CFD Investigation of the Interacting Flow And non symmetric jets in cross flow.pdf

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AIAA-86-0280

Investigation of the Interacting Flow

of Non-Symmetric Jets in Cross Flow

J. M.

Wu, A .

D.

Vakili and F.M. Yu

Univ.

of

Tennessee

Space

Institute

Tullahoma,

T N

AIAA 24th Aerospace Sciences Meeting

January 6 9, 1986/Reno, Nevada

02-01 15-012-8 6

-

For Permission to CODY or republish. contact the American Institute

of

Aeronautics and Astronautics

_

1633 Broadway New York.

NY

10019


2/12

INVESTIGATION OF THE

INTERACTING FLOW

O F NON-SYMMETRIC

JETS IN

CROSS FLOWt

J . M. Wu*

,

A.

D.

Vakili**, and F. M.

Yu***

The University of Tennessee Space Institute

Tullahoma, Tennessee

37388

w

Abst,ract

Asymmetric jets

in

cross-flow provide interesting The motivation of t,his study reported herein

interacting flow fields which contain many vortices. stems

from our previous

inve8tigation(2)

of

using dis.

These vortices vary significantly with variations of the jets blowing

fro,,,

the

wing

tip

for improving

jet and the cross flow

and under

certa in specific condi- the wing

aerodynamic performance.

When discrete

tions shedding vortices appear

and

disappear period- jets were applied at

a

wing tip

on

a rectangular wing,

ically. Four different cross section geometry je ts were it in lift improvements with small

studied and compared with a circular cross section jet

j,. blowing momentum coefficients. It was

with the same jet port exit area. Various flow visual- that the entire

wing

circulation has

been

altcrcd(3),

ization techniques were used to aid in understanding This

was

evidently

the

result

of

interaction

of flow

of

the highly three dimensional and complex

flow

field.

around

the wing with the

wing

tip jets. The wing tip

Among m w orms

of

secondary vortices produced jets were blown from rectangular exit cross sections

four major vortices were identified in general. The

(Figure

I) ,

and therefore were believed to be essen-

most notable and interesting kind was the spin-off tial for understanding the whole flow ficld of

t h e

wing

vortices observed previously in our study of discrete tip jet.s. The major axis

of

recta npla r jet port was

je ts blowing from a wing tip . These shedding vortices placed parallel

to

the wing chord line, SO that. the in-

were formed under certain flow conditions

and

jet ori-

dividual jet ports inclined to the local

oncoming

entations. The shedding vortices were nearly parallel

free

strealll

f low as

shown in pigure

1.

verious

pccu.

to the jet exit axis with periodicity depending on the

1iarly behaving atixiliary vortices were obscrved (Fig-

jet to the free stream velocity ratio.

A

reconstruction

2 ) .

It was suspected that the noll.symmetric jet

of

the asymmetric flow field based on observations

in

cross f low

by yawing a

symrnctric lon-

and

its evolution

and

relationship with established

gated jet port, caused these vortices. Consequently,

symmetric jet in cross flow were made. Unsteady jet s the study was under taken to investigate

the

flow ficld

created by pulsation

of

the jet flow at low pulsation

of jets in uniform

crossflow

frequencies behaved significantly differently

than

the

steady jets.

I.

Introduction

-

Undoubtedly such asymmet,ric

flow

fields may he

encountered in many actunl occurrences in the nature

or in the engineering applications. As

a

simplest

ex

ample one

may

think of

a

situat ion for

a

vertical jet

ta ke of f aircmft with the jet hlown from non-circular

jet.

ports (say rectangilar) cnrountering a

cross

wind

which is not aligned

to

rithrr of their major axes.

With the courtesy of Prof. G . Carrier of

Harvard

University, we obtained a photograph showing an oil

rig which

caught

fire in a

strong

wind

over

the occan.

Another example t.hat ocrur rcd in nature, can bc seen

in Fignrc.

3.

Judging hy the si x of a nearby ship,

t h e

Reynolds nunil)cr involvrd in this

pho t o ) case

must

be

very

large.

