Unsteady flow structure: dual array of spherical and cylindrical dimples
Выполнена экспериментальная программа в Военно-воздушной академии США, направленная на изучение нестационарной структуры потока перед, внутри и за двойным рядом “мелких” (h/D = 0,1) сферических и цилиндрических углублений на плоской поверхности. Сравнение показало, что первый ряд углублений “подавля...
Збережено в:
| Дата: | 2007 |
|---|---|
| Автори: | , |
| Формат: | Стаття |
| Мова: | English |
| Опубліковано: |
Інститут технічної теплофізики НАН України
2007
|
| Назва видання: | Промышленная теплотехника |
| Теми: | |
| Онлайн доступ: | http://dspace.nbuv.gov.ua/handle/123456789/61213 |
| Теги: |
Додати тег
Немає тегів, Будьте першим, хто поставить тег для цього запису!
|
| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Цитувати: | Unsteady flow structure: dual array of spherical and cylindrical dimples / A. Khalatov, A. Byerley // Промышленная теплотехника. — 2007. — Т. 29, № 1. — С. 5-11. — Бібліогр.: 6 назв. — англ. |
Репозитарії
Digital Library of Periodicals of National Academy of Sciences of Ukraine| id |
irk-123456789-61213 |
|---|---|
| record_format |
dspace |
| spelling |
irk-123456789-612132014-04-28T03:01:44Z Unsteady flow structure: dual array of spherical and cylindrical dimples Khalatov, A. Byerley, A. Тепло- и массообменные процессы Выполнена экспериментальная программа в Военно-воздушной академии США, направленная на изучение нестационарной структуры потока перед, внутри и за двойным рядом “мелких” (h/D = 0,1) сферических и цилиндрических углублений на плоской поверхности. Сравнение показало, что первый ряд углублений “подавляет” флуктуации второго ряда. Виконано експериментальну програму у Військово-повітряній академії США, скеровану на вивчення нестаціонарної структури потоку попереду, всередині та за подвійним рядом дрібних (h/D = 0,1) сферичних та циліндричних заглиблень на плоскій поверхні. Порівняння показало, що перший ряд заглиблень “пригнічує” флуктуації другого ряду. The experimental program was performed in the U.S. Air Force Academy to obtain details of the unsteady flow structure in front, within and downstream of a dual array of shallow (h/D = 0.1) spherical and cylindrical dimples on a flat plate. Comparisons have shown that the first row “suppresses” fluctuations of the second row. 2007 Article Unsteady flow structure: dual array of spherical and cylindrical dimples / A. Khalatov, A. Byerley // Промышленная теплотехника. — 2007. — Т. 29, № 1. — С. 5-11. — Бібліогр.: 6 назв. — англ. 0204-3602 http://dspace.nbuv.gov.ua/handle/123456789/61213 532.516:536.24.01 en Промышленная теплотехника Інститут технічної теплофізики НАН України |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| language |
English |
| topic |
Тепло- и массообменные процессы Тепло- и массообменные процессы |
| spellingShingle |
Тепло- и массообменные процессы Тепло- и массообменные процессы Khalatov, A. Byerley, A. Unsteady flow structure: dual array of spherical and cylindrical dimples Промышленная теплотехника |
| description |
Выполнена экспериментальная программа в Военно-воздушной академии США, направленная на изучение нестационарной структуры потока перед, внутри и за двойным рядом “мелких” (h/D = 0,1) сферических и цилиндрических углублений на плоской поверхности. Сравнение показало, что первый ряд углублений “подавляет” флуктуации второго ряда. |
| format |
Article |
| author |
Khalatov, A. Byerley, A. |
| author_facet |
Khalatov, A. Byerley, A. |
| author_sort |
Khalatov, A. |
| title |
Unsteady flow structure: dual array of spherical and cylindrical dimples |
| title_short |
Unsteady flow structure: dual array of spherical and cylindrical dimples |
| title_full |
Unsteady flow structure: dual array of spherical and cylindrical dimples |
| title_fullStr |
