AIAA-2005-4499

Novel TVC system utilizing guide vanes with jet flap’s into a high efficiency compact nozzle

Dr. Erland Ørbekk* Nammo Raufoss AS, Raufoss Norway

41st AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit July 10 – 13, 2005 Tucson, AZ

Abstract

Nammo Raufoss AS (Nammo) has positive experience in using Computational Fluid Dynamics (CFD) for prediction and evaluation of different types of thrust vector systems (TVC), internal flow path design and prediction of flow losses in solid propellant rocket motors. Nammo has developed and tested different types of TVC systems the last years and has experienced that the use of advanced CFD solvers are of great importance with respect to design dimensioning and performance analyses. Our CFD code has been extended during our participation in the Norwegian Propulsion Technology Development Programme by including chemical reactions, boundary conditions for burning of solid propellants and particle flow models. This paper presents the integration of a novel TVC system utilizing guide vanes with jet flap’s into a high efficiency compact nozzle. The compact annular nozzle design is analyzed and efficiency comparisons are performed with motor firings. TVC performance and accuracy of analyses are shown for different TVC systems. The presented TVC system combines our experience of jet vane TVC and movable nozzle (SSSL) TVC. The resulting system utilizing guide vanes positioned to reduce flow losses is functioning as a movable nozzle wall. The system is characterized by simple integration, similar to traditional jet vane integration. The design is shown and described by analyses and compared with other traditional TVC systems.

Nomenclature CFD Computational Fluid Dynamic TVC Thrust Vector Control JV Jet Vane JVTVC Jet Vane Thrust Vector Control SSSL SuperSonic Split Line ECU Electronic Control Unit TVA Thrust Vector Actuation 6-DOF Six Degree of Freedom

* Section Manager, Engineering/Development Department, P.O. Box 162, N-2831 Raufoss, Norway / (erland.orbekk@nammo.com),

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41st AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit10 - 13 July 2005, Tucson, Arizona

AIAA 2005-4499

Copyright © 2005 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

AIAA-2005-4499

I. Introduction Nammo has positive experience in using Computational Fluid Dynamics (CFD) for prediction and evaluation of different types of thrust vector control (TVC) systems, internal flow path design and prediction of effective nozzles. This paper presents the TVC capability at Nammo, Missile products Division. TVC systems and advanced nozzle designs, both in production or evaluated in the internal technology program. The TVC and nozzle work have resulted in the study of a novel TVC system utilizing jet flaps as control surfaces. It should also be noted that the TVC with guide vanes and jet flaps is patent pending.

II. TVC Experience at Nammo Nammo has worked with TVC systems since mid 1990’s, and is presently involved in the design, development and production of different TVC systems. Nammo’s TVC experience is shortly summarized as:

• Technology program firings of JVTVC systems for JV material selections • Design, development and industrialized lightweight high performance TVC exit cone assembly for an air-

to-air application • Design and development of JVTVC for larger booster application • Design of light weight JVTVC for ground launch application • Technology program firings evaluating SSSL joint materials • Technology program firings using SSSL TVC • Design and firings of advanced compact nozzles • Design of dual nozzle SSSL systems

Figure 1 JVTVC material testing and initial SSSL test set up

III. TVC Design Tools

The most important TVC design tools with respect to TVC performances are shortly described in this chapter.

A. CFD Design Tool

The design tool we have been using is a CFD code can simulate 2D and 3D reacting rocket motor flows, containing an arbitrary number of solid particle groups. The CFD code has options for chemical equilibrium, chemical non-

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equilibrium, or frozen chemistry flows. Furthermore, it can be applied to inviscid or viscous flows, in the latter case the standard k-ε turbulence model is utilized. The burning propellant grain boundary condition is approximated as burning rate versus pressure, utilizing the formula of Saint Robert Vieille. The drag coefficient of the particles, condensed/solid phase, is based upon the formula of Crowe [1] and modified by Hermsen [2]. Empirical models based upon measurements are utilized for particle size definition. The CFD code has been utilized in several development programs and predicted results are in very good agreement with the performed motor firings.

B. TVC Math Model A math model has recently been developed at Nammo for TVC analyses and design evaluations. The math model includes the responses of the ECU and for the TVA, i.e. a simulation tool for the commands given by the missile computer with resulting responses of the rocket motor in all axes. Thus, the computer code is able to simulate live TVC’s. A layout of the model is shown in Figure 2. The model has been tested in existing development programmes. The model outputs in addition to the forces and moments; centre of gravity, moments of inertias, distances to aerodynamic centre of pressures, TVC responses, etc. The TVC simulations performed with this tool seem to be in excellent agreement with measured performances.

