PERFORMANCE ANALYSIS OF HOVERING UH-60A ROTOR BLADE

(1)

박 영 민,^*1 최 인 호,²장 병 희³

P ERFORMANCE A NALYSIS OF H OVERING UH-60A R OTOR B LADE Y.M. Park,

^*1

I.H. Choi

²

and B.H. Chang

³

The present paper describes the results of performance analysis for UH-60A rotor blade in hover. For the numerical simulations, commercial CFD software, FLUENT was used with Spalart-Allmaras turbulence model. The flow solver was based on node based scheme and second order spatial accuracy options was used for simulations.

For the enhancement of wake capturing capability, high resolution grid was used around tip vortex region. Granting that somewhat over-prediction of thrust was observed near blade tip region, performance was well correlated with experimental data within 3% accuracy in the operating region. Finally it was shown that the present flow solver can be used as a preliminary performance analysis tool for hovering helicopter rotor blades.

Key Words :

(CFD), (hovering), (performance), UH-60A(UH-60A), (rotor blade)

Corresponding author, E-mail: [email protected]

1. (CFD)

Caradonna and Tung [1] UH-60A [2]

. Caradonna and Tung

. UH-60A

[3-8]

.

tip vortex

free wake method, lifting line method, vortex embedding [4-6]

.

tip vortex modeling CFD

[7,8].

FLUENT

[9] Caradonna and Tung TRAM

.

FLUENT UH-60A

. collective pitch

(FM) .

FLUENT .

2.

2.1 FLUENT

3D, steady, implicit, Navier-Stokes, segregated type, node-

based . Spalart-Allmaras

turbulence intensity turbulence length scale

(2)

Fig. 1 Planform of UH-60A rotor blade

r/R

TwsitAngle

0.00 0.20 0.40 0.60 0.80 1.00

-4 -2 0 2 4 6 8 10 12 14

Fig. 2 Twist angle distribution of UH-60A rotor blade

Fig. 3 Surface mesh distributions of UH-60A blade

Fig. 4 Periodic boundary mesh and blade surface

0.1%, 0.01m .

2 upwind .

(periodic boundary)

pressure-inlet . FLUENT

pressure-inlet (total pressure)

. pressure-inlet

starting vortex circulation

.

2.2 UH-60A

UH-60A [10]

.

SC1095 SC1094R8 Fig. 1

. SC1094R8 SC1095 droop

1 .

SC1094R8 1 twist

.

Fig. 2 UH-60A twist

. Twist [10]

.

linear transition sweep

0.93R trailing edge leading edge 20

. chord

aerodynamic center . Fig. 3

200 . 25

.

Fig. 4 wake

. 5~6

(node) (cell)

4M 5.7M .

.

3. UH-60

3.1 Mach 0.65 4.3, 5.5, 7.3, 8.5, 9.1, 10.5, 11.0, 11.8

.

(3)

_{} _ _ 

Experiment[2]

- 0.0850 0.00690 0.73

Present ^

0.0848 0.00694 0.72 Table 1 Comparison of FM at

_

=0.085

Iteration CT/σ

0 4000 8000 12000 16000 20000 24000

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16

Collective Pitch =11deg

Collective Pitch =4.3 deg

Fig. 5 Convergence histories for high and low thrust condition

C ollective P itch CT/σ

4 5 6 7 8 9 10 11 12

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14

Experim ent

Experim ent with 1.2^oOffset Present

Fig. 6 Collective pitch and thrust coefficient for UH-60A rotor blade

C_T/σ

FigureofMerit

0.02 0.04 0.06 0.08 0.1 0.12 0.14

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Experiment Present

Fig. 8 Thrust and figure of merit for UH-60A rotor blade

C_T/σ CQ/σ(x10-3 )

0.020 0.04 0.06 0.08 0.1 0.12 0.14

2 4 6 8 10 12

Experiment Present

Working Range

Fig. 7 Thrust and power coefficient for UH-60A rotor blade

Fig. 5 4.3 11.0

. starting

vortex momentum

theory source sink

[8]. Starting vortex

.

Fig. 6 [2]

1.2 . 1

SC1094R8 twist

.