Unsteady flow structure: dual array of spherical and cylindrical dimples |
| title_full_unstemmed |
Unsteady flow structure: dual array of spherical and cylindrical dimples |
| title_sort |
unsteady flow structure: dual array of spherical and cylindrical dimples |
| publisher |
Інститут технічної теплофізики НАН України |
| publishDate |
2007 |
| topic_facet |
Тепло- и массообменные процессы |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/61213 |
| citation_txt |
Unsteady flow structure: dual array of spherical and cylindrical dimples / A. Khalatov, A. Byerley // Промышленная теплотехника. — 2007. — Т. 29, № 1. — С. 5-11. — Бібліогр.: 6 назв. — англ. |
| series |
Промышленная теплотехника |
| work_keys_str_mv |
AT khalatova unsteadyflowstructuredualarrayofsphericalandcylindricaldimples AT byerleya unsteadyflowstructuredualarrayofsphericalandcylindricaldimples |
| first_indexed |
2025-07-05T12:13:13Z |
| last_indexed |
2025-07-05T12:13:13Z |
| _version_ |
1836809028127162368 |
| fulltext |
OBJECTIVE
As reported in [1, 2], the suction side of gas turbine
blade suffers from the boundary layer separation when
operating at the off;design conditions. The separation
and increase in the blade profile losses cause a signif;
icant reduction in the turbine efficiency. To guard
against this, both active and passive flow control tech;
niques are considered. Compared with other passive
techniques (V;grooves; wires), the shallow spherical
dimples have demonstrated the best results in terms of
reduction in separation losses and improvements in
the region of a flow reattachment [1, 2].
There is a vast experimental and theoretical data;
base in the literature involving a single dimple on a
flat wall and multiple dimples in the rectangular
channel. The author refers reader to the extensive
reviews given by Ligrani, et al. [3] and Khalatov [4].
However the application of dimples for the flow sepa;
ration control over turbine blade requires fundamen;
tal knowledge of the fluid flow features for single; or
dual array of dimples at relatively low flow velocity
regimes. For the single array of shallow dimples
(h/D = 0.10) the limited fluid flow database has been
presented by Lake, et al. [1], Rouser [2] (spherical
dimples/turbine blade) and Khalatov, et al. [5]
(spherical and cylindrical dimples/flat plate). There
was no data revealed for the dual array of dimples; as
supposed this configuration provides better wall cov;
erage due to the downstream overlapping of wakes.
The objective of this study is to investigate the
details of unsteady flow features in front, inside and
downstream of a dual array of shallow (h/D = 0.10)
dimples on a flat plate. The experimental program
was performed at relatively low Reynolds number
conditions (ReD < 25,000) using the dye flow visuali;
ISSN 0204�3602. Пром. теплотехника, 2007, т. 29, № 1 5
ТЕПЛО� И МАССООБМЕННЫЕ ПРОЦЕССЫ
Виконано експериментальну програ*
му у Військово*повітряній академії США,
скеровану на вивчення нестаціонарної
структури потоку попереду, всередині та
за подвійним рядом дрібних (h/D = 0,1)
сферичних та циліндричних заглиблень
на плоскій поверхні. Порівняння показало,
що перший ряд заглиблень “пригнічує”
флуктуації другого ряду.
Выполнена экспериментальная про*
грамма в Военно*воздушной академии
США, направленная на изучение неста*
ционарной структуры потока перед,
внутри и за двойным рядом “мелких”
(h/D = 0,1) сферических и цилиндричес*
ких углублений на плоской поверхности.
Сравнение показало, что первый ряд уг*
лублений “подавляет” флуктуации вто*
рого ряда.
The experimental program was per*
formed in the U.S. Air Force Academy to
obtain details of the unsteady flow struc*
ture in front, within and downstream of a
dual array of shallow (h/D = 0.1) spherical
and cylindrical dimples on a flat plate.
