Uncles

HI/02 0057137

NASA Technical Memorandum 4316

Effect of Solidity

and Inclination on

Propeller-Nacelle

Force Coefficients

Garl L. Gentry, Jr., and Dana Morris Dunham

Langley Research Center

Hampton, Virginia

M. A. Takallu

Lockheed Engineering & Sciences Company

Hampton, Virginia

National Aeronautics andSpace Administration

Office of Management

Scientific and Technical

Information Program

1991

Abstract

A series of wind tunnel experiments was emld_tcted to study the effect

of propeller solidity and thrust aa:is inclination o7t, the propeller 7_ormal-

force coeCficient. Ezperiments were cortdueted i_t the Langh'y 14- by

22-Foot Subsonic Tannel with a sting-mmtnted, emznterrotatio_, seal_-

model propeller and nacelle. CoTtfl'guratioT_s had two rows of blades

with combinations of 4 aTtd 8 blades per hub. The solidity was varied

by changing the n_tmber of blades ml. both rows. Tests were conducted

for blade pitch setti,tgs of 31.34 °, 36.34 °, and 41.34 ° over a raT,ge of

a_gle of attack from-10 ° to 90 ° and _ range of advance ratio f_wrl_ 0.8

to 1.4. The inerea.se in pTvpeller normal force with a_gle of attack is

greater for propellers with higher solidity.

Introduction

Although decades of experience exist for propeller

driven aircraft, this experience has been for config-

m'ations having significantly lower power loadings

than those presently being considered. Illvestiga-

tions (refs. 1 through 4) indicated that wing- and

aft-fuselage-recruited advanced turboprot) configura-

tions appear feasible and that configuration selec-

tion depends on fllrther information regarding acous-

tic treatment requirements, structural weight, and

engine-airframe installation a.erodynanlics. This re-

search indicates that one impact of the high disk

loading associated with advanced turboprop installa-

t.ions is increased aircraft stability during operations

which expose the propeller to high inflow angles in

either pitch or yaw. Such operations include the take-

off, (:limb, and approach phases of flight, and ground

operations in crosswinds. These incre_uses in stabil-

ity arc not always beneficial since they may require

higher levels of control to maneuver the aircraft.

The pi'ol)lem of an inclined propeller is one ofmany installation problems that art? related to the

nommiformity of the flow past the blades. A non-uniform inflow can alter vibrational and aeroacous-

tic behavior of the operating propeller. Other exam-

ples of these problems are counterrotating propellers

where the aft. blade row is exposed to a highly non-

mliform wake produced tW the upstream blade row

and pusher configurations where the blades arc ex-

posed to the wake of the upstream wing-pyhm. Nn"

the pusher configurations, because of the asym-metrical variation of the blade section angle of at-

tack, the loads experienced t)3. the blades are cyclic

(ref. 5), and thus the propeller blades experience

time-dependent forces and moments. These cyclic

loads (ref. 6) may cause additional noise (ref. 7) or

vibrational problems (ref. 8). In tim present report,

the focus is on the nommiformity of the inflow caused

by the propeller inclination.

The investigation discussed herein is part of a

broad NASA research program to obtain fim(tamen-

tal aerodynamic information regarding advanced tur-

boprop installation effects. Data from early research

(ref. 9) on lightly loaded propellers showed a strong

dependence of propeller normal force on blade so-

lidity. Also, limited data on more highly loaded

propellers (ref. 10) showed that a comlterrotation

propeller at thrust-axis (nacelle) angles of attack pro-

dueed substantially higher values of normal force

than did a single rotation propeller with the same

solidity. The present inw?stiga.tion was conducted

to extend the research to provide baseline infor-

mation regarding the effect of changing the solid-ity by changing the nmnber of bla(lcs on the fl)re('an(t moment characteristics of an isolated count(w-

rotation turboprop-nacelle combinatioll operating

over a range of angle of attack from -10 ° to 9()° , a

range of advance ratio from 0.8 to 1.4, and at. blade

pitch angles of 31.34 °, 36.34 ° , and 41.34 °. I_'sts were

conducted in the Langley 14- by 22-N)ot Subsonic

Tmmel (ref. 11).

