AIM-92-3779 Wind Tunnel Performance Results of Swiri Recovery Vanes as Tested with an Advanced High Speed Propeller J.A. Gazzaniga Sverdrup Technology, Inc. Lewis Research Center Group Brook Park, OH

G.E. Rose National Aeronautics and Space Administration Lewis Research Center Cleveland, OH

AI A AIS A E l AS M El AS E E 28th Joint Propulsion

Conference and Exhibit Julv 6-8, 1992 / Nashville, TN

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For permlsslon lo copy or republish, contact the American Institute of Aeronautics and Astronautics 370 L'Enfant Promenade, S.W., Washington. D.C. 20024

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WIND TUNNEL PERFORMANCE RESULTS OF SWIRL FECOVERY VANES AS TESTED WITH AN ADVANCED HIGH SPEED PROPELLER

John A. Gazzanixa Sverdrup Technology, Inc.

Lewis Research Center Gmup Bmok Park, Ohio 44142

Gayle E. Rose’ National Aeronautics and Space Adminiitration

Lewis Research Center Cleveland, Ohio 44135

Abstract

Tests of swirl recovery vanes designed for use in conjunction with advanced high speed propellers were carried out at the NASA Lewis Research Center. The eight bladed 62.23 cm (24.5 in) vanes were tested with a 62.23 cm (24.5 in) SR-7A high speed propeller in the NASA Lewis 2.44 x 1.83 m (8 x 6 ft) Super- sonic Wind Tunnel for Mach number range of 0.60 to 0:80. At the design operating condition for cruise of Mach 0.80 at an advance ratio of 3.26 the vane contribution to the total efficiency approached 2 percent. At lower offdesign Mach numbers the vane efficiency is even higher approaching 4.5 percent for the Mach 0.60 con- dition. Use of the swirl recovery vanes essen- tially shifts the peak of the high speed propeller efficiency to a higher operating speed. This allows a greater degree of freedom in the selec- tion of RPM over a wider operating range. Another unique result of the swirl recovery vane configuration is their essentially constant torque split between the propeller and the swirl vanes over a wide range of operating conditions for the design vane angle.

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Introduction

For almost half a century propellers were the dominant form of aerial propulsion. Jet propul- sion, beginning with turbojets and evolving into turbofans, rapidly assumed dominance in aerial propulsion especially in the area of civil trans-

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port. With a resurgence of interest in high speed propellers for improved fuel savings in the mid-l970’s, theoretical and experimental studies were carried out by both NASA and industry which indicated an improved efficiency of opera- tion at high transonic cruise Mach numbers over conventional turbofans and turbojets.’,2 In addi- tion to efficiency increases exhibited by single rotation propellers or propfans, as they came to be called, counter-rotating propfans showed an even higher efficiency due to the ability of the second rotating stage to recover swirl present in the propeller slipstream that would ordinarily be considered a part of the single-rotation propeller loss mechanism.) If the second rotating stage were instead a fixed row of vanes, it may be possible to recover a substantial portion of the swirl without the complexity of a second rotating stage.

To determine the effectiveness of the swirl revovery vanes in generating propulsive thrust an experimental investigation was carried out which tested scaled swirl recovery vanes at cruise Mach number conditions in the NASA Lewis 2.44 x 1.83 m (8 x 6 ft) Supersonic Wind Tunnel. This was done utilizing the Lewis propeller test rig running with aeroelastically scaled SRJA high speed propellers (Fig. 1). Vane angle was varied to investigate the opti- mum vane angle at cruise. In addition, Different blade angles were tested to observe the effects of different power absorbtion and the generation of swirl upon the vane performance. Also, the

‘Caylc Rou is currently cmploycd at the Bcclon Dicki-n Rcssarch Ccnlcr of Rcwarch Triangle Park. NC.

?his paper is declared a work of the U.S.Govcmmcrusml is MI sub- jeci 10 copyright pmtcctiun in the United Statcs.

effect of spacing between the rotor and the vanes was investigated by moving the vanes 16.38 cm (6.45 in) aft of the nominal forward position.

Aerodvnamic Desien Conceots

To have the swirl recovery vanes perform at their optimum, various aerodynamic and struc- tural design parameters and limitations were con- sidered in their design. The primary objective of the swirl recovery vanes is to generate propul- sive thrust from the residual swirl present in the propeller slipstream while the vanes are operat- ing in the same transonic speed regime as the high speed propellers. This would indicate that the benefits of sweep that accrue with wings and high speed propellers would also apply to the swirl vanes. Since the swirl vane is non-rotating the vane would require a low amount of twist. The torque produced on the vane is directly related to the activity factor of the vane plan- form. In addition, flutter considerations might lead to a change in the structural characteristics of the swirl vanes. To design the swirl recovery vanes various computer design codes were used in a manner similar to that for the design of high speed propellers'. A compressible streamline curvature computer code was used to determine the velocity flowfield at the propeller and the swirl vanes. To determine performance, load- ing, and geometry of the swirl vane a lifting line induction method based on the principles of Goldstein' was used. Once convergence was ob- tained between the rotor and vane induced veloc- ity components the vane was then evaluated for possible choking between the vanes again using the compressible streamline code. For determi- nation of the inboard vane geometry (r/R S 0.55) a two dimensional Euler code was used, treating this vane region as a transonic airfoil cascade. The initial swirl vane design consisted of twelve vanes, however, flutter analysis indi- cated that flutter may occur within the experime- nt's Mach number range. To alleviate the possi- bility of flutter an eight vane design was chosen that has a higher planform activity factor to compensate for lower number of vanes.

Aooaratus

Sunersonic Wind Tunnel

The swirl recovery vane model tests were carried out in the NASA Lewis 2.44 x 1.83 m (8 x 6 ft) Supersonic Wind Tunnel. The test sec- tion of the tunnel consists of a 4.27 m (14 ft) perforated area of 5.8 percent porosity? The tunnel porosity provides an environment where interactions between the model and the test sec- tion walls can be minimized during testing in the transonic/supersonic speed regimes. Testing of the swirl recovery vanes was carried out for a Mach number range of 0.45 to 0.80 with the tunnel run in the open circuit propulsion mode where outside air is supplied upstream of the model and is subsequently exhausted after pass- ing through the test section.

Proneller Test Rig

The Lewis Single Rotation Propeller Test Rig (SR/PTR) was modified for carriage of the swirl recovery vanes. The SRIPTR is powered by a three stage air turbine that can provide up to 746 kw (loo0 hp) of power to the model when supplied with 366" K (660" R) heated air delivered at 3.1 x 106 Newtons/m* (450 psi). The rotor section of the model incorporates a rotating balance that measures thrust and torque of the propeller blades and the spinner. A rotat- ing transformer is utilized to carry the balance signals off of the rotating shaft. To measure the thrust and torque of the swirl recovery vanes a stationary balance is used. Both the rotating and the stationary vane balances were statically calibrated before and after the test. Reference drag runs were performed to determine the body drag, spinner drag, and vane hub drag tares to correct the performance data.

