Environmental Engineering Reference
In-Depth Information
Aligned
Staggered
(a)
(b)
(c)
(d)
t = 400 sec
Fig. 8.21
Ice residue for different layouts at t = 400 s after switching on the resistors with an
q = 400 W/m
2
.
V
ice
¼
7
:
64
10
5
m
3
.
input
heat
flux
of
a
Aligned
square
layout
with
m
3
.
V
ice
¼
8
:
72
10
5
b
Staggered
square
layout
with
c
Aligned
circular
layout
with
m
3
. d Staggered circular layout with V
ice
¼
5
:
58
10
5
m
3
V
ice
¼
4
:
97
10
5
de-icing times t
di
of less than 800 s assuming that there is no convection loss on
the blade surface. Adding equal forced convection loss does not change the out-
come of layout performance comparison. Furthermore, the ANSYS simulation
results show that the de-icing times t
di
for aligned square and staggered square
layouts are 1,350 and 1,116 s, respectively. Although the staggered square layout
melts the ice layer faster than the aligned square layout, it is not capable of
removing ice from the leading edge area for a long time. Therefore, the aligned
square layout is preferable to the staggered square layout for localized active de-
icing because it removes the ice first from the leading edge area.
The values of the performance cost function J based on Eq. (
8.4
) for different
heater layouts and geometries are shown in Table
8.2
. These results show that
staggered circular heaters achieve the best performance with 40 % faster de-icing
and 39.3 % smaller maximum blade temperature compared to aligned square
heaters. Furthermore, V
T[30
is reduced from 6.5 % to 0.5 % of the blade volume
using staggered circular heaters compared to aligned square heaters. Comparing
aligned circular heaters to aligned square heaters shows 39.8 % faster de-icing,
29.5 % reduction in T
max
b
, and reduction of V
T[30
from 6.5 % to 1.15 % of the
blade volume for aligned circular heaters. Other polygon heaters (pentagonal and