Symbols

al induced velocity fraction in axialdirection

a2 induced velocity fraction in circumfer-ential direction

blade area, ft 2

normal-force coe.fficient,Normal force

qS

Thrust

thrust coefficient

side-force coefficient,Side force

qS

blade section chord, fl.

c,_ se('tioua[ load in normal-force dire('-

Section normal force

tion, _,,2c/2

ct sectional load in thrust direction,Section thrust

;m,'c/2

c u st,etional h)a(1 in side-force direction,Section side force

: O

D t)ropcller dian:eter, t't

.] t)rot)eller advan('¢' ratio, 'n--D

N mmfl)er of blades

n l)rot)elh'r r(}tati{mal st}ee(t, ri)s

q fr{'{'-str{'am (ly/,anfic pr('ssurc, lb/ft 2

DR t)rl)peller radius. _, fI

r distance al(mg prot)(,lhw radius, nor-

malized 1)y l{

S I)ropelh'r disk ar(,a, ft'-'

t t ira(,, sec

l',c |'ree-strealll v(qocity, ft/sec

_,,_ s(,('tion axial initow velocity, ft/se('

_,q section r()lational inflow velocity.

ft/_('c

w scclion vehwity, ft/sec

.r dislalw(' ahmg X-axis. in.

('_ s('('liOll allgl(' 0[' ;:t tat:k. (leg

t_I, lm)p(qh'r in('linat ion (nacclh, allgh" Ofattack), (leg

d hta(h, pit('t_ augle, dog

!t:_.7_, nomimd blade auglc at 11.75/?, dog

1) [l'ce-btl't';t111 density, slugs/ft :1

cr solidity. NI;,/S

0 inth)w angle. (h'/

c' azimuthal position

.Q r(_tati()nal ['r('qu('n('y, rad//s(,( '

Test Apparatus

Propellers

I hol()grat)hs of the t)ropeller-nacelle model used

in this im'(,stigati(m are sh()wll ill tigllres 1 and 2.

The single rotation propeller blade design, designated

SR-2, used for the tests r(,I)orted in reh'rence 1 was

used in counterrotation arrangement for this study

and the on(_ in reference 12. The detailed geome-

try of the SR-2 blade design is documented in refer-

ence 13. In order to sinmlate a representative ratio

of t)ropeller diameter to hub diameter with th(, sin-

gle rotation blades of ref_'rence 13 in a com:t, errot a-

tion arrangement, the SR-2 blade coor(tinat(_s werescaled to a diameter of 15 in. and th(m shifted ra-

dially to accommodate the 111112*requirements. This

resulted in a hub d.iameter of 2.25 in. mM a t)r()pelhw

diameter of 16.1 in. The refer0nc(, ('herd in the orig-inal single rotati()n model (ref. 13) was ]ocate(l atthe 0.75 radial station. For this model, this wf(,renc(,

point was moved to the 0.79 radial station. To ob-

tain the blade t)itch angle at the 0.75 radial station of

the curt(mr configuration, an increment of 1.3,1 ° was

a(hh'd t.o the 0.79 angle setting. Tilt, hubs alh)wed 0,

2, 4, or 8 blades on either or both blade rows. Blad(_

angles were adjusted with a ('(_ltectiv(' pitch-change

gear which p(wmitt(_d a contilluous raI:ge of t)lade

angle setting with an accuracy of _(}.25 <'. The blade

angle used in this im,estigation is th(! average angleof the bla(tes at the 0.75 radial station. For th('se

tests, both })lad(' rows of the c()miterrotation systcn:

were set at the same pitc]l setting. The spacing; })e-

tween th(' pitch-chang(, axis of the blade rows was

2.31 in. (().287R). The front row of blades was drivencouutvrch)ckwise ]o_)king upstream. The couutor-

rotatioIl g('ar])ox (:ollsist('(1 of two gt'a,l'S ;Ilia t.wo [)it:-

ions which (h'ovc the I'('ar blade r()w at ill(, sam(, Sl)('(,(t

t)111 in the direction opposite to I hal ()f Ill(, front t)la(h'I'(IW.