Additional hardware which was used to con- vert the SRlPTR into the swirl recovery vane (SRV) configuration included an adapter, spacer, stationary balance, snubber system, and a na- celle. A schematic of the SRV rig for both the fore and aft vane configurations is illustrated in Figure 2.

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W'

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W

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L.

The afterbody for both vane positions is of a constant circular cross section. The stationary balance for the swirl recovery vanes was mount- ed on the modified section of the SWPTR through hke use of tke &pier. The swir: vane hub is attached to the balance cantilever fashion which, for the forward vane position, is attached to a spacer. Removal of the spacer allows for the vane hub and balance to be moved rearward 16.38 cm (6.45 in) to investigate the interaction effects between the rotor and swirl recovery V a n e s .

The vane balance consisted of a cylindrical body with instrumented torque and thrust flex- ures. Due to the balance being relatively flexi- ble at the thrust section of the balance, excessive mode vibrations were experienced at particular rig operating speeds. Strain gages were mounted on the balance for safety monitoring. In addi- tion, a snubber system was designed which, when engaged, would damp out balance vibra- tions. As vane balance data cannot be taken when the snubbers are engaged the snubbers were designed as retractable pistons which could be actuated from the wind tunnel control room. Also, the snubbers would automatically engage when balance strain gage signals exceeded ac- ceptable limits in addition to being engaged and disengaged manually when deemed necessary.

Swirl Recoverv Vanq

The swirl recovery vanes consist of eight highly swept vanes which incorporate a linear taper from hub to tip with a resulting activity factor of 174 for the 62.23 cm (24.5 in) diame- ter vanes. NACA 16-series airfoil sections are used exclusively in the vane planform which exhibits approximately 5" of twist along the length of the vane. The vanes are fabricated from 4340 alloy steel and are each attached to the hub by four screws. A gear is incorporated into the vane hub to allow simultaneous changes in pitch of all the vanes over a range of 10 degrees in .W increments. This allows for investigations into the effect of vane angle chan- ges upon efficiency. Pertinent features of the SRV geometry are shown in Table I with the

planform characteristics of the swirl recovery vanes as tested illustrated in Figure 3.

Before performance testing began. flutter clearance tats of the vanes were done. No evi- dence of flutter was found, however several forced excitation modes were found to exist in the operating range of the SWF'TR. Throughout the test, strain gages were mounted on at least one of the stator vanes for safety monitoring. The SR/pTR would automatically shutdown when the strain gage signals exceeded acceptable limits. Previous propeller tests have documented a slight reduction in propeller efficiency due to the installation of strain gages on propeller blades.' It was not possible to test the vanes without the strain gages installed, therefore no corrections were made to the efficiency for the effect of strain gages.

With the vane hub mounted directly to the vane balance, any surface drag produced by the vane hub would be measured as a loss in vane thrust. During reference drag runs, vane hub aerodynamic drag tares were obtained with the blade holes in the vane hub taped over. When the vanes were mounted on the vane hub the retaining screw access cavities were left open, Almost all of the testing was done with these cavities left open. Three runs were made with these cavities taped over in order to see if a reduction in drag was noticable with a smooth vane hub. Two of these runs were made with the vanes in the forward vane configuration and the other was made in the aft vane configuration. Results show a loss in the vane thrust of 3.96 kg (1.8 Ibs) at Mach 0.8 and 1.32 kg (0.6 Ibs) at Mach 0.6. Dependence on forward or aft vane configuration was not evident. A correction based on the data was made and was applied to the vane performance calculations.

SR-7A ProDeller

The eight blade high speed propellers are of SRJA design. An activity factor of 227 is pres- sent with this planform. The original swirl re- covery vane design was to incorporate SR-3 propellers for the rotor, however due to vibra- tion problems with the SR-3 blades the SR-7A

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Four rows of 10 pressures were located along W the nacelle at four circumferential locations spaced 90 degrees apart qable 111). These nacelle pressures were used to calculate the mcelle pressure drag tare. Body pressures located on the balance and spacer were measured in order to complete the plotting of the pressure distribution around the model but were not in- cluded in the calculations due to the constant circular area cross sections they were located at. The axial location of these pressures was depen- dent on vane configuration. Table N gives both forward and aft vane configuration coordinates for these pressures. A total of 24 pressures were recorded at 3 different radial locations within the rotor cavity pable V). These pres- sures were used to calculate the pressure area force acting on the downstream face of the rotor. Pressures in the cavities upstream (12 taps) and downstream (8 taps) of the vane hub were also recorded. The axial location of the pressures was also dependent on vane configuration Fable VI). These pressures were used to calculate the pressure area force acting on each face of the vane hub.

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propeller blades were used instead. The primary difference between SR-3 and SR-7A is the latter propeller blade being formed out of carbon com- posites as opposed to titanium for the former.' The relatively light composite construction of t i e SR-7A alleviated the vibration problems but due to a 15 percent lower design power than the SR- 3, the SR-7A propeller was required to operate far above its design condition for the swirl re- covery vane test and this increased loading re- sulted in different propeller blade deflections than originally intended. The SR-7A design characteristics are shown in Table 11. Blade planform parameters for the original SR-7A design point (C, = 1.45, J = 3.06) are shown in Figure 4.7

The blade angle of the SR-7A was set with a gear and pin mechanism which, like the swirl recovery vanes, allows simultaneous pitch angle adjustment. By using this mechanism it is possi- ble to adjust the blade pitch in 2.88" increments. Due to the retention method used for the propel- ler blades a small amount of play exists that includes any lash which might be present be- tween the adjusting gear and the gear on the blade shank. Data obtained during this experi- ment suggest that the propeller blades would change up to 0.2" during a run in a consistent direction which would corroborate the effect of lash in the gear adjusting mechanism. A method of testing was implemented which minimized the effects of lash in the pitch adjustment mechanism of the rotor. The test run would begin at the highest Mach number with the SR/FTR powered up from windmill to a maximum RPM and then the rig would be powered down in alternate RPM increments back to windmill. This proce- dure would then be repeated for the next lower Mach number and so on until the run was com- plete. With few exceptions this procedure was followed for the entire experiment.

Pressure Instrumention

To determine the net force generated by the propeller blades and the swirl recovery vanes both surface and intercavity pressures on the rig were recorded. A total of 40 nacelle pressures were recorded along with 20 body pressures.