Thr

jet

(smokc) plumc

with cross wind

induccd many vortices which

arc very similar

to what

wc

have

o1)scrvcd

in the water tunnel cxpcrimrnt,s on

asymnictric jets (see typical flow ficld shown in Figure

4 .

Thrrrforc , thr phenomenon

oliservcd

in this

study

is not only limited to modaratcly small R.cynolds mini-

hw as

apparent.

Jets

in

a

flow are of practical

interest

to

many engineering fields. From the VSTOL aircraft

in

a transition flight

to

the waste disposal into water

bodies

or to the

atmosphere,

the

characteristics of jets

in

cross

flow play a dominating

role.

Consequently, a

large volume of literature have been devoted to this

topic and many basic

out

in

the past (see for instance, a survey by Rajaratnam()

in

1916 and subsequently

many papers

scattered

in

various

journals),

In

spite

of extensive

investi-

gations on t,he subject of je ts in cross

f low,

recently we

have encountered a problem which has not received

proper attention anywhere, to our knowledge.

have heen

t

This paper describes partial results.

Work supported by AFOSR, Grant

84-0114

with

Dr.

James

D.

Wilson, technical monitor

is gratefully acknowledged. Thcre

have

been many investigations performrd

on circular jets in rross flow and limited studies on

I. /

Associate Fellow, AIAA rcctanbalar jets oriented syminctrically aligned with

oncoming flow 4-8). Vortiws shedding from

such

flow phcrionirna haw bccn shtdicd iii dcttiil in tlu,

B . H.

Goethert Professor Director,

Senior Research Engineer, Member, AIAA

Graduate Research Assistant, Member, AIAA

- 1 -


3/12

past. Some are also relevant to the present asym-

metric jet s tudy. Moreover, the Karman vortices and

wake instability of How over

a

cylinder

or

bluff-bodies

are relevant to the problem. These are discussed

where appropriate in this paper.

The present study concentrates

on

the detail fea-

tures associated with the non-symmetric jets in cross

flow and which could be enhanced by proper geomet-

rical modification

or

introduction

of

periodic rxcita-

tions, to aid the wing

tip

jet flow interaction effects.

11.

Experimental Description

At the onset, the basic goal of

this

study

was

to

understand basic flow phenomenon which may lead

to design jet shapes whose flow field would resemble

some of the key flow features observed in the wing

tip jet How study as described in the introduction. In

order to avoid added complexities of the near wing

tip flow field, the problem has been simplified to non-

symmetric jets blown perpendicularly from a f l t p la te

into uniform cross flow.

Five jet ports with different geometry cross sec-

tions but with equivalent cross sectional

area

were

designed

and

manufactured. Figure

5

shows the di-

mensions and coordinates

for

these jet ports. These

five shapes are numbered and named for ease of refer-

ence. Number one jet which is the circular jet, is the

basic reference geometry.

A

large number of studies

and measurements are available

for

the circular jet in

cross

flow

hence it

is

naturally a good geometry to be

used for comparison with observations on the other

four jets.

Each jet was installed on the water tunnel floor to

a modular common base extending into the tunnel 1.9

em

(0.75

in) where the jet exit was flush mounted onto

a boundary layer split ter plate. The splitter plate

was 150 cm (60 in) long and

was

extended 19 cm

(7.5 in.) upstream of the jet port center to allow for

the development of the flat plate laminar boundary

layer. The modular components mechanism allowed

adjustments to be made in the orientation of various

jets only in the plane of jet exit with respect to the

uniform cross flow. Therefore, the je ts were always

perpendicular to their exit plane

or

the tunnel Roar,

but could be easily rotated to create yaw angles of

= 0

to

180

Figure 5b.