Nacelle and Support System

Tim dimensional eharacteristi('s of the prot)(qter-

nacelle at'(, given ill tables 1 and 2 and are shown in

figure 3. The nacelh' used ill this investigation was a

})ody of revolulion with maximmn outsidv diameter()f 6 in. and housed a water-(:ooled electri(: motor

which was rate(t at 29 hi)at l()000 rl)m. A fairing

which c()v('r(,d the co:mt('rrotati(m gearl)ox smoothlytransitioned from tho huh diameter t() dw nac(qh'

diameter. The na('clh, was m(mnt('d as a straight

extension of a straight sting.

Facility

Tests were (:ondu(:ted in the Langley 14- by 22-Foot Subsonic Tmmel. which has a test seeti(m

14.50 ft high by 21.75 ft wi(h ,. This is a ('lose(t-

circuit atmospheric wiu(l tmmel and is des(:ril)('d inrefer(m(:(_ 11. Th(_ naeelh_ was mounted (m a model

2

supportcartshownin figure4whichallowedthena-celle to be rotated to different angles of attack and

sideslip while remaining at the tunnel centerline tominimize wall interference effects.

Test Conditions

Data were obtained at a free-stream dynamic

pressure of 4.5 psf, which represents a tunnel speed

of 63 fps. The free-stream velocity of 63 fps was cho-

sen to give an advance ratio in the range from 0.8 to

0.9 for the 8- by &blade propeller at the maximum

available power from the electric motor. The corre-sponding dynamic pressure of 4.5 psf was then used

for all the propeller configurations. Propeller operat-

ing conditions were selected by first sctting the tun-

nel dynamic pressure and then setting advance ratio

using propeller rotational speed (rpm). These con-

ditions were held constant throughout a given sweep

of angle of attack or sideslip. Aerodynamic forces

and moments were measured with a six-component

strain-gauge balance located inside the nacelle with

the balance moment center as indicated in figure 3.

All data presented are time averaged and were ac-

quired at a rate of 20 samples/sec for 5 sec.

Results and Discussion

The theoretical relations and definitions between

the inclination angle C_p, solidity _, and the time-averaged coefficients of thrust CT, normal force CN,

and side force Cy are briefly discussed in the ap-

pendix. The data are presented for the combined

propeller-nacelle configuration in terms of the time-

averaged coefficients. First, data are presented forthe entire angle-of-attack range from -10 ° to 90 ° for

the 8- by 8- (8 blades in front row and 8 blades in

second row) and 4- by 4-blade propellers for threedifferent advance ratios to illustrate the variation of

thrust and normal force due to the propeller inclina-tion. Then, data are presented for selected angles of

attack as a function of advance ratio for the 8- by 8-,

8- by 4-, and 4- by 4-blade propellers. Finally, data

are presented as a function of solidity.

Figures 5 and 6 show the variation of thrust and

normal-force coefficients as a flmction of propeller in-

clination ap, for different values of propeller advanceratio. The data in figure 5 for the 8- by 8-blade

configuration, which has a solidity of 0.56, indicatethat, for a constant rotational speed, both thrust and

normal-force coefficients increase in magnitude as apincreases. Thrust coefficient remains nearly constant

between ap = -10 ° and 10 ° and then begins to in-

crease as C_pincreases, although the rate of increase isdependent on advance ratio. Normal-force coefficient

is also dependent on advance ratio with CN increas-

ing more rapidly for decreasing advance ratio. In an

examination of the data for all three advance ratios,

the increase in CN seems to be nearly linear over the

range of (_v up to approximately 60 ° after which therate of change begins to decrease. Similar trends are

observed in figure 6 for the 4- by 4-blade configura-

tion with solidity of 0.28. For the lower solidity, the

linear range for C N seems to be somewhat smaller.

A comparison of the normal-force coefficients in fig-

ures 5(b) and 6(b) shows that at a constant advance

ratio a higher maximum value for C N is obtained for

the propeller with higher solidity. Further analysis

of the data is restricted to the linear range (C_p = 0°

to 30°).

Figures 7, 8, and 9 show the variation of Cy, CT,

and C N as a function of propeller advance ratio J,

for various values of C_p for the 8- by 8- (0 = 0.56),the 8- by 4- (a = 0.42), and the 4- by 4- (a = 0.28)

blade configurations, respectively. For all these con-

figurations, at these blade angles the thrust coeffi-

cient decreases with increasing advance ratio (lower

loading). This decrease in thrust coefficient has a

steeper slope for the highest propeller solidity. The

normal- and side-force coefficients are very small for

ap = 0 °. For all solidities, normal-force coefficientshowed nmch more sensitivity than the other coeffi-

cients to changes in ap and J, as would be expected.