Comparisons have shown that the first row
“suppresses” fluctuations of the second
row.
UDC 532.516:536.24.01
A. KHALATOV1, A. BYERLEY2
1Institute for Engineering Thermophysics, National Academy of Sciences, Kiev, Ukraine
2United States Air Force Academy, Colorado Springs CO, USA
UNSTEADY FLOW STRUCTURE: DUAL ARRAY
OF SPHERICAL AND CYLINDRICAL DIMPLES
D – dimple projected (surface) diameter, m;
f – frequency of bulk flow oscillations, s–1;
h – dimple depth, m;
H* – channel height, m;
L – extent of in;dimple separation zone, m;
ReD – diameter based Reynolds number, U∞D/ν;
Rex – axial distance Reynolds number, U∞x/ν
Sx, Sz – axial and spanwise dimple pitch, m
Sh – Strouhal number, f · D/U∞
x – axial distance from the leading edge, m;
U∞ – approaching flow speed, m/s;
z – spanwise distance, m.
Greek symbols:
δ – boundary layer thickness, m;
ν – kinematic viscosity, m2/s.
Subscripts:
o – pre;dimple flow parameters.
zation technique. This includes a laminar flow in
front of the first row, but both laminar and turbulent
flow in front of the second row. The shallow dimples
were taken for the experimentation as providing
reduced additional pressure losses. Both spherical and
cylindrical dimple configurations were tested to assess
their relative characteristics.
EXPERIMENTAL FACILITY
Test section
The experimental program was performed in the
U.S. Air Force Academy (Colorado Springs) closed;
circuit water tunnel described by Khalatov, et. al [5].
The water tunnel is capable of operating over a speed
range of 0.07 to 0.52 m/s. The inlet nozzle has a con;
traction ratio of 6:1; the mean velocity at the inlet is
uniform to within ± 2%, the mean flow angularity is
within ± 1.0 degrees in both pitch and yaw directions.
The test channel is 1,830 mm long with a rectan;
gular cross section (610 mm height; 457 mm width).
The sidewalls and floor (bottom) were made of a glass
to allow access for flow observations. The test section
(Fig.1) is an acrylic flat plate with an elliptically
shaped leading edge. It is 19 mm thick, 1,220 mm
long and 381 mm wide.
A dual array of dimples (Fig.1a) was machined in
the test section in the staggered mode using the
isosceles triangle fashion (Fig.1b). The dimple
(spherical and cylindrical) projected (surface) diame;
ter is 50.8 mm, the depth is 5.08 mm providing the
shallow dimple configuration (h/D = 0.1). The cen;
ter of the first row locates at 88 mm from the plate
leading edge to avoid the effect of pre;dimple bound;
ary layer thickness. For the first and second rows the
spanwise pitch is 76.2 mm (Sz/D = 1.5), the axial
pitch between first and second rows is 88.0 mm
(Sx/D = 1.73). Such a configuration provides over;
lapping of wakes (25%) after the dual array of dimples
and much better surface coverage.
The dimpled flat plate in the test section was sus;
pended upside down, so the flow structures could be
observed through the transparent (glass) floor with the
aid of an inclined mirror placed below the test chan;
nel. To visualize the flow structures, five different col;
ors of dye were injected through five cylindrical ports in
front of the representative dimple (Fig. 1c, 1d) and inside
it. Additional three ports were made between adjacent
cylindrical dimples of the second row (Fig. 1c, 1e).