The UTSI water tunnel is a closed circuit, con-

tinuous flow facility especially designed for low turbu-

lence and high quality

How

visualization. The tunnel

lies

in a

horizontal plane and is powered by a twin

bladed propeller in the return log of the tunnrl cir-

cuit. The tunnel free stream speed is varied from 1.5

cm/sec. to 60 cmlsec by changing the propeller rota-

tional speed. The Reynolds number based on the jet

Two types of flow visualization techniques have

bcrn used to extract maximum information from the

How

field. The first

is

by using regular milk and dye

tcchuique. Dye wa s a mixture of alcohol, milk, and

commercial food coloring in such a way to ensure spe-

cific gravity equivalent to water. The second typc

is the laser induced fluorescence technique. Three

chemicals were used: Rhodamine 6G hodamine B

and Fluorescein Sodium Salt. Once dissolved in water

and under the excitation of laser light; yellow, red and

green fluorescent colors were made visible. Dye was

injected to the specific areas of the model at controlled

rates desired for each dye exit port . Many distributed

small dye exit ports were built into the plate and jets

exit neighborhood

so

the dye could be introduced at

the desired points

on

the surface. Small dye probes,

capable of being positioned inside the How were also

used to introduce dye at regions of Row which the

surface dye was not carried to.

diameter was in the range of 200 to

500.

Test section

dimensions are 35.6 cm high, 45.7 cm wide and 150

cm long (14

in x

18 in x 60 iu). The test section walls

are made of Plexiglas for versatility in observing and

photographing the How field. The experimental sewp

is schematically shown in Figure 6.

An Argon ion laser light source

1

to 2 watts

power) was used for the laser fluorescence flow visu-

alization. A 4mm cylindrical lens in front of the laser

beam produced

a

plane laser light sheet. Rotat.ion

of

the cylindrical lens resulted in rotation of the light

sheet plane. Combined translation and rotation

of

the

light sheet plane provide visibility into the complete

How field at any desired orientation. Frequently the

dye for laser How visualization was introduced into

the jet fluid itself. In this way

it

became possible to

observe the jet Huid deformation directly, which

was

not visible otherwise. On the whole the two How vi-

sualization techniques complemented each other for a

complete observation of the details. The general ar-

rangement of experimental set up is shown on Figure

6and the coordinates system is shown on Figure 5b.

In order to study different jet entrainment and

intrract ion effects, the tunnel velocity and the area-

averaged jet exit velocity was chosen such that the

vrlority ratio was 1

5 Q/V- 5

7. For each jet the

major axis of jet cxit model was adjusted and the rel-

ative yaw angle was varied to study the vortical

flow

intrract ion effects. The pulsation

of

jet at frequencies

between 1 Hz to 16 Hz were applied. An oscillating

small rectanvilar in the wake of jet were also used to

amplify the periodic vortical flow interaction effects.

Various observations made and the resulting analysjs

of th r How visualization study are discussed in the

following sections.


4/12

111. Princiule Observations

1. Jet Vortices

Jets in uniform cross flow are acted on by the

momentum of the cross stream from the point of exit

until complete balance and alignment between the

two flows are reached. Due to the bending curva-

ture and pressure gradient generated, the jet. fluid

with the entrained cross flow form two distinct vor-

tices (secondary flows, called Prandtl s first kind

( 1).

For a

symmetric jet in

a

uniform cross stream these

two vortices are symmetrically generated with the jet

wake

also

being symmetric. These observations have

been made in many studies as noted earlier.

-

If the jet forms a non-symmetric configuration

with the cross flow, the resulting flow field around

the jet and in the downstream is highly asymmetric,

three-dimensional and usually unsteady. Various vor-

tices arc formed and their interactions with the wake

flow produces

a

highly complex flow field. The je t

vortices, under this conditions are not symmetric and

their st rength are different. Also, the je t fluid

is

acted

on by the non-uniform cross flow momentum, hence

the two jet vortices follow

two

different trajectories.

All

these, introduce

a

significantly different flow field

compared to the symmetric jets.

By introducing colored dye from appropriat,e

lo-

cations near the jet exit, it is possible to make the

major vortex cores visible. These traces also corre-

spond to their mean trajectories. A typical illuistra-

tion of these major vortex trajectories can be seen in

Figure

7.