Better insight into the sensitivity to solidity

changes can be gained by presenting the force co-efficients as a function of the advance ratio for dif-

ferent values of solidity on a single figure, as shown

in figure 10 for ap = 0° and 20 ° . As expected, thenormal-force coefficient remains small for all values

of propeller solidity when c_p = 0 °. The increase inthe level of CN with higher solidity is evident in the

data for ap = 20 °.

Figure 11 illustrates the variation of Cy, CT,

and C N with respect to propeller solidity for vari-

ous values of c_p. The blade pitch at the 0.75 ra-dial station was 41.34 ° and the advance ratio

was 1.1. As c_v increases, the level of normal force in-creases. Normal-force coefficient also increases with

increasing solidity. The magnitude of this change

is more pronounced at higher nacelle angles of at-

tack. Although the side force for all angles of attack

is expected to remain 0 for a counterrotation system,the data show nonzero side force. Thrust coefficient

also increases with increasing solidity; however, its

increase is not as pronounced with increasing nacelleangle of attack as that of the normal-force coefficient.

The results shown in figures 12 and 13 are for

lower advance ratios, J = 1.0 and 0.9, respectively.

3

Althoughthesecasesrepresenthigherloadingthanthecaseshownin figure11,similartrendsin thedatamaybeseen.The increasein solidityand nacelleangleof attackresultsin an increasein the levelofCN. To illustrate the combined effects of solidity and

advance ratio more clearly, tile variation of C\, withrespect to _ for the three different advance ratios at

c_ = 20 ° is shown in figure 14. The higher loaded

conditions result in a higher normal-force coefficientfor a given solidity.

Summary of Results

A wind tunnel investigation has been conducted

with a counterrotation propeller with SR-2 blades

operated with 4 and 8 blades per hub to vary solidity.

For a propeller with the thrust axis at an angle of

attack, the results may be summarized as follows:

1. The normal force associated with nonzero an-

gles of attack increases linearly at lower angles of at-

tack but the rate of increase decreases after an angleof attack of 30 ° .

2. Tim level of normal force is higher for pro-pellers with higher solidity and for higher thrust op-erating conditions.

3. Increasing the numl)er of blades in the front

row (from 4 by 4 to 8 by 4) is more effective at in-

creasing thrust than increasing the number of blades

in the back row (from 8 by 4 to 8 by 8).

NASA Langley Research CenterHampton, VA 23665-5225November 22, 1991

4

AppendixTheoretical Relations and Definitions ofVarious Parameters

Accordingto strip theory,for thepropelleraxisat anangleof attackof 0°, the section lift and dragforces remain constant with the blade azimuthal po-

sition. The section angle of attack is only influenced

by the induced velocities due to helical velocity vec-

tor. However, the section lift and drag coefficientsare dependent on the section angle of attack and the

section velocity which are defined as

c_ =/3- _b (1)

andVq._ - (2)

COS

where/7 indicates the section pitch angle with respect

to the plane of rotation. In equation (2), Vq and0 are the circumferential velocity and helical angle,

respectively, and are defined below. As illustrated in

figure 15, Va is defined as the axial velocity and is

assumed to vary from tile free-stream velocity by a

fraction of V_c as

va = V_c(l + al) (3)

In the same manner, yq is defined as circumferentialvelocity and is assumed to differ from the rotational

velocity rft by a fraction a2 as

Vq=r_(1-a2) (4)

In equation (4), r is defined as the radial station alongthe blade and f_ is the propeller rotational speed.

Finally, ¢ becomes

¢ = tan_ 1 v_a (5)Vq

In reference 14, it is shown that induced velocity

fractions a 1 and a2 can be obtained from balancing

the linear and angular momenta around the propeller

and its wake. The resulting expressions found for a 1

and a2 are related to the circulation distribution in

the radial direction and propeller solidity a where

NB- (6)

S

The sectional lift and drag then define the thrust

and torque coefficients, whereas normal and side

forces vanish throughout the cycle due to symmetric

loading.