Determination of Net Forces

The measurements of the propeller and vane net force must account for forces generated by internal pressures acting upon the rotor and vane balances in addition to forces generated by inter- actions with the nacelle, propeller spinner, and the vane hub. To determine drag corrections of the spinnerhub, nacelle, and vane hub, refer- ence drag runs were made with the propeller blades and swirl recovery vanes removed. These tests allow the measurement of a nacelle pressure drag tare as well as rotor and vane hub aerodynamic drag tares. During these tests the rotor was replaced with a dummy hub which had no holes for the propeller blades. The vane hub had the holes for the swirl vanes plugged up and taped over. Data was taken for Mach numbers ranging from 0.45 to 0.85. Forces that are measured or calculated are illustrated in Figure 5(a). The forces obtained for the tare runs for the spinnerhub, nacelle, and vane hub are re- spectively:

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W -D,,=RB, -CpA,,

where:pA=(p-p,)A

For the SWPTR with the propeller blades and swirl recovery vanes installed and thrusting the forces that are acting upon the model are illus- trated in Figure 5(b). The uncorrected thrust of the propeller, T,, , is defined as:

T ~ ~ = R B - C ~ A ~ + D, (2)

The propeller apparent thrust is obtained by subtracting the spinner drag increment that is the difference of the spinner drag with propeller blades installed and thrusting and spinner drag tare:

(3) - Tamp - T,P - AD*

V with: AD, =D, -D,, (4)

By substituting equations (2) and (4) into equa- tion (3) you have:

T,,,, =RB -CPA, + D,,l (5)

D.=J(P. -pa) (6)

By subtracting the nacelle drag tare from the "powered" nacelle pressure drag the nacelle drag increment is obtained:

The nacelle drag under powered conditions is:

AD, = D. - (7)

The net thrust of the propeller is obtained by subtracting the nacelle drag tare from the propel- ler apparent thrust:

TW.P = T 4R -AD**O, (8)

where o, is a weighting factor that accounts for interaction effects between the propeller, nacelle, and the swirl recovery vanes.

ne swirl recovery vanes are treated similarly with the uncorrected vane thrust defined as:

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T, = VB XpA,, - r p A u Db (9)

To determine the vane apparent thrust the vane hub drag increment is subtracted from the vane thrust: c

T,.y = T, - ADh (10)

The vane hub drag increment being: ADk =D, -Dh (1 1)

Substituting equations (9) and (1 1) into equation (10) gives:

TW," = VB + CpA,, - XpA, + Dkt (12)

The net vane thrust is the apparent vane thrust with the nacelle pressure drag increments sub- tracted from it:

T->"=Tapp,y-AD". 0" (13)

where: 0, = 1 - 0,

with oy representing the vane's interaction with the nacelle pressure drag.

By analyzing the nacelle drag coefficients under powered conditions for the forward, aft, and no vane configurations, the following values were obtained for the weighting values:

0, =0.9, o, =0.1 Vanes in forward position 0, = 1.0, a, = 0.0 Vanes in aft position op=l.O, o,=O.O No vanes installed

Total values of thrust are obtained by algebraic summation of the individual propeller and vane thrusts:

Tnet.ww=Tnrtp-Tl," (14)

To calculate a vane thrust coefficient the propel- ler operating conditions are referenced:

where n is the angular speed of the propeller.

The vane efficiency is calculated similarly:

with the power coefficient, C,, and the advance ratio, J , obtained from the propeller. These

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parameters are also used for the calculation of the total efficiency:

Results and Discussion

Design Vane Angle

Testing of the swirl recovery vanes centered primarily around the design operating condition of Mach = 0.80 with a design operating point of C, = 2.19 at J = 3.26. This power was achieved with a rotor blade angle measured at a .75 blade radius setting of = 63.3". The swirl recovery vanes were designed for optimum performance at a vane angle setting of 86. I". All testing took place at zero angle-of-attack for the SR/F'TR at Mach numbers ranging from M = 0.80 to M = 0.45. The test matrix of Mach numbers, blade angles, vane angles, and vane positions are displayed in Table VII. The maxi- mum test speed was 9000 RPM unless limited by blade or vane stress, high SRlPTR vibrations, high vane balance vibrations, or reaching the torque limitation on the rotor balance.

In Figure 6(a) the efficiency of the SR-7A rotor for the design blade angle, vane angle, and Mach number is shown, with the peak efficiency of 78.1 percent occurring at an advance ratio of 3.71. At the design advance ratio of J = 3.26 the efficiency of the rotor alone has dropped to 75.5 percent. In contrast, the vane efficiency in Figure 6@), exhibits no peak as the maximum RF'M is approached. The slope in the vane efficiency curve does, however, appear to be decreasing for the higher power conditions with an efficiency of 1.7 percent at J = 3.26 ob- tained. The total SRV efficiency which is, in essence, the summation of the rotor and vane efficiencies exhibits a peak which is moved to a higher operating speed at an advance ratio of approximately J = 3.40 (Fig. 6(c)). At the design advance ratio the SRV efficiency is now 77.2 percent with the efficiency curve somewhat flattened out. The change in efficiency due to the addition of the vane thrust is exhibited in Figure 6(d).

Thrust coefficients illustrating rotor, vane, L' and total SRV thrust as a function of advance ratio are shown in Figures 7(a)-7(c). The vane thrust behaves similarly to the rotor thrust as RF'M is increased although the magnitude of the vane thrust is much less than the rotor thrust. The rotor power absorbtion behaves much the same as in previous SR-7A rotor alone tests' (Fig. 8). With the power coefficient reaching a value of 2.24 for the design advance ratio of 3.26. For the operating range of the SRV at design conditions the ratio of the vane torque to the rotor torque is fairly constant with the vane torque at a value of roughly half the value of the front rotor (Fig. 9).

Vane Angle Study

To determine if the swirl recovery vanes were operating at their optimum vane angle an investigation was carried out at SRV design operating conditions with the vane angle varied through a range of 5.6". In Figure lO(a), for the swirl recovery vanes in the forward position, a distinct trend of rotor efficiency with respect to varying vane angle is not clear. In Figure lo@) the the effect of changing vane angle is more apparent. At the design advance ratio, J = 3.26, the 87.5" vane angle has a slightly higher vane efficiency at 1.9 percent than the 86.1" vane angle with 1.7 percent. As before, a peak in the vane efficiency does not occur within this operating range although it still appears that the slope of the vane efficiency curve is decreasing as the maximum RPM is approached. For the total efficiency illustrated in Figure lO(c), the maximum efficiency at the design advance ratio of 3.26 is 77.22 percent for a vane angle of 86.1" followed closely by the 87.5" vane angle with an efficiency of 77.15 percent.