This side view photo

wa s

taken with mod-

erately high jet to free stream velocity ratio of

3.70

with

a

short tear

drop

shape jet port (model

4

yawing

at

p

= 30

relative to oncoming free stream. Three

distinct major vortex systems could be identified

un-

der the above

flow

and the jet orientation conditions.

The most penetrated wind side jet-vortex appeared

to be the strongest one, and usually less visible in the

down-stream with regular dye due

to

stronger entrain-

ment of the cross flow and local higher turbulence

level, (with the laser-fluorescence flow visualization,

this vortex flow became very distinct , however).

-

If

the jet to free stream velocity ratio was de-

creased all three vortices were lying closer to the

flat

plate and less distinguishable

as

they were closer,

weaker and nearly merged together. Once the yawing

angle

@

was decreased the jet-vortices represented by

the upper two trajectories followed similar path and

appeared to coincide from the side view. This was ex-

pected

as

the jet-vortices appeared to be almost sym-

metric for decreasingly yaw angle 8 .

For

increased

jet to free stream velocity ratio the jet-vortices reprc-

sented by the upper two trajectories penetrated fur-

ther away into the free stream. At the mean time, it

-

appeared that an additional pair of less distinct vor-

tices also were formed from the jet exit to join the

major stronger wind sidc jet -vortex flow. In other

words, there is a possibility of forming more major

vortex systems with higher velocity asymnictric jei in

cross

flow. This

is

yet to

be

confirmed with furthcr

study.

Surface

flow

pattern in the downstrcam of the

teardrop shape jet (model

3) is

shown in

a

top view

photograph. in Figure

8.

Even though the jet is is-

sued perpendicnlar to t,he surface, the surfacc wakc

is dominated by the non-uniform entrainment hence

non-symmetric. The surface shear stress lines, visual-

ized by placing

dye

upstream on the plate around the

jet, are

used

to help thc intespretation of flow

field

near the flat pla te surface. The flow field near the

plate rescmhles that

of

a wing at an incidcnce to

a

uniform Row

Figure

9

shows the duvelopmcnt

of

jet-vortices for

a

tcar-drop shape jet (model

3)

at various downstream

distances. These photos arc taken in a planr inclined

5 O

toward the oncoming flow using laser fliiorcscencc

flow visualization technique. This figure shows how

the jet fluid

is

deforming into the jet-vortices and

demonstrates the formation of a wake-vortex near the

flat plate surface.

Based on evidence described above, the explana-

tion of how the flow developed from a symmct.ric jet

to a non-symmetric jet in cross flow is given in Figure

10. With the aid of an imaginary plane ( A ) , a pair of

jet-vortices and a pair of wake-vortices can bc seen. If

the jet

is

symmetric, these two pair of vortices would

bc symmetric

as

schcniatically illustrated in Figure

loa. With

a

lion-symmetric jet yawed to oncoming

flow,

on the

same

plane

( A ) ,

thc wind side jet-vortex

moves away from the base plate

and

the lee sidc jet-

vortex moves closer

t,o

thc platc which would result in

enhancing the Ice sidc wake-vortex and degmrrating

the wind side wake-vortex as shown in Figure lob.

The pair of wake-vort.ices arc the product.

of

induced

flow

by the countrr rotating jet vortices near the plate

(it is not shown here but our laser-fluorescence pho-

tos have clearly shown this wakc vortices formation).

Figure 10 explains thc sense of rotat ion for the wakc-

vortex being the wind side jct-vortcx. Notc herc that

the shearing to the jet fluid would

be

quite differmt

on the wind and thc lee sides. This explains why thcrc

are three distinct vorticcs in the flow

field of

Fibwre

7.

For

a tear drop shape cross section jet posi-

tioned in thr

cross

flow, with the narrow

end

forward

p = 180 ),

the observed

How

field is shown in Fig-

ure 11. Undcr cross

flow

shearing cffcct o n the jct

in a symmrtrical manner there arc vorticcs forming

arouiid it and shcd from thc jet trailing cnrl in an

3 -


5/12

alternating bu t symmetric manner. Figure

11

shows

cross sections of jet

flow

developing,

in

parallel planes

at 45O to the

Rat

plate, after the jet exit into the

downstream.