A digital camcorder SONY;DCR VX2000 was
used to record the unsteady flow patterns. The video
images were stored as digital (AVI) files to allow com;
6 ISSN 0204�3602. Пром. теплотехника, 2007, т. 29, № 1
ТЕПЛО* И МАССООБМЕННЫЕ ПРОЦЕССЫ
Figure 1. Dual array of dimples in the staggered mode (no dye ports shown inside the dimple).
puter screening at a reduced frame rate (slow motion)
with Adobe Premiere 6.5 Software. In this way, the
flow structures and patterns could be carefully
observed, analyzed and characterized. From this data
the frequency of the bulk flow oscillations was deter;
mined by counting the number of fluctuations shed by
the dimple during a 15 sec interval [5].
The Reynolds number ReD ranged from 3,260 to
23,450, corresponding to a range of Reynolds num;
bers Rex in front of the first array from 4,010 to
28,840. The laminar flow kept in front of the first
array of dimples, the non;dimensional boundary layer
thickness δ0/h varied from 0.3 to 0.4.
Uncertainty Analysis
Velocity measurements were calibrated to within
± 1.8% using a video camera to record the time for a
volume of dye to go the length of the test section
(video camera frame rate is 29.97 frames per second).
The uncertainty in Reynolds number was estimated to
be within ± 2.4%. The uncertainty in frequency was
estimated to be ± 10.6%, which contributed to an
uncertainty in the Strouhal number of ± 10.9%. At
lower free;stream velocities, both the frequency of
fluctuations and the Strouhal number were as low as
± 3.66% and ± 4.35%, respectively. All uncertainty
estimates are based upon the methods of Coleman
and Steele [6].
DUAL ARRAY OF CYLINDRICAL DIMPLES
A description of the flow patterns inside and down;
stream of a single array of cylindrical dimples has
been considered in [5]. As concluded, the adjacent
dimples strongly influence the flow patterns and
downstream bulk flow fluctuations. At low Reynolds
numbers, the frequency of bulk flow fluctuations are
close to that obtained for a single dimple, although
between ReD = 8,000 and ReD = 10,400 the Strouhal
number drops below that for a single dimple.
Dye injection in front of and within a dimple
The experimental runs were conducted across the
range of the water velocities from 0.072 to 0.52 m/s
corresponding with diameter;based Reynolds num;
bers ReD ranging from 3,265 to 23,450. The non;
dimensional boundary layer thickness δ0/h in front of
the first row was 0.40 at ReD = 5,220 and 0.28 – at
ReD = 16,240. Five different dye colors were injected
through five cylindrical ports machined both
upstream (S1 –, S2 –, S3 – streamlines; Fig. 1c, 1d)
and inside (not shown) representative dimple.
The central S1;streamline in the space between the
first row adjacent dimples revealed a laminar flow
structure in front of the second row in the whole range
of Reynolds number (up to ReD = 23,450). At
ReD ≤ 4,170 both S2 – streamlines were almost paral;
lel to each other, while S3 – streamlines located in the
wake of the first array experienced weak fluctuations.
Fluctuations of S2 – streamlines observed only at
ReD > 5000 (Fig.2a), with the laminar;turbulent flow
transition (streamline destruction) completed by
ReD = 12,250. On both S3 – streamlines the turbu;
lence indicated at ReD = 5,260.
Inside a dimple, the flow began to separate at
ReD > 5,260, the extent of the separated flow area was
increased with growth of the Reynolds number. At
ReD = 6,800 a weak flow rotation occurred inside the
dimple with a small flow fluctuations zone near the
back dimple rim. This might be due to the flow insta;
bility inside a dimple. After ReD = 9,200 the in;dim;
ple separation zone is almost symmetrical. Moreover,
due to the laminar;turbulent flow transition after the
first row (S2 – and S3 – streamlines at ReD >12,250)
the separation zone extent remains approximately
constant at around 50% of the dimple area up to
ReD = 23,450. Unlike this, for the single array of
dimples a separation zone extent increased monoton;
ically with the Reynolds number growth [5].
Downstream of a dimple the flow exhibits a “strip”
pattern (Fig. 2b) at ReD ≤ 4,170, while at ReD = 5,260
the flow transitioned to the turbulent flow (Fig. 2a).
