WÄRTSILÄ WARTSILA32, Руководство по эксплуатации продукта, Страница: 156 / 254

Fig 10-5 Example scheme of air and exhaust waste gate arrangement
In addition to limiting the cylinder peak firing pressure, the waste gates are also used to ensure
correct compressor performance. In cold conditions, the compressor can run in an area of
unstable delivery, which occurs at high pressure versus flow ratios. In such operation conditions
a stall occurs at some locations in the compressor due to a high degree of flow separation.
This compressor “surge” means a temporary interruption in the air flow and can be recognized
as a sound bang.
To reliably operate in all conditions, the actual operating line of the compressor needs a
sufficient margin to the “surge line”. The charge air pressure can be reduced with the waste
gates and thus moving the compressor operating point away from the “surge line”.
10.2.3.2 Suction air piping
If the engine is not designed for arctic operation and suction air temperature is below +5°C,
then a flap in the air duct is recommended. The flap is e.g. pneumatically operated. It can be
either opened or closed. In closed position, the suction air to the engine is taken from the
outside air. In open position, the suction air to the engine is taken from the engine room. The
flap is used during engine startup.
The suction air piping must be equipped with a filter, weather louver and a water trap. A
filter-silencer must be installed also to the flap engine room air intake connection. It is
recommended that the suction air piping is insulated to prevent excessive water condensation
to the pipe surface. The suction air piping arrangement is shown in 10-2.
10-6 Wärtsilä 32 Product Guide - a21 - 7 September 2016
Wärtsilä 32 Product Guide 10. Combustion Air System