639 ± 0.176
3.469 ± 0.175
3.320 ± 0.176
1.646 ± 0.168
1.407 ± 0.167
Table 3. Evaluation of the stagnation point pressure and heat flux reached at d = 42.9
mm from the conical nozzle exit.
The heat flux is seen to increase drastically with
increasing angle of attack, and decrease with
increased mass flow at a constant power setting.
Unfortunately, the pressure measurements for the
flat plate configuration across the flat plate were
not conducted as the equipment was not available
at the time and it is part of the future work.
MARCH APRIL 2024
|
SAMPE JOURNAL |
19
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SAMPE Journal - March/April 2024

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