. Fig. 7

.

FLUENT [9]

.

Fig. 8 FM(Figure of Merit)

. ( : 0.006~0.01) 3%

FLUENT .

11.8 FM .

Table 1 ( 

_

 =0.085)

FM 0.01 .

1.5% (pitch

angle= 4.3 degree) FM 5% .

Fig. 9

.

[8] .

tip vortex

(4)

r/R ΔCT/Δr

0.0 0.2 0.4 0.6 0.8 1.0

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

Present(5.7M Cells) S traw n[8 ](1 0.6 M Cells) S traw n[8 ](6 4.0M Cells) Ex periment

Fig 9. Sectional thrust distributions of UH-60A rotor blade (

_

=0.085)

(a) rectangular tip (b) round tip

Fig. 10 Iso vorticity contour after 45 deg azimuth angle

Fig. 12 Iso-vorticity distributions of UH-60A rotor blade

r/R ΔCT/Δr

0.0 0.2 0.4 0.6 0.8 1.0

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

Present(Rectang ular Tip) Present(Ro und Tip) Ex periment

Fig. 11 Sectional thrust distributions of UH-60 rotor blade (

_

=0.085)

vortex . vortex

[8].

10.6M 64M

5.7M .

3.2 Tip

vortex

Fig. 10 round

.

tip vortex .

45 5% vortex

strength .

tip vortex .

Fig. 11

inboard tip vortex

. vortex core 0.95R

. .

3.3 Vortex Capturing

Fig. 12 iso-vorticity

vortex trajectory 360

. tip vortex

.

0.95R vortex core

. vortex core

[8]

.

[8] vortex core miss distance

0.2c miss

distance 0.21c .

0.4c vortex

(5)

C_T/σ

FigureofMerit

0 .0 2 0 .0 4 0 .0 6 0 .0 8 0 .1 0 .1 2 0 .1 4 0 .0

0 .1 0 .2 0 .3 0 .4 0 .5 0 .6 0 .7 0 .8 0 .9 1 .0

E xp erim en t

P resen t(w ith co rrectio n )

Fig 13. Thrust and figure of merit for UH-60 rotor blade (after power coefficient correction)

0.21c . Miss distance

,

.

3.4 Fig. 13

. V-22

[11]

. 7%

( 

_

 ) 0.00015 .

FM 1% .

(pitch angle=4.3degree)

1.5% .

4. FLUENT UH-60A

.

collective pitch 1.2

. FM

3%

. vortex

core

vortex

core .

FLUENT

.

[1] 1981, Caradonna, F.X. and Tung, C., "Experimental and Analytical Studies of a Model Helicopter Rotor in Hover,"

NASA TM 81232.

[2] 1989, Lorber, P.F., Stauter, R.C. and Landgrebe, A.J., "A Comprehensive Hover Test of the Airloads and Airflow of a Extensively Instrumented Model Helicopter Rotor,"

Proceedings of the 45th American Helicopter Society Forum.

[3] 1991, Srinivasan, G.R., Raghavan, V. and Duque, E.P.N.,

"Flow Field Analysis of Modern Helicopter Rotors in Hover by Navier-Stokes Methods," International Technical Specialist Meeting Rotorcraft Acoustics and Rotor Fluid Dynamics.

[4] 1994, Ramachandran, K., Owen, S.J., Caradonna, F.X. and Moffitt, R.C., "Hover Performance Prediction Using CFD,"

Proceedings of the 50th American Helicopter Society Forum.

[5] 2005, Bhagwat, M.J., Moulton, M.A. and Caradonna, F.X.,

"Development of a CFD-based Hover Performance Prediction Tool for Engineering Analysis," Proceedings of the 61st American Helicopter Society Forum.

[6] 1994, Tung, C. and Lee, S., "Evaluation of Hover Performance Prediction Codes," Proceedings of the 50th American Helicopter Society Forum.

[7] 1996, Wake, B.E. and Baeder, J.D., "Evaluation of a Navier-Stokes Analysis Method for Hover Performance Prediction," Journal of American Helicopter Society, Vol.41, No.1.