1.2
Application Examples
1000
1500
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3500
4000
20
30
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50
60
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100
p
s
c
a
v
in
m
b
a
r
Engine load in %MCR
TCA55-21004V on 6S46MC-C
S pec ific ation T C A55-21004V, VT A c los ing
S pec ific ation T C A55-21004V, VT A open
S tandard s pec ific ation T C A55-20027 w ith fixed
noz z le ring
Max. allow able ps c av
S am e s pec ific ation as T C A55-21004V but w ith
fixed noz z le ring
A ux. B lo we r switch p o int
with V TA = 2 7 % L o a d
A ux. B lo we r switch p o int
without VTA = 3 2 % L o a d
p
scav
Scavenge air pressure
MCR Maximum Continuous Rating
Figure 2: Increased scavenge air pressure with TCA55-21V on 6S46MC-C TIER I
MAN 2-stroke diesel engine 6S46MC-C with TCA55-21V turbocharger
The diagram Increased scavenge air pressure with TCA55-21V on 6S46MC-
C illustrates the mode of operation of the VTA on the 6S46MC-C engine.
The upper green line shows the scavenge air pressure that is set when the
VTA is closed towards partial load (“VTA closing”). In contrast, the scavenge
air pressures for the VTA test specification TCA55-21004V with the nozzle
ring remaining open for partial load (“VTA open” –
▲
dark line, bottom) and
the initial specification TCA55-20027 with rigid nozzle ring are also shown (
■
light points).
Since, for this engine, no device is offered for varying the start of injection, an
increase in the ignition pressure at partial load can only be achieved by
means of the scavenge air pressure. If a specification with a smaller rigid
nozzle ring were to be selected, a reduction of the maximum available power
VTA on 2-stroke diesel
engine
1 Adjustable turbine nozzle ring (VTA)
1.2 Application Examples
2013-12-04 - de
1
MAN Diesel & Turbo
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