Once the propeller axis is set at an inclination

to the incoming flow, both axial and circumferential

velocities Va and Vq must be modified for the propeller

inclination c_p as follows:

Va= (1 + al)VaccOS_p (7)

Vq = (rFt + Vz_ sin c_p cos g,) (1 - a2) (8)

Consequently, the inflow angle 0 and angle of

attack c_ vary with azinmthal position W. This vari-ation is illustrated in the sketches in figure 16. Sec-

tional lift and drag become hmctions of azimuthal

position and the thrust axis inclination. Thus, thesectional force coefficients in the plane of rotation

such as sectional normal-force coefficient cr, and sec-

tional side-force coefficient c.v become

ct = f (c_p, _), rgL V_, _)

c,, = f (Ctp, tO, r[_, V._c, a)

c,v = f (c_p, tl_,,rFt, Vx, or)

(9)

(10)

(11)

In theoretical calculations, the instantaneous pro-

peller force coefficients are computed from the in-

tegration of distributed loads along each blade in theradial direction so that

Cr(t) = f (c_p,.],_)

Cx(t) = f (",,, s, #)

cy(t) = f (Ctp,.I,_)

(12)

(la)

(14)

For 0° inclination, the time-averaged values of totalnormal and side forces should remain zero. For the

propeller at some angle of attack, the time-averagedvalues of these forces are the mean value over a full

propeller blade cycle and are

CT = f (c_p,J, _) (15)

CN = f (_p, J, o) (16)

Cy = f (ap, J,a) (17)

The expressions in equations (15) through (17) cor-respond to the experimental results presented in the

main body of this report.

5

References

1. Applin, Zachary T.; and Coe, Paul L., Jr.: Low-Speed

Stability and Control Characteristics of a Transport Model

With Aft-Fuselage-Mounted Advanced Turboprops. NASA

TP-2535, 1986.

2. Coe, Paul L., Jr.; Applin, Zachary T.; and Williams,

Louis J.: Stability and Control Results for Advanced

Turboprop Aft-Mount Installations. SAE 1984 Trans-

actions, Volume 93, Soc. of Automotive Engineers, Inc.,

c.1985, pp. 6.256 6.263. (Available as SAE Paper

841479.)

3. Ridder, Sven-Olof: Wind Tunnel Test of a Twin, Rear

Propeller Transport Aircraft Configuration at Low

Speeds. ICAS Proceedings 1984--14th Congress of the

International Council of the Aeronautical Sciences, Vol-

ume 2, B. Laschka and R. Staufenbiel, eds., International

Council of Aeronautical Sciences, c.1984, pp. 644-654.

(Available as ICAS-84-2.6.3.)

4. Aljabri, A. S.: Wind Tunnel Tests on a One-Foot Di-

ameter SR-7L Propfan Model. AIAA-87-1892, June-July

1987.

5. Takallu, M. A.: Unsteady Potential Flow Past a Propeller

Blade Section. NASA CR-4307, 1990.

6. Takallu, M. A.; and Spence, P. L.: Prediction of Unsteady

Thrust and Torque Coefficients for a Pusher Propeller.

AIAA-87-2630, Aug. 1987.

7. Takallu, M. A.; and Block, P. J. W.: Prediction of Added

Noise Due to the Effect of Unsteady Flow on Pusher

Propellers. AIAA-87-0255, Jan. 1987.

8.

9.

10.

11.

12.

Martinez, Rudolph: Predictions of Unsteady Wing and

Pylon Forces Caused by Propeller Installation. NASA

CR-178298, 1987.

Ribner, Herbert S.: Formulas ]or Propellers in Yaw and

Charts of the Side-Force Derivative. NACA Rep. 819,

1945. (Supersedes NACA ARR 3E19.)

Dunham, Dana Morris; Gentry, Garl L., Jr.; and Coe,

Paul L., Jr.: Low-Speed Wind- Tunnel Tests of Single- and

Counter-Rotation Propellers. NASA TM-87656, 1986.

Gentry, Garl L., Jr.; Quinto, P. Frank; Gatlin, Gre-

gory M.; and Applin, Zachary T.: The Langley 13- by

22-Foot Subsonic Tunnel: Description, Flow Characteris-

tics, and Guide for Users. NASA TP-3008, 1990.