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Figures 1 l(a)-ll(c) illustrate the behavior of thrust versus advance ratio for varying vane angles. As for the rotor efficiencies there ap- pears to be no distinct trends in terms of the rotor thrust. The highest vane angle tested, 88.9. shows the highest rotor thrust. The rotor efficiency (Fig. IWa)), however, shows no particular advantage to this vane angle. 'This pain's to the rotor hlddr angle k i n g slightly

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L greater for the 88.9" configuration, possibly due to the aforementioned lash in the blade angle setting gear. In Figure 1 I@) the vane thrust trends mirror the vane efficiency (Fig. lo@)) with the 57.5" vaae angle having a s!ightly high- er vane thrust coefficient than the 86.1" vane angle at the design advance ratio.

In Figure 12 the power coefficient for the front rotor as for the rotor efficiency and rotor thrust shows no clear indication of vane angle affecting rotor power. In contrast, the plot of vane torque divided by rotor torque versus ad- vance ratio in Figure 13 shows a dramatic differ- ence due to vane angle. At the design vane angle of 86.1" the torque ratio is the most con- stant for the operating range considered. For vane angles less than the design vane angle the torque ratio increases for increasing rotor power with an asymtotically approached torque ratio occurring at a value less than the design vane angle torque ratio. For vane angles greater than the design vane angle the opposite behavior is observed. .il Blade Annle Study

Figures 14-18 illustrate the rotor, vane, and total efficiency in addition the rotor power coef- ficient versus advance ratio for varying blade angles for Mach numbers of 0.80, 0.75, 0.70, 0.60, 0.45 respectively. The trends in efficiency qualitatively resemble the data presented for the design blade and vane angle at the design operat- ing condition. Of particular interest is that over a wide range of rotor powers and Mach numbers the vane efficiency does not peak but appears to level off as the maximum RPM is approached. The maximum vane efficiency achieved is 4.4 percent for the 63.3" rotor blade angle at M = 0.60 at a power coefficient of 2.82 and an ad- vance ratio of 2.69. In addition, for the wide range of Mach numbers and rotor powers tested the torque ratio of the vane torque divided by the rotor torque is almost constant with the vane torque approximately half of the rotor torque as illustrated in Figure 19.

Vane Position Study

In Figures 20-31, power coefficient, thrust coefficient, and vane to rotor torque ratio are plotted versus advance ratio for the five Mach numbers tested in the forward vane, aft vane, and rotor alone configuration. In varying vane position, small differences in thrust and power led to small and sometimes ambigous differences in efficiency. For this reason only the power and thrust coefficients in addition to the vane to rotor torque ratio are shown.

In figures of power coefficient versus ad- vance ratio (Figs. 20 and 21) there appears to be a general trend of slightly lower rotor loading for the forward vane position. The indications of this trend are strengthened when the rotor alone results are included in the observation of the data. The rotor, vane, and total thrust coef- ficients tend to indicate the same trend of a lower thrust coefficient for a more forward vane position. This slight effect of rotor loading varying with vane positions is echoed by acous- tic results?

While power coefficients for the rotor and thrust coefficients for the SRV configuration show small differences, the vane to rotor torque ratio can possibly indicate greater differences due to vane position. This is due to the fact that the values of vane torque, as opposed to the vane thrust, are of the same order of magnitude as the rotor torque. In addition, any coupling effects between the rotor and the swirl vanes are likely to become immediately apparent. Still, the scale for vane to rotor torque ratio was enlarged to allow differences of one percent or more to be easily observed.

In the display of the torque ratio data as a function of vane position, only data taken at maximum RPM decreasing to windmill are plot- ted. This is due to a slight hysterises in the torque ratio that would make plotting the entire set of data for vane position cluttered. In plot- ting only the decreasing power vane to rotor torque ratio eTQ), the general trends are still indicated with the aft vane position data closely following the forward vane position with a slcrr-

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er indication of the differences in magnitude in RTQ due to vane position.

In Figure 27 the effect of power on the shape of the torque ratio curves is evident with the lower power absorbtion blade angle (57.33 showing an increase in the torque ratio with RF'M. At the higher power blade angle settings of 60.2" and 63.3" a peak appears in the torque ratio curve. This effect persists for the lower Mach numbers (Figs. 28-31) with a power coef- ficient of approximately 1.5 appearing to be the point at where the torque ratio curve begins to P d .

By moving the swirl recovery vanes from the aft to the forward position, the vane to rotor ratio, almost without exception, increases. The increase is generally on the order of 4 to 5 per- cent. Similar behavior has been seen in counter- rotating propeller ~ys tems.~ This would seem to indicate that the loading in the vanes is higher for the more forward position. The vane thrust coefficient, however, tends to decrease slightly for the more forward position, as mentioned earlier (Figs. 22-26). One possible explanation for this is that if the drag on the swirl recovery vanes increase then the vane thrust will decrease while the lift and drag vectors of the vane are additive in the direction normal to the rotational axis with a resultant increase in vane torque. Thus the apparent increase in vane loading mea- sured in vane torque corresponding to a slight unloading of the rotor is in most cases not re- flected in a general increase in vane thrust for the more forward vane position.

Summarv of Result$

An experiment was conducted in the NASA Lewis 2.44 x 1.83 m (8 x 6 ft) Supersonic Wind Tunnel to determine the increase of efficiency obtained by swirl recovery vanes that were de- signed to operate within the wake of an ad- vanced high speed propeller. Due to difficulties encountered in operating the swirl recovery vanes with the original SR-3 high speed propel- ler a SR-7A high speed propeller was suhstitut- ed.

At the design Mach number of 0.80 with the v SR-7A propeller operating at an advance ratio of J = 3.26 with C, = 2.24 the swirl recovery vanes provided an increase of 1.7 percent over the SR-7A's efficiency for a total efficiency of 77.2 percent at the design vane angle of 86.1".

In varying the vane angle a slightly higher vane efficiency was obtained with the 87.5" vane angle for the forward vane position. The design vane angle, however, still exhibited the highest total efficiency. One indicator that the design vane angle of 86.1" is the optimum vane angle is that the vane to rotor torque ratio is nearly con- stant at approximately at a value of 0.5 over the operating range tested. The other vane angles exhibited different torque ratio behavior with rotor power dependent on their being at higher or lower angles than the design vane angle.

With different SR-7A blade angles the effect of different swirl inputs to the swirl recovery vanes was investigated. The vane efficiency, appearing to level off, did not peak even with the higher rotor powers. The maximum vane efficiency of 4.4 percent was also the maximum rotor power achieved during the test with C, = 2.82 at an advance ratio J = 2.69 for the 63.3" blade angle at a Mach number of 0.60.