1.1 Unsteadv Jet Vortices

The existence of periodicity in the Row behind

jets

in

cross flow has been reported by many investi-

gators before, for instance, Gordier

( l o ) .

McAllister

I1)

related the shedding frequencies of vortices due to

cross

Row

and

a

circular jet with the Struhal number

based

on

the jet diameter. Reilly 4 dentified two

eddy groups shed periodically from different regions

of

the jet.

In

the present non-symmetric jet study it was

found that under certain Row conditions especially

at higher jet to free stream velocity ratios, periodic

shedding vortices were observed

in

the downstream of

asymmetric jet s in the cross Row (Figure 12). These

periodic vortices were initiated

on

the jet wind side

through shearing generated at the interface between

the jet Row and the uniform cross Row.

These types

of

periodic vortices were observed

primarily for the jet models

2,3

and

4

at relative yaw

orientatioqof

O

to

30

o the tunnel free stream and

wi th

the jet t o the tunnel velocity ratios of higher than

three

( q / V m

> 3).

Figure

12

shows two typical pho-

tographs of the flow containing the periodic vortices.

We have labeled these

as

spin-offn vortices, this ter-

minology was borrowed from our wing tip work

(2,3),

and is due to the similarities between these vortices

and the spin-off vortices observed there. The spin-off

vortices shared

a

common root, with their other ends

entrained into the steady je t vortices. The strength

and shedding frequency

of

these spin-off vortices ap-

peared to increase with the je t velocity or its velocity

ratio

V;./V=.

Boldman et al

( 1 3 )

studied two dimensional vor-

tices shedding from

a Rat

plate blunt trailing edge

with equal

and

unequal velocities applied

on

both

sides of the plate. They found that symmetric

and

al-

ternating Karman vortices appeared in t he wake with

equal velocities applied as is expected. Howevrr, by

decreasing the velocity only

on

one side of the plate,

it resulted

in

degenerating the strength

on

that side of

vortices. And in the limit it was possible to eliminate

completely that side of vortices altogether.

This analysis could be used to explain the result

of present observation of the spin-off vortices shed-

ding from the

wind

side

of

jet only and with the same

sense of rotation. Referring to Figure 10, one would

expect

a

higher shear

on

the wind side

of

jet surface

than

on

the lee side. This would be more profound

with moderately increasing the jet velocity and with

a moderately yawing angle

p

which would provide a

larger shearing surface. The shedding frequency ap-

peared related to the jet velocity to the free stream

velocity ratio and the jet orientation. In the lee side

of t he je ts ce rtain periodicity

was

present

in

the sep-

arated Row which was either coupled with the vor-

tices and the shedding frequencies or was influenced

by it, since the frequency of the wake unsteadiness

and shedding were the same.

W

Typical common root of the spin off vortices is

shown in the various figures, we named this as the

jet wake-vortex in the previous subsection. Both

laser-fluorescence and the regular dye indicated the

jet wake-vortex was ini tia ted from the lee side of the

jet and developed parallel to the jet vortices bu t close

to

the Rat

plate . The wake-vortex

wa s

visible for mod-

erate to higher jet Row rates only

for

non-symmetric

jet configurations.

When spin-off vortices were present, they ap-

peared to roll around each other and the wake-

vortex.

It

should be noted here that many investi-

gators

14-1)

have observed also similar

rolling

up

vortices in observation of the wake

Row

structure be-

hind

a

cylinder with its axis perpendicular to a flat

plate in uniform cross flow.

In

Tanedas observation

ti4 ,

he explained tha t vortices from the end of a cylin-

der muat rotate

in

alternating sense a nd connected

to

symmetrical s trength yet alternatively shedding Kar-

man vortices behind the cylinder.

