Fig 10-2 Engine room ventilation, air duct connected to the turbocharger
(DAAE092652A)
10.2 Combustion air system design
Usually, the combustion air is taken from the engine room through a filter on the turbocharger.
This reduces the risk for too low temperatures and contamination of the combustion air. It is
important that the combustion air is free from sea water, dust, fumes, etc.
For the required amount of combustion air, see section Technical data.
The combustion air shall be supplied by separate combustion air fans, with a capacity slightly
higher than the maximum air consumption. The combustion air mass flow stated in technical
data is defined for an ambient air temperature of 25°C. Calculate with an air density
corresponding to 30°C or more when translating the mass flow into volume flow. The expression
below can be used to calculate the volume flow.
where:
combustion air volume flow [m³/s]q
c
=
combustion air mass flow [kg/s]m' =
air density 1.15 kg/m³ρ =
The fans should preferably have two-speed electric motors (or variable speed) for enhanced
flexibility. In addition to manual control, the fan speed can be controlled by engine load.
In multi-engine installations each main engine should preferably have its own combustion air
fan. Thus the air flow can be adapted to the number of engines in operation.
The combustion air should be delivered through a dedicated duct close to the turbocharger,
directed towards the turbocharger air intake. The outlet of the duct should be equipped with
Wärtsilä 46F Product Guide - a19 - 1 December 2017 10-3
10. Combustion Air SystemWärtsilä 46F Product Guide
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