The highly;developed downstream bulk flow fluctua;
tions were observed at ReD > 5,260.
Dye injection between dimples
The flow structure between adjacent dimples of the
second array was visualized to study the flow pattern
after the dimple in the first array. Three cylindrical
ports (Fig. 1c; 1e) were located at the distance of
30 mm downstream of the dimple back edge.
Since this distance is very small (≈0.60·D), the first
row heavily influenced the flow structure. At
ReD < 5,260 the flow kept the laminar structure with
weak flow fluctuations of the S4– streamline. Both
S5– streamlines demonstrated significant spanwise
ISSN 0204�3602. Пром. теплотехника, 2007, т. 29, № 1 7
ТЕПЛО* И МАССООБМЕННЫЕ ПРОЦЕССЫ
fluctuations. Based on the observations of dye behav;
ior, the conclusion was made that the turbulence on
the S5 – streamline started at ReD = 6,850, while on
both S4 – streamlines – at ReD = 8,140. For a single
array of cylindrical dimple the downstream laminar;
turbulent flow transition began at ReD = 6,670 [5].
This value of the critical Reynolds number is close to
that obtained for S3 –, S4 – and S5 – streamlines.
At ReD > 9,300, both S5 – streamlines moved in
towards the second array, however at ReD>15,000
the streamlines were fully “sucked” into the dimple
area. This is a clear evidence of the cross flow talk;
ing between dimples located in the first and second
array.
Laminar – turbulent flow transition
The experimental results considered above led to
the following primary conclusions:
At ReD < 5,260 the flow structure is the lami;
nar one throughout the flow area.
In the area between ReD = 5,260 and
ReD = 12,250, the flow between adjacent dimples of
the first row is laminar, but is turbulent beyond the
dimple in the first row. After the second array it is the
fully developed turbulent flow.
At ReD > 12,250 the flow was the turbulent
one throughout the flow area.
Flow conditions in front of a dimple influence
weakly the critical Reynolds number after a dimple.
Beyond a single array the flow became turbulent at
ReD > 6,670 (laminar flow in front of), while beyond
a double array – at ReD> 5,260 (laminar flow accom;
panied with a wake from the first array dimple; greater
boundary layer thickness).
Bulk flow fluctuations
The correlation Sh = f (ReD), describing the bulk
flow fluctuations downstream of the dimple in the
second array is shown in Fig.3. For the single and
double arrays the correlation Sh = f (ReD) is a curve
with a maximum at a certain Reynolds number
(Remax). Therefore, at Re < Remax the growth of fre;
quencies of flow fluctuations dominated over the
water velocity growth, and vice versa at Re < Remax.
For the single array, the correlation Sh = f (ReD)
reaches a maximum at ReD ≈ 10,200, while for the
double array – at ReD ≈ 10,000. However the single
array has a sharp peak in the Strouhal number curve,
while the double array – a much broader peak.
Unlike the single row, the flow fluctuations beyond
a second row did not occur at ReD < 3,000. As a
whole, the fluctuations generated by the second row
were lower than those generated by the single row.
This is due to the complex flow structure, transition to
the turbulent flow and greater boundary layer thick;
ness in front of the dimple, as well as lower in;dimple
separation zone extent. At ReD>20,000, flow fluctua;
tions (Strouhal number) for both configurations are
actually identical, therefore no influence of the
upstream flow structure occurred in this Reynolds
number regime.
As reported, the double array provided the down;
stream laminar;turbulent flow transition at ReD > 5,260,
while in the space between dimples – at ReD > 8,140.
8 ISSN 0204�3602. Пром. теплотехника, 2007, т. 29, № 1
ТЕПЛО* И МАССООБМЕННЫЕ ПРОЦЕССЫ
Figure 2. Dual array of cylindrical dimples (second row). а: ReD = 5,260. b: ReD = 4,170.