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The effect of moving the swirl recovery vanes from their nominal position to a point 16.38 cm (6.45 in) further aft was also investi- gated. No clear effect on vane efficiency was seen as a result of moving the vanes rearward. Small differences in rotor power coefficients suggest a slight unloading of the SR-7A propel- ler as the vanes are moved closer to the propel- ler. A consistent effect of an increasing vane to rotor torque ratio for the more forward vane position was noted regardless of the direction of small differences in the vane thrust. This is possibly due to the vane orientation being such that the lift and drag vectors act to make to vane torque increase regardless of increasing or de- creasing vane thrust.

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Figure 1. - Photograph of the swirl recovery vanes in the forward position in conjunction with SR-7A high speed propellers as installed in the NASA Lewis 2.44 x 1.83 rn (8 x 6 f t ) Supersonic Wind Tunnel.

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References

1. Foss, R.L., and Hopkins, J.A., “Fuel Con- servation Potential for the Use of Turboprop Powerplants,” SAE Paper 76-0537, May 1976.

2. Whitlow, J.B. Jr., and Sievers, G.K., “Fuel Savings Potential of the NASA Advanced Turboprop Program,” NASA TM-83736, 1984.

3. Biermann, D., and Hartman, E.P., “Wind- Tunnel Tests of Four- and Six-Blade Single- and Dual-Rotating Tractor Propellers,” NACA Report 747, 1942.

4. Rohrbach, C., Metzger, F.B., Black, D.M., and Ladden, R.M., “Evaluation of Wind Tunnel Performance Testings of an Ad- vanced 45” Swept Eight-Bladed Propeller at Mach Numbers from 0.45 to 0.85,” (NASA Contract NAS3-20769) NASA CR-3505, 1982.

5. Goldstein, S., “On the Vortex Theory of Screw Propellers, Proceedings of the Roval Aeronautical Society,” Series A, Vol. 123, 1929, pp. 440465.

6 . Swallow, R.J., and Aiello, R.A., “NASA Lewis 8- by 6-Foot Supersonic Wind Tun- nel,“ NASA TM X-71542, 1974.

7. Stefko, G.L., Rose, G.E., and Podboy, G.G., “Wind Tunnel Performance Results of an Aeroelastically Scaled 2/9 Model of the FTA Flight Test Prop-Fan,” AIAA Paper 87-1893, June 1987.

8. Dittmar, J.H., and Hall, D.G., ‘The Effect of Swirl Recovery Vanes on the Cruise Noise of an Advanced Propeller,” AIAA Paper 90-3932, Oct. 1990.

9. Jeracki, R.J., National Aeronautics and Space Administration: Lewis Research Center, Private Communications, 1992.

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(a) Swirl recovery vanes as installed in the forward vane position.

(b) Swirl recovery vanes as installed in the aft vane position.

W Figure 2. - Schematic of swirl recovery vanes as installed on the propeller

test rig illustrating both the fore and aft vane positions.

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Table 1. - Design Characteristics of the Swirl Recovery Vane

Sweep angle

I Number of vanes I 8 I 40"

Integrated design lift coefficient, C,

I Vane model diameter I 62.23 cm (24.5 in) I

0.344

I Activitv factor. AF I 174 I

Airfoils NACA-16

Ratio of nacelle maximum diameter to vane diameter

Cruise design Mach number

Cruise design advance ratio (referenced to propeller)

Cruise design power coefficient (referenced to propeller)

(at 10,OOO m 135,000 ftl

Power loading at design power coefficient I.S.A. altitude)

2.19

228.6 mlsec (750 Wsec) Tip speed at design power coefficient (referenced to propeller)

321.1 h / m 2 (40 shplft+)

0.35

0.80

3.26

0.08

0.07

0.06

0.05

0.04

0.03

0.02

0.50 o'60 i - -

- -

- - - - - -

- - -

- - -

- L -1 ' " ' l ' ' . l " ' l ' ' ~ . ~ ~ ~ , ~ ~ ~ ' ~ , ~ ~ ' , ~ , L

0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Vane radiusfip radius. r/R

Figure 3. - Variation of vane design parameters with vane radius for the swirl recovery vane.

Table 11. - Design Characteristics of the S R J A Propeller Blade

Number of blades

Tip sweep angle (geometric planform measurement)

Nominal uroDeller model diameter W

8

41"

62.23 cm (24.5 in)

v

Integrated design l i f t coefficient, C,

Airfoils

0.202

NACA-65ICA and NACA-16

Ratio of nacelle maximum diameter to propeller diameter

0.20 0'24 i

0.35

0.00 0.04 1

20

1 6 w W u

s 12 W m C 0

-

w 8 c 0 0

$ 4

W m -

6 0 c v)

3 t-

._ -4

-a 0 3

Figure 4. - Variation of propeller design parameters with blade radius for the SR-7A high speed propeller. Blade characteristics are shown for the deflected blade position at the original cruise design condition of C. = 1.45, J = 3.06, at Mach = 0.80.

W

13

- I -

1 0.056 I 0.899 I

Model Station X&

I 0.298 I 0.954 I

Radius 8 r/R.

1 0.388 I 0.968 1 0.512 0.981

Table IV. - Body Static Pressure Tap Location (RN = 11.036 cm [4.345 inJ)

0.730

v

0.995

14

v

Model Station (Fwd.) X R 4

0.926

0.926

Model station=O.O

Model Station (Aft) Radius 0 X& 1 4 4

2.411 0.961 45', 135", 225', 315'

2.411 0.906

Table V. - Rotor Cavity Static Pressure Tap Location IR. = 11.036 cm [4.345 in])

0.926

2.577

Model Station

-0.057

2.411 0.850

4.063 0.978 112.5". 1573 , 202.5". 247.5'

3.156 4.641 0.978 2 2 3 , 67.5", 2 9 2 3 , 337.5"

B, .rice face static pressures '-'?looking downstream)

Radius I 0 i

i 0.848 1 'P. 4 7 W, 135" 180".

225", 27@, 315*

0.769 45". 135". 225". 315'

180". 270" 0.751

0.722 45'. 135'. 225". 3 15'

45". l35', 225'. 315'

Balance station 1

I Balance station 2 157.5" I 202.5"

LBalance cutout

Vane balance

22.5" ' 337.5"

Balance cutout static pressures (looking upstream)

15

-Dw . \

'Rotor Balance, R B t d

(a) Forces acting on the balances during tare runs.

'Rotor Balance, RB-t

(b) Forces acting on the balances during test runs.

V

u Figure 5. - Buoyancy force diagram of the propeller test rig configured

for the swirl recovery vanes for tare and test runs.

