AMCA InMotion - September 2019 - 18

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velocities of 1,791 fpm (9.1 m/s) and 2,707 fpm (13.75

was that wind effect on air-curtain performance is more

m/s) at discharge angles of 0 degree and 20 degrees

pronounced when discharge velocity is excessively weak.

and four wind speeds between 197 and 787 fpm (1 and

For the sub-scale testing, a 1:10-ratio model of the

4 m/s) for 18 different inﬁltration rates (Figure 5). The

large-scale chamber was mounted in the wind tunnel on

resulting 288 tests mapped the different flow rates

a 360-degree turntable base to obtain different relative

vs. the corresponding pressure differences across the

wind angles. Multiple chambers and inserts were created

door. The results of the higher wind speeds (e.g., 591 and

within the model and ported to compressed-air supplies to

787 fpm [3 and 4 m/s]) showed air-curtain performance

provide building pressure, air-curtain discharge velocity,

can be affected by higher winds. The impacts, however,

and discharge angle. The ﬂows were controlled with digital

were shown to be minimal when discharge velocity and

ﬂow-rate meters and calibrated with hot-wire anemometers.

angle were set to ensure a good seal of the opening.

A PIV test setup with aluminum-oxide powder seeding,

Comparative tests for wind effect focused on varying

Nd:YAG laser outside the wind tunnel, and camera inside

wind speed and constant air-curtain airﬂow and building

the tunnel was used to record the ﬂow pattern of the air-

pressure. For a given discharge velocity and angle, an

curtain discharge-jet cross section (Figure 6).

increase in wind speed generated a change in both door air

The sub-scale air-curtain discharge velocities were

inﬁltration and pressure difference. In all, 168 compara-

adjusted to be within 5 percent of their large-scale coun-

tive tests were performed. An additional 168 tests using

terparts. Two hundred eighty-eight tests were conducted

a lower discharge-velocity speed of 1,102 fpm (5.6 m/s)

using 1,122- and 1,890-fpm (5.7 and 9.6 m/s) discharge

were conducted to investigate a relatively weaker air-

velocities, 0- and 20-degree discharge angles, and 0-, 787-,

curtain jet under different wind conditions. As expected,

and 1,969-fpm (0, 4, and 10 m/s) wind speeds at a 0-degree

increased wind speed resulted in increased pressure differ-

wind angle (straight at the door). To determine the impact

ential and inﬁltration rate across the opening (using a

of wind angles, an additional 144 tests were performed

1,102-fpm [5.6 m/s] discharge velocity and a 0-degree

using a model variation with and without doors for a base-

discharge angle). An important ﬁnding of the research

line setup of 787-fpm (4 m/s) wind speed, 1,890-fpm (9.6
m/s) discharge velocity, and 0-degree

0.2

Q (m 3/s

0.3
0° air curtain

discharge angle for wind angles of 0,

20° air curtain

30, 60, 90, and 120 degrees.
Generally, at high wind speeds
(e.g., 1,969 fpm [10 m/s]), air-curtain
performance was affected drasti-

0.1

cally, with inﬁltration breakthroughs

∆P (Pa)
0.0
-1

1

3

5

-0.1

-0.2

7

9

11

13

15

starting earlier and at lower pressure
17

differences than with no wind. When

Supply 1 wind 0 m/s
Supply 1 wind 3 m/s
Supply 1 wind 3.5 m/s
Supply 1 wind 4 m/s

the air-curtain jet was able to reach

Supply 2 wind 0 m/s
Supply 2 wind 3 m/s
Supply 2 wind 3.5 m/s
Supply 2 wind 4 m/s

787 fpm [4 m/s]) had almost zero

the ﬂoor and provide a good seal over
the door, however, a mild wind (e.g.,
impact on performance. This also
was shown in the sub-scale wind-

-0.3

speed-effect tests, in which a discharge

FIGURE 5. Air-curtain overall-performance comparison.

velocity of 1,890 fpm (9.6 m/s) at angles

18

20 19 A M CA i n m o t i o n

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AMCA InMotion - September 2019

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