Dye injection in front of (a) and inside a dimple (b).
a b
The single array provided transition after a dimple at
ReD > 6,670 with laminar flow between adjacent dim;
ples. Therefore, at ReD > 8,140 the double array gen;
erated the downstream turbulent flow throughout the
flow field. This important fact can be employed in
design of the flow separation control devices.
DUAL ARRAY OF SPHERICAL DIMPLES
Description of the flow patterns for a single array of
spherical dimples has been considered in [5]. As
found, across the whole range of Reynolds number
the Strouhal number is approximately 10% greater
than for a single dimple. However for both configura;
tions the “peak” of the Strouhal number curve was
occurred at ReD ≈ 16,300.
Dye injection in front of and within a dimple
The experimental program was performed across
the same range of fluid boundary conditions as for the
dual array of cylindrical dimples.
At low flow velocities (ReD = 3,310) the S1–
streamline over a dimple was parallel to the axial flow
direction, while S2 – and S3 – streamlines demon;
strated weak spanwise fluctuations. At ReD > 10,500,
the streamlines over the dimple experienced substantial
spanwise fluctuations, especially noticeable in the dim;
ple axis area. At higher flow velocities (ReD>12,250)
the streamlines were twisted and broken.
Inside a dimple the unsteady flow pattern appeared
at ReD = 5,500 with periodic downstream bulk flow
fluctuations. At higher flow velocities, these fluctua;
tions increased, so the bulk flow fluctuations were
almost regular at ReD = 7,940. At ReD = 9,480 the
asymmetric twin vortex action began inside the dim;
ple, which transformed into a symmetrical twin vor;
tex pair at ReD = 12,250 occupying around 50% of the
dimple area. At ReD = 17,050 the twin vortex pair
started to dissipate into the chaotic streamline pat;
terns. This chaos increased with increases in flow
velocity leading to a fully chaotic flow in upstream
dimple area. At ReD = 23,450 the in;dimple separa;
tion zone extent was around 70%.
Downstream of a dimple, the streamlines fluctuat;
ed in the spanwise direction; increasing the flow
velocity led to the growth of spanwise fluctuations and
transition to turbulent flow at ReD = 9,480.
Laminar-turbulent flow transition
Results given above show that S1– and S2 –
streamlines in front of the dimple kept the laminar
flow pattern up to ReD = 23,450, while S3 – stream;
line demonstrated transition to the turbulent flow at
ReD > 9,480. Turbulence and a wide wake down;
stream of a dimple was detected at ReD > 9,480. This
transition links with the asymmetric flow pattern
inside a dimple. As far as the single dimple and single
row of dimples is concerned, the flow transition after
dimple(s) occurred at ReD > 7,940…7,980 [5].
Bulk flow fluctuations
The correlation Sh = f (ReD), demonstrating the
bulk flow fluctuations downstream of the single; and
double array of spherical dimples is presented in
Fig.4. Again, this correlation is a curve with a maxi;
mum at a certain Reynolds number (Remax). In both
ISSN 0204�3602. Пром. теплотехника, 2007, т. 29, № 1 9
ТЕПЛО* И МАССООБМЕННЫЕ ПРОЦЕССЫ
Figure 3. Bulk flow fluctuations: single (1) and dual (2) array of cylindrical dimples.
cases, the curve Sh = f(ReD) reached a maximum at
ReD17,200. The broader “peak” in the Strouhal num;
ber curve can be explained by the “smooth” shape of
the spherical dimple. As for the cylindrical case, the
frequencies for the double row are less than for the
single row, particularly at ReD< 15000. The reduction
for the spherical dimple case actually looks greater
than for the cylindrical dimple case shown in Fig.3.
Unlike the single array, the flow fluctuations beyond a
second array did not appear at ReD < 4,500.