16

v

Table VU. - Swirl Recovery Vane Test Matrix (For vane angle, 0, = 86.13

F = Forward Vane Position

A = Aft Vane Position

N = No Vanes InstaIled

I I I I I

'Also tested with vane angles 0, = 83.3", 84.7", 87.5", 88.9" (Forward vane position) 0, = 84.7", 87.5", 88.9" (Aft vane position)

W

17

0.80

0.75

h 0.70 5 c al - 2 0.65 c= e k .u

$ 0.60

0.55

0.50 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6

Advance ratio. J

0.60

0.55

0.50

0.80

0.75

a 5 6 0.70

c al ._ .i! 0.65 L L 0

0 - .u

2 0.60

0.55

0.50 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6

Advance ratio. J

0 0

-

- -

I 1 1 1 1 1 l I l I I S

0.06

0.02

-0.02

z & -0.06

c -0.10 at

D -0.14

5 .- 0 .- L c

0 C 22 -0.18

-0.22

-0.26

-0.30 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6

Advance ratio. J 0

0.80 , Rotor efficiency

0 0.75 a

0.70 c

U

0 Total efficiency 0

Id)

Figure 6. - Rotor (a), vane (b), and total (c), efficiencies in addition to efficiency increment (d) versus advance ratio for a vanes forward configuration with /3, = 63.3", p2 = 86.1" at Mach = 0.80.

W

18

0.70

6 0.60 0.50

0.40

(a) v 0.30

v, 0.20 2

W

- 4

.- V

a 0

.-

+

5 0.10 L 0 0 E 4-d 0.00

-0.1 0

v

0.06 ' 0.04 4-d-

0 0.02

0 0.00

c P) .- .- 'c 'c P)

(b) u

2 -0.02 5

2-

.P v)

9) -0.04 C

-0.06

0.70

&* 0.60 .I-- c 0.50 0) 0 .- 0.40 9)

(C) V 0.30

v) 0.20 2 5 0.10

2 0.00

-0.10

.- L

c

- 0 I-

3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 Advance ratio. J

Figure 7. - Rotor (a). vane (b), and total (c) thrust coefficients versus advance ratio for a vanes forward configuration with /3, = 63.3", { j2 = 86.1" at Mach = 0.80.

19

2.4 2.2 2.0 +-

C w 1.8 0

Le 1.6 W 0 1.4 u I 1.2

1.0 a 0.8 o 0.6

w 0.4 0.2 0.0

0" .- .- \i-

0

I

.+ 0

3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 Advance rotio, J

Figure 8. - Power coefficient versus advance ratio for a vanes forward configuration with p, = 63.3", p2 = 86.1" at Mach = 0.80.

2.0

0 1.7

1.4 t- w 0 .-

-w I rJ 1.1

Y- 0.5

a, 0.8 3

0 -w

0.2 0 0 -0.1 E 2 -0.4

-+

K

-0.7

-1 .o 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6

Advance ratio, J

Figure 9. - Vane to rotor torque ratio versus advance ratio for a vanes forward configuration with p, = 63.9 , pz = 86.1"at Mach = 0.80.

v

W

W

20

0.80

c b 0.75

>; 0.70

0 0.65

s V C a, .- .- c c a,

0 L 0.60 c

0.55

0.50

0.06

0.02 0 e -0.02

5 -0.10

-0.18

6 -0.22

c 5 -0.06 .- V

(u

a,

E -0.14

> -0.26

-0.30

0.80

0.75

0.70

0.65

- 0.60

2 0.55

0.50 3

F >; V c a, V

a,

0

.- .- -4- -4-

c

0 A

.O 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 Advance ratio, J

Vane angle

0 p2=83.3" 0 p2=84.7" 0 p2=86.10 A p2=a7.5"

p2=88.9"

Figure 10. - Rotor (a), vane (b), and total (c) efficiencies versus advance ratio for a vanes forward configuration with p, = 63.3" a t Mach = 0.80 with varying vane angle (p2) .

^.

0.70

cf 0.60

a, 0.50

E 0.40

(a) o 0.30

ln 0.20 2

- c

.- 0

a 0

.-

u

5 0.10 I 0 + 0.00 0 K

-0.10

0.02

u- C W .- " -0.02

-0.04

.- c c W

u 67 2 -0.06 5 W -0.08

-0.10

c 5

0.70

d* 0.60 u- c 0.50

.- 0.40

0 0.30 (C) 0

ln 0.20 2 5 0.10

2 0.00 P

W 0

0)

.- c

u

-

-0.10 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6

Advance ratio, J

Figure 11. - Rotor (a), vane (b), and total (c) thrust coefficients versus advance ratio for a vanes forward configuration with p, = 63.3" a t Mach = 0.80 with varying vane angle

22

... ...

W 2.4

2.2 - 2.0

a, 1.8

0" 4.d c 0 .-

Vane angle .- LC 1.6 a, 0 1.4 p2=83.3" 0 0 82=84.7" I 1.2

\c

0 p2=86.l0 1.0 A 82=87.5:

v 82~88.9 0 a 0.8

o 0.6

0.4 0.2 0.0

I

c 0

3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 Advance ratio, J

Figure 12. - Power coefficient versus advance ratio for a vanes forward configuration with p1 = 63.3" at Mach = 0.80 with varying vane angle (&).

v 2.0

I- 0 1.7

- 1.4

1.1 F Vane angle

0 &=83.3" (u 0.8

0- 0.5 0 82=84.7" c 0 0 B2=86.l0 L 0.2 A /?2=87.5: c 0 v 82=88.9 0 -0.1

> -0.4

IY

0 .- c

3

IY

K

3 -0.7

-1 .o 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6

Advance ratio, J

Figure 13. - Vane to rotor torque ratio versus advance ratio for a vanes W forward configuration with p1 = 63.3" at Mach = 0.80 with varying vane angle (&I.

23

0.82 e F 8 0.72 o 0.62

L. 0.52

0.42

c m .- .- *- c m

0 .e

m c P t 2

>; 0 K a, u w a,

.- L

a, K

3

0.05

-0.05

-0.15

-0.25

-0.35

5 K a, u

a,

.- .- c *-

- 0 0 + c

0.82

0.72

0.62

0.52

0.42

Blade angle 0 /9,=57.3O

/31=60.1° 0 /31=63.3O

v

3.0

2.5 0"

.- u 2.0

0 1.5

.e- K a, .- c 'c 0 0

L a, g 1.0 a

b 0.5 0 oc

0.0

c

2.0 2.5 3.0 3.5 4.0 4.5 5.0 Advance ratio, J

Figure 14. - Swirl recovery vane performance for a vanes forward con- figuration with p2 = 86.1" at Mach = 0.80 with varying blade angle (@,).

24

L - e c >; 0 c al 0

Q)

._

._ c c I

c 0 0 oc 0 c P c 5 C al 0

al

.- .- c c

0.82

0.72

0.62

0.52

0.42

c

0.05

-0.05

-0.15

-0.25

-0.35

5 c al u

al

1- .- c c - 0 0 c c

0.82

0.72

0.62

0.52

0.42

Blade angle '

0 /?,=57.3O 81=60.1°

0 /?1=63.3'.