Dunham, Dana Morris; and Gentry, Garl L., Jr.: The

Effect of Solidity on Propeller Normal Force. SAE

1989 Transactions--Journal of Aerospace, Section l--

Volume 98, 1989, pp. 1232 1237. (Available as SAE Paper

892205.)

13. Jeracki, Robert J.; Mikkelson, Daniel C.; and Blaha,

Bernard J.: Wind Tunnel Performance of Four Energy

Efficient Propellers Designed for Mach 0.8 Cruise. NASA

TM-79124, 1979. (Available as SAE Paper 790573.)

14. Takallu, M. A.; and Dunham, Dana Morris: A Hy-

brid Method for Prediction of Propeller Performance.

AIAA-90-0440, Jan. 1990.

6

Table 1. Dimensional Characteristics

Counterrotation propeller diameter, in ............. 16.10

Spacing between blade row, in ................. 2.30

Hub diameter, in ....................... 4.50

Maximum nacelle diameter, in ................. 6.00Distance of moment reference center aft of

forward propeller disk, in .................. 38.24

Table 2. Nacelle Coordinates

x, in. r, in. x, in. r, in.

0.000

0.028

0.528

1.028

1.528

2.028

2.528

3.028

3.5284.028

4.528

4.778

9.248

9.91810.618

11.068

11.628

12.258

12.628

12.645

0.000

0.149

0.525

0.857

1.140

1.405

1.638

1.8452.015

2.145

2.235

2.250

2.250

2.3332.545

2.685

2.840

2.935

2.970

2.976

12.766

12.904

13.180

34.028

36.028

37.028

38.02839.028

40.028

41.028

42.028

43.028

43.74544.028

45.028

46.028

47.028

48.028

49.028

49.345

2.982

2.986

3.000

3.000

2.9402.900

2.850

2.520

2.300

2.160

2.020

1.920

1.8311.820

1.750

1.680

1.620

1.600

1.560

1.550

7

ORI'3[N/_ !. T.,_,:7_i"

BLACK AND WHITE Fr-i_;_C_r_/_.'.,-'r,

Figure 1. Propeller-nacelle model mounted for tests.

L-91-14546

Figure 2. Close-up of 8- by 8-blade propeller.

L-91-14547

16.1 _

5.91

'k

1-,c 38.24 - I FBalanc e

l I / moment

I/ center

---o---j-----

2.31

Figure 3. Sketch of propeller-nacelle model. Linear dimensions are in inches.

L-91-14549

Figure 4. Mounting arrangement of propeller-nacelle model in Langley 14- by 22-Foot Subsonic Tunnel.

BLACK AND WH!I-E !:/,,-_:;:2RAPh

2.0

CT

1.0

-1.0-20

J

0 o.8

[] i.o

1.2

2O 4O 6O

(a) Thrust coefficient.I

8O

_p, deg

100

C N

4.0

3.0

2.0

1.0

-1.0

/

[]

>-- - 'a

0 0.8

[] 1.0

1.2 (b) Normal-force coefficient.I

-20 0 20 40 60 80

Ctp, deg

Figure 5. Effect of power on thrust and normal-force coefficients for 8- by 8-blade propeller.

a -- 0.56; q = 4.5 psf.

100

/30.75 = 36.34°;

10

CT

2.0

1.0

13-- --[3-- -- - -

J

00.B

[] 1.0

i

(a) Thrust coefficient.I

8O-1.0

-20 0 20 40 60 100

,degP

CN

4.0

3.0

2.0

1.0

J

0 o.8

[] 1.0

(b) Normal-force coefficient.-1.0

-20 0 20 40 60 80 1O0

(z , degP

Figure 6. Effect of power on thrust and normal-force coefficients for 4- by 4-blade propeller. _0.75 = 36-3_1°;

= 0.28; and q = 4.5 psf.

11

Cy

C T

.4

-.4

2.0

1.6

1.2

.8

.4

L.]. z.-k

0.7 .9 1.1 1.3

J

C N

2.0

1.6

1.2

.8

.4

0.5 .7 .9

ap, deg

0 0

[] 10

O' 20

30

<x.\

) ;..k.

"/_ Z

>"-0....<>.