СOMPARISONS
A comparison of the bulk flow fluctuation frequen;
cies generated by the cylindrical and spherical dim;
ples in the single;row mode is presented in Fig.5. For
both configurations, the magnitude of Strouhal num;
ber maximum is approximately the same, however for
the spherical dimple this maximum occurs at a greater
Reynolds number. At ReD < 7,500 and ReD > 12,500
the spherical dimple generates more significant bulk
flow fluctuations.
Bulk flow fluctuations generated by the second row
are given in Fig.6. At ReD numbers ranging from
5,000 to 13,000, the fluctuation frequencies of the
cylindrical dimples exceeded those for spherical dim;
ples. However, at ReD > 20,000 there was no effect of
the dimple shape on the magnitude of the Strouhal
number. For both configurations, the maximum value
of Strouhal number is approximately the same.
10 ISSN 0204�3602. Пром. теплотехника, 2007, т. 29, № 1
ТЕПЛО* И МАССООБМЕННЫЕ ПРОЦЕССЫ
Figure 4. Bulk flow fluctuations: spherical dimples.
Figure 5. Comparisons: bulk flow fluctuations downstream of a single array of dimples.
1 – cylindrical dimples. 2 – spherical dimples.
CONCLUSIONS
For the dual and single array the dimple shape (spher;
ical/cylindrical) plays important role in the level of
downstream bulk flow fluctuations. For the spherical
dimple the “peak” in the curve Sh = f(ReD) is broader
than that for the cylindrical dimple. The upstream vor;
tex structures reduce bulk flow fluctuations after the sec;
ond row making them smaller than those after the single.
According to visual flow observations transition to
the turbulent flow after cylindrical dimples occurred
at ReD= 5,260, while beyond spherical dimple – at
ReD= 9,480. As follows (Fig. 6), for both configura;
tions this transition corresponds to the “narrow”
range of Strouhal number from 0.6 to 0.7.
ACKNOWLEDGMENTS
This research was performed while visit of Prof. A
Khalatov to the Aeronautics Laboratory of U.S. Air
Force Academy in Colorado Springs (U.S. National
Research Council Grant). The partial support of CRDF
Grant # UE2�552�KV�02 is also acknowledged.
REFERENCES
1. Lake J.P., King, P.I., Rivir R.B. Low Reynolds
Number Loss Reduction on Turbine Blades with
Dimples and V;Grooves // AIAA Paper № 00;738. –
2000.
2. Rouser K. Use of Dimples to Suppress
Boundary Layer Separation on a Low Pressure
Turbine Blade. – M.S. Thesis. – Air Force
Institute of Technology. WPAFB, Ohio, USA. –
2002.
3. Ligrani P.M., Oliveira M.M Blaskovich, T.
Comparison of Heat Augmentation Techniques //
AIAA Journal. – Vol.41. – №3. – 2003. – pp.337;
362.
4. Khalatov A., Borisov I., Shevtsov S. Heat
Transfer and Hydrodynamics in Centrifugal Fields.
Volume 5: Heat and Mass Transfer, Thermal;hydraulic
Performance of Vortex and Swirling Flows. – Kiev:
National Academy of Sciences of Ukraine. –2005. –
500p. (in Russian).
5. Khalatov A., Byerley A., Seong�Ki Min, Ochoa D.
Flow Characteristics Within and Downstream of
Spherical and Cylindrical Dimple on a Flat Plate at
Low Reynolds Numbers // ASME Paper №GT2004 –
53656. – 2004.
6. Coleman H. Steele G. Experimentation and
Uncertainty Analysis for Engineers. – John Wiley
& Sons. New York, NY. 2d Edition, – 1999. –
275p.
Получено 13.07.2006 г.
ISSN 0204�3602. Пром. теплотехника, 2007, т. 29, № 1 11
ТЕПЛО* И МАССООБМЕННЫЕ ПРОЦЕССЫ
Figure 6. Comparisons: bulk flow fluctuations downstream of a dual array of dimples.
1 – cylindrical dimples. 2 – spherical dimples.
|