3.0

2.5

.- 0 2.0 ?=

0 1.5

u" +- C al

1-

al 0

L al g 1.0 a

& 0.5 0 rx

0.0

4d

2.0 2.5 3.0 3.5 4.0 4.5 5.0 Advance ratio, J

w

Figure 15. - Swirl recovery vane performance for a vanes forward con- figuration with p2 = 86.1" at Mach = 0.75 with varying blade angle (p,).

25

L c e F 2; 0 C aJ 0

0

._

.- c c I

Y 0 0 cc

0.02

0.72

0.62

0.52

0.42

0 c z t=

al c 5

0.05

-0.05

-0.15

-0.25

-0.35

- 0 0 I-

Y

0.82

0;72

0.62

0.52

0.42

Blade angle

0 B,=57.3" A /31=54.1"

0

0 &=SO.l "

63.3"

W

3.0

2.5

.- 0 2.0

1.5

0" c- c al .- 1c c al

I 0)

Q g 1.0

6 0.5

0.0

4.d

0 [y:

2.0 2.5 3.0 3.5 4.0 4.5 5.0 Advance ratio, J

Figure 16. - Swirl recovery vane performance for a vanes forward con- figuration with p2 = 86.1" at Mach = 0.70 with varying blade angle (p,).

26

U

w

0.82

0.72

0.62

0.52

0.42

0.05

-0.05

-0.15

-0.25

-0.35

0.82

0.72

0.62

0.52

0.42

.t- c e, 0

W 0 V

.- .- z I al 2 a I

c 0 0 rY

3.0

2.5

2.0

1.5

1 .o

0.5

0.0 2.0 2.5 3.0 3.5 4.0 4.5 5.0

Advance ratio, J

Blade angle A 8,=54.1" 0 0 0

, I

p1=57.30 PI =60.1 /3,=63.3"

Figure 17. - Swirl recovery vane performance for a vanes forward con- figuration with & = 86.1" at Mach = 0.60 with varying blade angle (PI).

21

L

3 e F

I

+ 0 0 rx

0.82

0.72

0.62

0;52

0.42

0.05 B r 5 -0.05 c a, 'G -0.15

-0.25

.- L L a,

a, c 0 > -0.35

0.82 &2

5 . 0.72

2 0.62

c a, .- L L a, - 0.52

0.42

+ 0 t-

e- c a, 0

a, 0 0

.- 1-

L L

I a,

a I

e 0 0 E

3.0

2:5

2.0

1.5

1 .o

0.5

0.0 1 .o 1.5 2.0 2.5 3.0 3.5 4.0

Advance ratio. J

Blade angle A pj=54.lo 0 p,=57.3O

Figure 18. - Swirl recovery vane performance for a vanes forward con- figuration with Pz = 86.1" at Mach = 0.45 with varying blade angle (p , ) .

28

1 .o 0.8

0.6

0.4

0.2

0.0

v

(a)

1 .o 0.8

0.6

0.4

0.2

0.0

v

0- 1.0

e 0.8

? 0.6

o 0.4

.- 4d

(c) p 44

5 0.2 u 0

\ K 0.0

Blade angle

A pl=54 . lo

p1=60.10 /3,=63.3O

0 /3,=57.3"

W- C

3 1 .o 0.8

0.6

0.4

0.2

0.0 i 1.0 2.5 3.0 3.5 4.0 4.5 5.0

1 .o 0.8

0.6

0.4

0.2

0.0

(e)

1 .0 1.5 2.0 2.5 3.0 3.5 4.0 Advance ratio, J

Figure 19. - Vane to rotor torque ratio versus advance ratio for a vanes W

forward configuration with p2 = 86.1" and varying blade angle ([{,I for Mach = 0.80 (a), Mach = 0.75 (b), Mach = 0.70 (c), Mach = 0.60 (d), and Mach = 0.45 (e).

29

3.0

0" j 2.5

.s 2.0 t

0 1.5

C 9) .-

a, 0

L al

$ 1.0 a L

-+ 0 0.5 0

LT 0.0

3.0

0" j 2.5

$

c al .- .o 2.0

0 1.5

L Lc

L al z 1.0 a

0.0

3.0 0" j 2.5

.I! 2.0

0 1.5

C a, .-

-4- Lc al 0

L al 2 1.0 a L

c 0 0.5

0.0 2

0 LT

Vane position o Vanes fwd.

Vanes af t 0 No v a n e v

:.0 2.5 3.0 3.5 4.0 4.5 5.0 Advance ratio, J

\

Figure 20. - Power coefficient versus advance ratio, varying vane position with l j , = 86.1" and varying blade angle (p,) for Mach = 0.80 (a), Mach = 0.75 (b), and Mach = 0.70 (c).

30

W

v

3.0

2.5

2.0

1.5

1 .o

+- c 0.5

0.0 e, 2

0" a, 0 .- ._ 0 0 .I

.o 2.5 3.0 3.5 4.0 4.5

~ s 0 a L

.+., 0 0 CY

3.0

2.5

2.0

1.5

1 .o

0.5

0.0 1 .o 1.5 2.0 2.5 3.0 3.5

Advance ratio, J

5.0 c Vane position o Vanes fwd

Vanes a f t 0 No vanes

I

4.0

-Figure 21. - Power coefficient versus advance ratio, varying vane position with Mach = 0.45 (b).

= 86.1" and varying blade angle (p , ) for Mach = 0.60 (a), and

31

0.70

cf 0.60

0.50

c - 0.40

v 0.30

v, 0.20 2

+-

.- V

al 0

.-

4

5 0.10 I 0 0 E + 0.00

-0.10

0.06

0.04

0 0.02 .- L c Vane position 0 0.00 o Vanes fwd. c 0 Vanes aft VI 0 No vanedv' 2 -0.02 5

3

tz

.+ S al .- al V

-0.04 C

-0.06

0.70

& 0.60 c 0.50

.- 0.40

0 0.30

- Y

al U

a U

.- c

% 0.20 2 5 0.10

2 0.00 - 0

I-

2.0 2.5 3.0 3.5 4.0 4.5 5.0 Advance ratio, J

L, Figure 22. - Rotor, vane, and total thrust coefficients versus advance ratio,

varying vane position with p2 = 86.1" and varying blade angle (PI) for Mach = 0.80.

32

0.70

6 0.60

$ 0.50

2 0.40

o 0.30

0.20

W

i

.- 0

W 0

.-

-c(

2 5 0.10 L 0

.+- 0.00 0 Ilf

-0.1 0

0.06

z 0.04

" 0.02

c t W .- .- 1c Lc a 8 0.00 .+. Lo 2 -0.02 5

>" -0.04 c

-0.06

Vane position o Vanes fwd.

