1
00:00:10,713 --> 00:00:17,538
Hello, in this four-minute video
we are going to see how Heliciel

2
00:00:17,538 --> 00:00:24,154
simulates in CFD the same aircraft
propeller in its two lives:

3
00:00:24,154 --> 00:00:31,189
in cruise, and at static thrust,
with the aircraft standing still.

4
00:00:32,256 --> 00:00:40,957
Here is an aircraft propeller
1.8 metres in diameter with 7 blades,

5
00:00:40,957 --> 00:00:46,995
designed for a cruise at
56 metres per second,

6
00:00:46,995 --> 00:00:53,164
that is 202 kilometres
per hour, at 1,000 rpm.

7
00:00:53,214 --> 00:01:01,148
In cruise, the designer calculates
1,186 newtons of traction; at static
thrust,

8
00:01:01,148 --> 00:01:04,503
with the aircraft standing still,

9
00:01:04,503 --> 00:01:09,484
it announces 1,105 newtons,
for a higher torque.

10
00:01:11,645 --> 00:01:16,016
In cruise, the flow lines cross
the propeller almost straight:

11
00:01:16,016 --> 00:01:17,778
the aircraft moves fast,

12
00:01:17,778 --> 00:01:22,361
and the propeller adds only a few
metres per second to the wind.

13
00:01:22,411 --> 00:01:26,985
On the blades, the pressure
gathers along the leading edges.

14
00:01:27,035 --> 00:01:34,268
In the vertical plane, the 56 metres
per second wind fills the whole domain:

15
00:01:34,268 --> 00:01:42,263
the jet of the blades is lost in the wind,
and only the wake of the hub stands out.

16
00:01:42,313 --> 00:01:47,635
Across the axis, the imprint of the
seven blades can just be made out.

17
00:01:47,685 --> 00:01:54,517
With this Level 5 mesh, the bench
finds 794 newtons of traction,

18
00:01:54,517 --> 00:01:57,827
33 percent below the designer,

19
00:01:57,827 --> 00:02:02,251
for 66 kilowatts on the shaft; as always,

20
00:02:02,251 --> 00:02:07,969
this gap is to be looked
for first on the mesh side.

21
00:02:10,067 --> 00:02:16,406
Same propeller, same speed of
rotation, aircraft standing still:

22
00:02:16,406 --> 00:02:20,666
this time the air arrives from everywhere,

23
00:02:20,666 --> 00:02:27,069
from the side and from behind,
and leaves in a concentrated jet.

24
00:02:27,069 --> 00:02:30,671
No other method gives this picture.

25
00:02:30,721 --> 00:02:36,473
The cut shows that the useful jet
is a ring, not a full cylinder:

26
00:02:36,473 --> 00:02:41,341
behind the hub, a wide zone
of air stays almost still.

27
00:02:41,391 --> 00:02:46,756
Across the axis, each of the seven blades
prints its own trace in the projected air.

28
00:02:46,806 --> 00:02:50,424
With this Level 3 mesh, the first phase,

29
00:02:50,424 --> 00:02:57,570
where the propeller is frozen and the
rotation simulated, gives 1,020 newtons.

30
00:02:59,709 --> 00:03:03,870
But at static thrust nothing
comes from upstream:

31
00:03:03,870 --> 00:03:07,522
the propeller must really be made to turn.

32
00:03:07,572 --> 00:03:13,776
The second phase gives 820 newtons of
traction, and that is the value to keep.

33
00:03:13,826 --> 00:03:20,750
It also gives the rhythm of the
propeller: 116.7 hertz of blade passing.

34
00:03:23,107 --> 00:03:25,931
With Heliciel, one propeller is checked in

35
00:03:25,931 --> 00:03:29,023
cruise and at take-off
with the same buttons.

36
00:03:29,073 --> 00:03:34,301
We could now look for the best
compromise of pitch between the two.