In

our present ob-

servation, the wake-vortex bundled with spin-off vor-

tices were always rotating in the same sense as that

of

the wind side jet-vortex flow. Figure

13

shows a

schematic

of

various features of the asymmetric Row

field.

To

clarify the relationship between unsteadiness

in the j et wake and the spin-off vortices, artificial

pe-

riodic perturbations of various frequencies were

pro-

duced in the lee side of the jets.

As

a result of the

added periodicity, vortices very similar to spin-off vor-

tices were shed for asymmetric jets and for frequen-

cies corresponding to the

wake

fluctuations. Figure

14

shows two flow fields, indicating the difference due

to the added perturbations. The perturbations were

created by oscillating

in

an angular manner, a cylin-

drical rod

at

the tip of which a small

Rat

plate

wa s

installed. The 6mm by 4mm rectangular

fin

was po-

sitioned at the t,ip of the 3mm diameter rod and its

presence in the wake, while not being rotated,

did

not

influence the flow considerably.

2 .

Pulsating Jet

In

order to investigate the effect of jet Row pe-

riodicity on the resulting Row field and especialiy

on

the various vortices in the down stream, pulsation was

applied to the jet Row. A frequency generator and a

- 4 -


6/12

solenoid valve were used t o introduce pulsation in the

jet. That

is,

the continuous jet

wa s

replaced by a

pe-

riodically blown je t. The circular jet (model l ) and

the tear drop jet shape (model

3)

were subjected to

v

variable frequency pulsations.

At low frequencies,

1 Hz

to 4

Hz,

the jet pene-

tration into the cross flow significantly increased for

both models 1 and

3.

Vortex rings were produced

by the pulsation

at

1

HZ

which actually impinged

on

the tunne l top wall. The vortex rings were symmetric

for the circular jet but they had a complicated shape

for the tear drop shape model 3. The vortex rings of

this model were also rotating around the axis of the

jet along which they were moving into the cross flow.

The increased penetration of the jet is believed to

be due

to

the increased momentum in the jet pulses,

since the mean flow rate

was

maintained constant.

As the frequency of the pulsation increased, grad-

ually the flow field returned to the normal pattern

with not much difference from that of the steady jet

including its penetration height. At low pulsation fre-

quencies, spin-off vortices were not observed for the

tear-drop shape jet. But, they reappeared as the fre-

quency of pulsation increased beyond

16

Hz. A qual-

itative representation of the jet plume center trajec-

tory is shown in Figure 15.

3.

Swirline: Je t

Two different techniques were used to introduce

swirl into the jets. First, th e flow was rotated in the

plenum chamber prior to the jet exit. This technique

was not very successful. Second, turning vane was

placed inside the jet just before the exit plane. The

flow following the vane would turn by itself. In both

cases the turbulence level of the jets were increased

considerably. This was evidenced from the rapid mix-

ing

of

the dye in the flow and made observation dif-

ficult. Introduction of swirl in the jet was found to

reduce the effective jet velocity to the free stream ve-

locity ratio.

The second technique, noted above, probably

produced more swirl and showed to be more effec-

tive for the circular jet model

1.

Due to the swirl in

the jet, the flow of circular jet was not symmetric any

more. However, its extent of asymmetricity was not

as

strong as altering the jet port shape and jet

flow

as observed earlier.

IV. Concludina Remarks

The flow field of jets in cross flow of four differ-

ent cross section geometry jets have been studied and

compared with that of a circular cross section jet.

The jets had equal cross section areas but different

geometries. This qualitative study was conducted in

a water tunnel for detail flow field visualization. The

flow around asymmetric jets in cross flow is

of

a very

complex nature and contained many features which

were significantly different than that

of

symmetric jets

in cross How. The How field has been reconstructed

schematirally with explanation given.

Periodic vortic.es were observed perpendicular to

the cross flow, these were called spin-off vortices.

Spin-off vortices were only observed for asymmetric

jets and appeared only at jet velocity to the free

stream velocity ratios usually higher than

2 .5

or 3

and

depending

on

jet port shape and orientation.

