AE 401-- Procedure -- Lab: Nozzle Performance - Clarkson University

AE 401 – Spring 2005
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2.0mm
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10 O
Thrust Force [ N ]
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
Calibration Data
y = 0.044185x - 0.033807
-0.5
0 10 20 30 40 50 60 70 80 90 100
Micrometer Reading
Figure 1: Nozzle Geometries
Figure 3: Micrometer calibration curve.
A rotameter is used to measure the mass flow
rate, ṁ, through the nozzle. The scale on the rotameter
is incremented in millimeters. The calibration
curve is used to convert from millimeters to the
mass flow rate. The calibration curve is shown in
Figure 4. Make sure you apply the density correction
factor k that can be obtained from Figure 5 or
Equation 17.
9
8
Calibration Data
y = 0.8895 + 0.0292x + 2.34e-5x 2
7
Figure 2: Apparatus for Nozzle Tests
Instrumentation
The thrust force is measured using what is effectively
a beam type load cell. The nozzle is threaded
into the end of a long section of tubing. The thrust
force produced as a result of mass being thrown
from the nozzle, causes the beam to deflect downward.
From our strengths of materials studies, we
know that a cantilever beam with concentrated load
can be described as:
y = F l3
3EI
(16)
The modulus of elasticity, E, the length of the
beam, l, and the moment of inertia, I, are all
constant which indicates that the deflection of the
beam, y should vary linearly with the thrust force,
F . Figure 3 demonstrates this and provides an
equation relating the displacement to thrust force.
Air Flow Rate / 10 - 3 kg ⋅ s - 1
6
5
4
3
2
1
0
0 20 40 60 80 100 120 140 160 180 200 220 240
Scale [ mm ]
Figure 4: Calibration curve for 35E rotameter with
duralumin float. Note: Curve is correct for ρ =
1.2kg · m −2 . Multiply mass flow rate by correction
factor, k, from Figure 5.
The rotameter calibration correction factor, k,
can be extracted from Figure 5. To obtain a reasonable
estimate of the correction factor from the plot,
the atmospheric pressure, P a and ambient temperature,
T , must be measured. The atmospheric pressure
can be measured using the mercury barometer
located on the wall near the safety goggle cabinet.
4