Vanes a f t 0 No vanes

0.70

8 0.60 +- c 0.50

1c 0.40

0 0.30

Lo 0.20 2 5 0.10

3 0.00 P

W 0

9)

0

.- .- 1c

-+

-

-0.10 2.0 2.5 3.0 3.5 4.0 4.5 5.0

Advance ratio, J

W Figure 23. - Rotor, vane, and total thrust coefficients versus advance ratio,

varying vane position with p2 = 86.1" and varying blade angle (if,) for Mach = 0.75.

33

0.70

cf 0.60 +- $ 0.50

0.40

u 0.30

0.20

0.10

.w 0.00

-0.10

.- 0

m 0

.-

c

2 r L 0 0 IY

0.06 ' 0.04 e-

0.02 S al .-

Vane position .- L L m 0 u 0.00 o Vanes fwd. c o Vanes 2 -0.02 0 No vanes

3

"v .c c g -0.04

1 1 1 1 1 1 1 1 1 1 1 1 1 1 ~ 1 1 1 1 1 l ~ l l l l l l ' ' I " " " I " ' I ' ' @ I ' I I -0.06 I I " " ' 0.70

0' 0.60 c- K 0.50 m .- .- 2 0.40 L m V 0 0.30

vf 0.20 2 5 0.10

.Id

- 3 0.00

-0.1 o 2

0 I-

.o 2.5 3.0 3.5 4.0 4.5 5.0 Advance ratio, J

u Figure 24. - Rotor, vane, and total thrust coefficients versus advance ratio,

varying vane position with p2 = 86.1" and varying blade angle (p , ) for Mach = 0.70.

34

-.

0.75

cf 0.65 *- 5 0.55 0

0.45 al 0 u 0.35

v, 0.25

5 0.15

c 0.05

u

.- .-

c

2

L 0 0 rY

-0.05

v

0.06

0.04 c- K W .- 0 0.02 .- Y- c Vane position

o Vanes fwd. 0 0.00 Vanes a f t

v) 0 No vanes 2 -0.02 5

2

W

V

c

0 -0.04 c

-0.06

0.75

6 0.65 c 0.55 c- B1=5 al .- .- 2 0.45 c al $ 0.35

v) 0.25 2 5 0.15

3 0.05

c

- 0 I-

-0.05 2.0 2.5 3.0 3.5 4.0 4.5 5.0

Advance ratio, J

'W Figure 25. - Rotor, vane, and total thrust coefficients versus advance ratio,

varying vane position with p2 = 86.1" and varying blade angle (p , ) for Mach = 0.60.

35

Vane position o Vanes fwd.

Vanes aft 0 No v a n e W

c' 0

+ v1

2 5 - 0 c 0 I-

0.75

0.65

0.55

0.45

0.35

0.25

0.15

0.05

-0.05 1

~

I I I I I I I T I I I i r r r i i m I 1 I I W I I I

.o 1.5 2.0 2.5 3.0 3.5 4.0 Advance ratio. J

v Figure 26. - Rotor, vane, and total thrust coefficients versus advance ratio,

varying vane position with j3, = 86.1" and varying blade angle (p , ) for Mach = 0.45.

36

0.55 0

0- 0.53 k v

.- + L 0

a, 0.51 3 U p 1=57.3" $

0.49 Y

L

.+4 0 0 lY 0.47

' 0.45

-2 c

0.55 E lY 6 0.53 .- +J P a, 0.51 3

p1=63.3" F o 0.49 Y

L

Y 0 0 5 0.47

' 0.45

c 0

5.0 2.0 2.5 3.0 3.5 4.0 4.5 Advance ratio, J

W

Figure 27. - Vane to rotor torque ratio versus advance ratio, varying vane position with p2 = 86.1" and varying blade angle ( f f , ) for Mach = 0.80.

37

81 =57.3"

0.52 P CY

9) 0.48 3 0- L 0 c L

.y

0.46 0 0

% 0.44 c 0

0.42

6 0.50 .- Y 0 L

Q) 0.48 3

81=60.1° 5 0.46 +

L

.I-. 0 0 s 0.44 c 0 > 0.42

0.52 0

6 0.50 k .- I

?

,!?,=63.3' Q) 0.48 3

0 E?-

0.46 * L

cr 0 0

0.44 Q) c 0 > 0.42

2

Vane position o Vanes fwd. C] Vanes a f t

W'

I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I I I I I I I .o 2.5 3.0 3.5 4.0 4.5 5.0

Advance ratio, J

ii Figure 28. - Vane to rotor torque ratio versus advance ratio, varying vane

position with p2 = 86.1" and varying blade angle (p,) for Mach = 0.75.

38

TI I I

0.49

0.47

0.45 p,=57.3O

.- ' 0.43 4

F p) 0.41 3 0- 0 L 0.51

0.49

0.47

2 0.45

0.43

0.41

-v v 2 4 0

o a p1=60.1 c

0.51

0.49

0.47

0.45

0.43

0.41

pl=63.3'

2.0 2.5 3.0 3.5 4.0 4.5 5.0 Advance ratio, J

Vane position ' o Vanes fwd.

Vanes a f t

Figure 29. - Vane to rotor torque ratio versus advance ratio, varying vane position with p2 = 86.1" and varying blade angle (PI) for Mach = 0.70.

39

pj=54.1 O

0.51

0.49

0.47

0.45

0.43

0.41

l l l l l l l l P I I I I I I I I I I I I I 1 I l l I l l

0.51

0.49

0.47

$ 0.45

0 .s 0.43

a, 0.41

p i = 5 7 . 3 ' ~

~

2 Vane position

0.51 Vanes af t o Vanes fwd.

v Y

0 Y

;j 0.49 4 0 $ 0.47

pl=60.1 2 0.45

0.43

0.41

0.51

0.49

0.47

0.45

0.43

0.41

p1=63.3'

2.0 2.5 3.0 3.5 4.0 4.5 5.0 Advance ratio, J

i/

Figure 30. - Vane to rotor torque ratio versus advance ratio, varying vane position with p2 = 86.1" and varying blade angle (p , ) for Mach = 0.60.

40

0.50

0.48

0.46 Pl=54.l0

u 0.44 z

a, U y 0.40 L

+ 0

0.50 L

.t- 0

W 0 0.48

' 0.46

e, C

8,=57.3O 0.44

0.42

0.40 1 .o 1.5

Vane position o Vanes fwd.

Vanes af t

2.0 2.5 3.0 3.5 4.0 Advance ratio, J

Figure 31. - Vane to rotor torque ratio versus advance ratio, varying vane position with p2 = 86.1" and varying blade angle (p , ) for Mach = 0.45.

41