SuperFlow AutoDyn, Руководство оператора, Страница: 36 / 208

M a n u a l
AutoDyn
Section 4 - Page 10
AutoDyn manual Section 4. PM7, 5/2004
Air Flow Velocity vs Test Pressure
inH2O Pa Ft/s mph km/h
0 0 0 0 0
1 249 66 45.1 72.2
2 498 94 63.8 102.1
3 747 115 78.2 125.1
4 996 132 90.3 144.4
5 1246 148 100.9 161.5
6 1495 162 110.6 176.9
7 1744 175 119.4 191.1
8 1993 187 127.7 204.3
9 2242 199 135.4 216.7
10 2491 209 142.7 228.4
11 2740 220 149.7 239.5
12 2989 229 156.4 250.2
13 3238 239 162.7 260.4
14 3487 248 168.9 270.2
15 3737 256 174.8 279.7
16 3986 265 180.5 288.9
17 4235 273 186.1 297.8
18 4484 281 191.5 306.4
19 4733 289 196.7 314.8
20 4982 296 201.9 323.0
Air Speed Air Pressure
Only centrifugal fans are capable of providing the pressures needed for
high speeds.
4.4.4. Exhaust extraction
In addition to noxious gases, a significant amount of heat is released
through the exhaust system. A proper exhaust extraction system is
critical for the safety of your employees inside and outside the test
room.
The exhaust system should be able to handle both the flow and the
temperature of the exhaust gas. Most ventilation ducts and fans only
handle temperatures up to 250 degF (110 degC). It is easier to design a
system for higher flows than one for higher temperatures, so exhaust
gas is generally diluted with ambient air. For best results, the dilution
ratio should be somewhere between 2 and 4.
As with spot cooling fans, the exhaust fan is usually a high-speed fan
of the centrifugal type. Proper temperature-resistant ducting should be
installed to capture the exhaust gas close to the vehicle tailpipe. Do not
seal the duct to the tailpipe: this would prevent dilution of the exhaust
gas with ambient air and would also influence engine performance by
reducing the exhaust back-pressure. There should be enough free area