Perturbations introduced in the wake of asym-

metric jets produced the spin-off vortices artificially,

only when

the

frequency of the perturbations matched

the separated wake

How

fluctuations. The amplitude

of the natural fluctuations was no t sufficiently large

enough to cause the vorticity created due to shearing

between the jet and the cross flow to shed under such

situation.

A wake-vortex was observed

for

asymmctric j ets

which was lying parallel and close to the floor plate.

Onre

the spin-off vortices were present they became

twisted and linked near the Hat plate and wrap around

the wake-vortex.

Low frequency of the jet flow resulted in forma-

tion of vortex rings which penetrated into the main

flow more than the jet for high pulsation frequencies.

Under this condition no spin-off vortices could be pro-

duced. At higher pulsation frequencies (f

>

lGHz ,

the flow fields were similar to tha t of the steady jets

with

increased mixing present

at

the jets boundary.

Introduction

of

swirl in

the

jet

flows

was

found

to

in-

crease thc jet turbulcnce and to reduce the cffective

jet velocity to the free stream velocity ratio.

There appears to be quik somc similarities

be-

tween

j e t

flows and thc flow around asymmetric cylin-

drical bodies in uniform cross How (Ref. 17) . The

presence

and

the identification of these f low features

is considered to be a first step toward their full nn-

dcrstandiug,utilieation,

cnhmcemcnt

or

suppression

of selected desired vortices in many fluid mechanics

situations.

References

1.

Rajaratuam,

N.

Turbulent Jets, Amsterdam;

New York: Elscvier Scientific Pub.

Go.,

Chapter

9, pp.

184-210,

1976.

2. Wu, J . M. and

A .

D. Vakili, Wing Tip Je ts Aero-

dynamic Performance, Proceedings of the 13th

International Council

for

Aeronautical Science,

Edited by D.Laschka and R. Staufeubicl, Seat-

tle, Washington, August

1982.

- 5


7/12

3.

Wu, J. M., A. D. Vakili and F. T. Gilliam;

In-

vestigation on the Effects of Discrete Wing Tip

Jets, AIAA Papcr No.

83-0546,

AIAA

21st

Aerospace Science Meeting, Reno, Nevada, Jan-

uary

1983.

4 .

Weston, R. P., F. C. Thames, Properties of

Aspect-Ratio-4.0 Rectangular Jets in a Sihsonic

Cross Flow, AIAA Journal, Val.

16, No . 10,

pp.

701-707,

October

1979.

5.

McMahon, H. M., D. D. Hester, J. G. Pslfeiy,

Vortex Shedding From a Turbulent dc t in a

Cross Wind, Journal of Fluid Mcchanira, Val.

48,

Part

1 , pp. 73-80, 1971.

6 .

Wu,

J.

C .

Experimental and Analytical In-

vestigation of Jets Exhausting Into a DeHrcting

Stream; AIAA Paper No.

69-225,

AIAAIAHS

VTOL Research, Design and Operation Mwting,

Atlanta, Georgia, Febrnary 17-19, 1969.

7. Andreopoules, J. , Initial Conditions, Rrynolds

Number Effects and the Near Field Charecteris-

tics of the Round Jets

in

a Cross Flow, Juiirnal

of Flight Sciences and Space Research,

Vol.

8 ,

No. 2 ,

March/April

1984,

pp.

118-124.

8. Crabb, D., D. F. G. Dnrzo,

J.

H. Whitelaw, A

Round Jet Normal to a Crossflow, Jouriial of

Fluid Engineering, Transactions of the ASME,

Vol.

103,

March

1981, pp. 142-153.

9. Prandtl, L., Essentials of Fluid Dynamics, pp.

145-149. Blackie

Son

Ltd., London, 1963.

10.

Gordier, R. L., Studies of Fluid Jets Discharging

Into Moving Liquid, St Anthony Falls Hydro

Lab., Univ. of Minnesota, Tech. Paper

N o . 28

Series B, 1959.