21- _-E]..., "

"A

"E],, 0

3----01.1 .3 1.5

J

Figure 7. Effect of nacelle angle of attack oll propeller thrust coefficient and acrodynamic forces for 8- by8-blade propeller. 3o.75 = 41.34°; c_ = 0.56.

12

Cy

CT

.4

-.4

2.0

1.6

1.2

.8

.4

0.7 .9

,%[]

CN

2.0

1.6

1.2

.8

.4

_Z

O_p,deg

O 0

['1 10

O 20

A 30

El......[

0.1 1.3 1.5 .7 .9

>.

.1

J J

,,,_.

]- - ..,....

"FI'_'[ZIZ ]

o-o.3 1.5

Figure 8. Effect of nacelle angle of attack on propeller thrust coefficient and aerodynalnie forces fi)r 8- by4-blade propeller. /30.75 = 41.34°; a = 0.42.

13

.4

Cy 0

-.4

_p, deg

O 0

[] 10

O 2O

Z_ 30

CT

2.0

1.6

1.2

.8

.4

0.7 .9

CN

1.8

1.4

1.0

.6

.2

-.2.7

Z_

O----£

X

-'1-_E]_. _D.....£]

1.1 .3 .5 .9 .1 1.3 1.5

J J

Figure 9. Effect of nacelle angle of attack on propeller thrust coefficient and aerodynamic forces for 4- by4-blade propeller. L30.75= 41.34°; a = 0.28.

14

CT

1.6

1.4

1.2-

1.0-

.8

.6.8

I 1 I

•g 1.0 1.1

J

.8

.6-

.4-

C N

.2

1.2 .8

(a) c, = 0°

Configuration

0 0.28 4 by 4 blades

[] 0.42 8 by 4 blades

0.56 8 by 8 blades

I I I

.9 1.0 1.1

J

I

1.2

CT

1.6 --

1.4

1.2

1.0-

.8

,6.8

Configuration

0 0.28 4 by 4 blades

[] 0.42 8 by 4 blades

0.56 8 by 8 blades

0----...

CN

1.6

1.4

1,2

1.0

.8

I I I I .6 I I t.9 1.0 1.1 1.2 .8 .9 1.0 1.1

(b) _ = 20%

Figure 10. Effect of advance ratio on thrust and normal-_)rce cocfl=icients._l).75 = 41.34 o.

J

1.2

15

.5-

Cy

-.5 I I I

C T

B

1 m

0 I I I I

_p, deg

Oo

[] 10

O 2o

A 30

m

C N

0 Or-'--- © -O_

-.1 I I I I.2 .3 .4 .5 .6

(f

Figure 11. Effect of nacelle angle of attack on side-force, thrust, and nornml-forcc coefficients as function ofpropeller solidity. _.75 = 41.34°; J = 1.1.

16

.5-

Cy

-.5 I II ,J

C T

_

_

0I I I I

O_p,deg

Oo

[] 10

0 20

/k 30

C N

_

C_7_

I I I I-'1.2 .3 .4 .5 .6

function ofand normal-force coefficients as

Figure 12. Effect of nacelle angle of attack on side-force, thrust,

propeller solidity. _0.75 = 41.34°; J = 1.0.

17

.5-

Cy

".5 I I I

CT

_

1 -

0 I I I I

_p, deg

Oo

[] 10

0 2o

30

CN

2

_.---------0 {3

0_/ 0 --0--

-.1 I I I I

.2 .3 .4 .5 .6

(t

Figure 13. Effect of nacelle angle of attack on side-force, thrust, and normal-force coefficients as function ofpropeller solidity. ,_0.75 -- 41.34°; J = 0.9.

18

C N

1.6

1.4_

1.2_

1.0_

.8

.6

.2

0 0.9

[] _.o

1.1

I I I I.3 .4 .5 .6

Fig, ure 14. Eft'cot. of adv_mcc ratio oil norma.l-forcc coefficient, as t'unct.ion o[ 14ado solidily.

r_:l, = 20°.

,4 °_4().77,= 41.3 :

19

dL

Plane _k

of rotati__

Zero lift line _ _//" _

dT _ _",_ _[_ /"Va\

V AV iIq q_

' -- rD! I

Figure 15. Forces on blade sectkm without propeller inclhmtion.

