Page 45 - Winter Issue 2018
P. 45

V, _ A " r . _ _.-. ._;v_ g.;..~_ (ejt: 5.75 «.1
la) I—0.6>  . l J7,‘ . ,  _.. _ _ A1 , I i Q ,
7,:  " l
:2 ; '1 5  _  xi:  o 
- - hr  “‘ l ‘I  ~"  l "= A ‘ 
—- ,—_ ‘ ‘—:.  ’ :~. 1 \«.;.1‘
‘T  -tr 4 -  '1 ‘° ‘ '  . l "pl
(1)) 1:1 .73  ,; --‘_;_.- .— ;‘M“;, .  1f,lt~ 6.l§  | E
" i ' l 1 .. ii
3; 4 I .. -
T 3;  u  1, . _ *   , :5 
g _,___’ 1 ..:- ~ ., ‘  M ... . .. -_,x\ ‘ .. .1
. . ' rdV=xflf}-. ‘ ‘'4 I‘  u L ‘s 4 ,  V l ’ f,i;- 
—q .-—. _ 17’ _— if‘ ,1 y . .  ~
.-I 3'3 sf ~- .' "§'—" 7°‘ if  _ 1 ' 
_ , 1
_ ..  ' , ‘ , 1 » Q ‘
(«i)I’2.9s ‘I? H, x -. ~~ .i ‘*3 ' 7; _ 19-‘T’ 7-'5 l:« g y
j 4 ' ‘ I 5 1 .
 G I "  3
21,.‘ 1-, — .,j' '1; | .n '1.
, c .. ' - «o ‘ ' -' . .  .7:-:.—~
r,,._.. 3* ~ , 1,. — .-  1   vlzs.---»
—   (‘I ' v» '1  N }/—‘'7°
-  —_ r I — ‘ 1 l  ‘ g . V W.
((_lll=4.5$ 1:,  V lhl[:8‘7S  l ,
~ - ~  I |
" l .. — I I
 y |
' -'  . *: ;j; ‘t' .. v_     I
Q‘ . , ‘ r)'::_.£,.,Ll ‘J. _ __ .  l . -§f=f‘l:,_,§
‘ V 1 '- - ' " . -n. J ,‘ -. 3
' i ' -,. l ‘ . r ‘ ’ .l
.» l '1 _~ ‘' ‘ ' ‘
Figure 5. Left, a—h: noise maps superimposed on frames from an infrared camera, conventional beamform at 2 kHz; right: corresponding
frames from a high—speed camera. Reproduced from Panda et al. (2013, Figure 11). See text for further explanation.
obvious difficulties in full-scale experiments, launch ve- tic temperature has been measured in a rocket noise field
hicle design is heavily reliant on scale-model testing, where and found to contribute significantly to the total tempera-
the results can prove invaluable (Bies and Franken, 1961). ture variations (Giraud et al., 2010). Near-field vector inten-
A recent comparison between full-scale and model-scale sity measurements on a model rocket motor indicate that
data shows good correlation, indicating that scale data can as the frequency increases, the dominant source region
be used with confidence (Giacomoni and Kenny, 2016). In- contracts and moves upstream, with peak directivity occur-
deed, a source localization and reconstruction technique has ring at greater angles from the plume axis (Gee et al., 2010).
lately been employed to successfully analyze wall pressure The noise source, conventionally assumed to be the rocket
measurements on a model launch vehicle (Casalino et al., plume, is known to be directional and distributed and can
2012). Similarly, aerovibroacoustic methods are currently be modeled by line arrays of monopoles that mimic the par-
being developed for predicting the response of a rocket to tially coherent nature of jet noise (Morgan et al., 2012). Re-
the intense acoustic environment inside the nose cone used cent work has shown that including source correlation and
to protect the payload (Tsutsumi et al., 2016). Such research atmospheric turbulence in the model improves the predic-
is of great importance in rocket design. tions (Gee et al., 2014).
Recent efforts have also focused on collecting acoustic data The first beamforming experiment conducted during an
from static-fire rocket tests in an attempt to characterize actual launch, in which microphones were placed on the
the full-scale rocket plume noise environment. The acous- rocket itself, confirmed the source distribution found dur-
Winter 2018 | Acnuseica Thclay | 43













































   43   44   45   46   47