11.

McAllister, J . D., A Momentum Theory for the

Effects of Cross Flow on Incompressiblr hrbu-

lent Jets , Ph.D. dissertation, University of Ten-

nessee, 1968.

12.

Reilly,

R. S.,

Investigation of the Deformation

and Penetration of a Turbulent Subsonic Jet

Issuing Transversely into a Uniform, Subsonic

Main Stream, Ph.D. dissertation, University of

Maryland, 1968.

13.

Boldman, D. R., P. F. Brinich and M.

E.

Gold-

stein, Vortex Shedding from a Blunt. Trailing

Edge with Equal and Unequal External Mean

Velocities, Val. 7 5 , part 4 , pp. 721

-

736,

J.

of Fluid Mech.,

1976.

14. Taneda,

S.,

Studies on Wake Vortices:

A n

Ex-

perimental Study on the Structure of a thr

Vor-

tex Street Behind a Circular Cylinder

of

Finite

Length, Reports of Research Institute for Ap-

plied Mechanics, Vol. I, No.

4 ,

Dec.

1952.

16. Sakamoto, H., Vortex Shedding from a Rectan-

gular Prism and a Circular Cylinder Placed Ver-

tically in

a

Turbulent Boundary Layer: Journal

of Fluid Mechanics, Vol.

126,

pp.

147-165, 1983.

16.

Hussain, A.K.M.F. and V. Ramjee, Peri-

odic Wake Behind

a

Circular Cylinder at Low

Reynolds Numbers, Aero. Quarterly, Vol.

27,

pp.

121-142,

May,

1976.

17.

Slaouti, A. and J . H.Gerrard, An Experimental

Investigation of the End Effects on the Wake of a

Circular Cylinder Towed Through Water At Low

Reynolds Numbers, Journal

of

Fluid Mechanics,

Vol. 112, pp. 297-314, 1981.

- 6


8/12

Main Flow /

P

.

. ..

.

R

a)

Peri .odic sp in -o ff vortices

w i t h

w i n g

t i p j e t blo,wi.og.

I:i:;nre 4 .

Nnn-symmetric

j 6 . t i n

CI-oss

f low

o c present s t u d y .

Figure 2 . Wake

f l ow

f i e l d

w i t h

jet

blowing.

..l

7


9/12

0.188

Model

1

Model

2

0.125

0.732

Model

3

Model

4

==- - -pa.

109

1.710

Model

5

A l l

d ime n sion i n i n c h e s

a ) Geometry

of f i v e

j e t e x i t m od el s.

TUNNEL FLOW

(b) Coordinates and yawing angle B .

Figure

5 .

Schematic of experimental

arrangement.

L as er l i g h t s h ee t

.----

J et i n l e t

F ig u r e

6.

The a r rangement o f Laser induce d

f l u o r e s c e n t f l o w v i s u a l i z a t i o n

w

F i g u r e

7 .

Flow in the downstream o f

t h e

i v t

model

4

i n d i c a t i n g

agious

s teady

v ~ r t i c e s ; j / Vm=3. 7 B=30 , Re =240 .

d

I iwre 8.

Surface dye

f l o w

pattern arotmd

i c l

model

3;

V. / V

=

9 . 0 ,

B

=

31,

Ked = 240

.

o f s e c t i o n a l v i e w

o f

j e t p lu me

8


10/12

Figure

9 .

Tile s e c t i o n a l

view

o r

tire

e v o l u t i o n o f j e t stream

i n c r os s f low

on 45 i n c l i n e d p la n e s a t d i s c r e t e

downstream s t a t i o n s ;

V . /V _

= 2.0,

fl =

? O n ,

Red =

4 7 0 ( mdei

3.

I

Counte r rotating j e t v o r t i c e s

OQ /A)

/ / / /

(a) Ver t i ca l . sectional

view

of c i r c u l a r

j e t i n c r o s s f l o w

Lee

side

Major shearing

surface producir,l :

sp i n - u

f f

Degenerated

O @

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