Voosin o_P

Cy

CT

J

C N ct

Voocos O_p

Downgoing blade

Voo sin C_p-_ _ cos ep

/

Upgoing blade

Figure 16. Forces on blade section wit, h propeller inclination.

2O

REPORT DOCUMENTATION PAGEForm Approved

OMB No 0704-0188

h_bhc reporting burderl for this collection of information is esthnated to average I hour per response, including the time for reviewing instructions _earchillg existing data sources.galherin_ and mamtamirlg the data needed, and completing and reviewing the collection of information Send comments regarding th_s burden estimate or any other aspect of thiscollection of information, mchJdmg suggestions for reducing this burdei_ to Washington Headquarters Services, Directorate for Inlormatiorl Operations and Reports, 12].5 JeffersonDaws Highway, Suite 1204 Arlington VA 22202 4302, and to the Ofhce of Management and Budget, Paperwork Reduction ProJect (0704 0188), Washington, DC 20503

1. AGENCY USE ONLY(Leave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED

D(,ccnllmr 1991 "l_,chnical Menlt_ran(lum

4. TITLE AND SUBTITLE

Elfoct _4' Solitlity and(%of licit,hiS

Inclination on Propellcr-Nacdlo Force

6. AUTHOR(S)

(',arl I,. (;entry, ,h'.. Dana Morris bunham, and M. A. Takallu

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

NA£A Langley Research Center

] ]_lltli)l(tll. VA 23(;65-5225

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

Nat iomJl At'rttnaut its and Spacc AtlmilJisl ration

\\'ashinglltJl. D(' 20,546-0()01

5. FUNDING NUMBERS

WI! 535-03-10-02

8. PERFORMING ORGANIZATION

REPORT NUMBER

L- 1[i93:1

1O. SPONSORING/MONITORING

AGENCY REPORT NUMBER

NASA rl_M-4316

11. SUPPLEMENTARY NOTES

(;('ntry and DmlhanJ: l,angh,y I{esear('h (_cnter, Hampton, VA; Takallu:

Co., [[aIJlpton, VA.

l_ockhecd EngiIJct,ring £: Sciences

12a. DISTRIBUTION/AVAILABILITY STATEMENT

t TnJ'hlssiIied [!nlintih,d

S_ll)jp'<'l (!aleg _') 0'2

]2b. DISTRIBUTION CODE

13. ABSTRACT (Maximum 200 words)

A s('ries of wintl Iilllll(_l oxi)t,I'illl(,llts was (',)II(]llcte(] to Stlldy tile eff(,ct of l)ropelh,r solidity and thrllst axis

inctinatitlti (m tlJo l)ropellcr IJtJrntal-t'ttrce ('ocfli('i0nt. EXlJJ'rimelJts were (!OlldU('t.t!tt ill tilt! Langh'v 14- by 22-b_ot

,qltltsonic TllllllCi wit]l a st ing-mounled, (tt)llllt.errol.atioll, scale-zllOd('] propetlt,r and nacelle. Configm'atitJnS had

two rttws of 1JlatIcs with coiJJI)inatiJJnS of 4 aml 8 blades per hub. The solidity was varied by changing the

mlml_t,r of blades on both rows. "l_sLs were conducted for blade pitch settings of 31.34 °, :IG.:H °, and 41.34 °

()V(q" _1. l'&Ilg(' Of _-tIlgl(_ (If attack fronl -l(I ° to 90 ° and a range of adwmce ralio from (I.S I(t 1.4. Tht, int'rcasc ill

tJropelh,r ut)rlJJal ft)rtv with ;u@v of attack is g, roater f<,n' prtJpellers with higher solidity.

14. SUBJECT TERMS

Turboprop: Countvrrotatiou propel[ors: Rlade solidity: High anglo of m tack

17. SECURITY CLASSIFICATION

OF REPORT

Unclassitied

_ISN 7540-01-280-S500

18. SECURITY CLASSIFICATION

OF THIS PAGE

Unclassified

19. SECURITY CLASSIFICATION

OF ABSTRACT

15. NUMBER OF PAGES

21

16. PRICE CODE

A();3

20. LIMITATION

OF ABSTRACT

Standard Form 298(Rev. 2-89)Prescribedby ANS_ Std Z39-18298 102

NASA-Langley 1991