F1Theoretical thrust

without JV

F3Jet Vane

Deflection effects

F2Calculation of

Mass, CoG and Inertias

F5Thrust Forces and

MomentsAs function of

JV CoP and Pracox

F4Thrust

Forces and MomentsIn Missile

Axis

Input TVC Math Model OutputFx(t)

T

D_CoG (x,0,0)

(δcoi)

p

JV Data

Motor Data

(δEXi)

(δEXi)

(δEXi)

(δEXi)

Propellant Data Fx0, Fave, Isp,Itot

m

F0, Itot

Itot

•

• •

• Masses & m •

Motor CoG

Motor Inertias

Fx,Fy,Fz

Mx,My,Mz

D_CoGM (x,0,0)

JV CoP, etc

Motor ForcesOn Missile Level

Transformationof

x,y,zto

u,v,w

Figure 2 Math model for complete TVC

IV. Evaluation of Technology Programme Motors

4.1 Generic Type Motor with Jet Vanes Nammo has extensive experience in design and implementation of high performance lightweight JV based TVC systems, including testing of JV systems, both technology programs and full-scale development programs. The technology program with JVTVC is a 5” rocket motor. The jet vanes are integrated into the nozzle exit cone for minimum hinge moment (actuator forces) and for max overall aerodynamic performance. The CFD grid model with optimum JV integration into the nozzle exit cone and the test set-up of the technology motor is shown in Figure 3. Predictions and firings are compared and there are excellent agreement in between predictions and firing results, see Figure 4. The analyses utilize the TVC Math model, which includes model for the actuators responses. It can be

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seen that the plateau levels for side force and roll moment fits exactly with the measurements, meaning the JV aero coefficients are well defined. The model includes also erosion effects of the JV’s.

0 50 100XM

0

20

40

60

Figure 3 Integration of JVTVC in Nozzle Exit Cone, numerical model and test set-up

Time [sec]

Rol

l Mom

ent [

kNm

]

MeasuredJV Math Model

Time [sec]

Pitc

h An

gle

[°]

JV Math ModelMeasured

Figure 4 JVTVC CFD plot, roll moment and lateral force analyses and comparison with measurements 4.2 Generic Type Motor with SSSL Nozzle Nammo has performed CFD simulations and validations for motors utilizing the high performance SSSL technology. The SSSL technology is based upon a movable exit cone, i.e. movement of the supersonic exit cone only. The CFD calculation showed that it was possible to optimize for a higher thrust deflection value than the mechanical deflected nozzle angle. Thus, the amplification factor is defined as the ratio in between the thrust deflection angle and the mechanically positioned deflection angle. A test set-up and CFD model with results is shown in Figure 5. The CFD predicted performance fits excellent with the measured SSSL performance, see Figure 6. Amplification values in the region of 1.2 –1.4 is possible to achieve for SSSL systems.

X

Y

Z

0 50 100X [m m ]

-20

-10

0

10

20

30

40

50

60

70

80

90

100

Y[m

m]

AM

3.23 .02 .82 .62 .42 .22 .01 .81 .61 .41 .21 .00 .80 .60 .40 .20 .0

S S S L, 3 D C F D a na lysis

N oz z le de flection 1 5 degre esM ach num be r contours [-]

Figure 5 View of SSSL test motor, CFD grid and CFD solution

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0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

0 2 4 6 8 10Nozzle Deflection Angle [degrees]

Am

plifi

catio

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ctor

[-]

12

Amplification Factor [-]

0.00

0.20

0.40

0.60

0.80

1.00

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2.00

0.0 2.0 4.0 6.0 8.0 10.0 12.0Commanded alfa y direction [degrees]

Am

plifi

catio

n Fa

ctor

[-]

fy ratio

Figure 6 Calculation and measured SSSL amplification factor

V. Validation and Test Capability

TVC designs can be validated at Nammo through comparison with firing results in the in house 6-DOF test bench. A set-up of the test bench is shown in Figure 7. The 6_DOF cell with installed motor to the left in the picture. The Nammo test bench consists of a KISTLER Dynamometer, horizontally mounted. An aft end side force fixture is normally utilized for increased measurement accuracy.

Figure 7 6-DOF Test Bench at Nammo

VI. Advanced Short Nozzles

Nammo participates and has participated in different Hypervelocity missile programs. Different nozzle concepts were studied in order to maximize the total impulse into the rocket motor envelope. The resulting nozzles are characterized by being short, large expansion ratios nozzles with a double expansion ramp, i.e. an annular nozzle type. An example design is shown in Figure 8. The nozzle plug (center piece) is kept in place by a spoke wheel system. The spokes are implemented into the design for minimum thrust loss, i.e. leading edge is located in the low subsonic flow domain. The spokes are designed as

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airfoils. Flow analyses, mechanical structure tests and motor firing tests have been performed on technology motors, see example in Figure 9. The firing tests performed in the technology programme showed excellent performance with respect to erosion and nozzle performance. Spoke wheel induced loss was negligible. The overall nozzle efficiency is comparable with more traditional nozzles. The nozzle exit cone length can be heavily reduced compared to traditional nozzles. Such a nozzle is successfully introduced in a booster development programme at Nammo, see Figure 10 and Figure 11. The booster total impulse, within the given system envelope, was increased by the introduction of the short annular nozzle. The predicted nozzle efficiency and the firing results are in excellent agreement.

side 8M I S S I L E P R O D U C T S D I V I S I O N

Hyper Velocity Programs

New hyper velocity technologyis under development for next generation missile systems.

Nammo Raufoss is involved in two different programs.

•One with Annular Nozzle

•One with Quasi Annular Nozzle

Figure 8 Hypervelocity program and introduced double expansion type short nozzles, the HVM at left was with a traditional nozzle exit cone

Figure 9 Material and erosion test of nozzle plug support

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AM3.232.82.62.42.221.81.61.41.210.80.60.40.20

Figure 10 CFD predictions of annular nozzle type system

e

Figure 11 Booster utilizing the annular no

The successful testing of the short annularwhen starting the principal design work of a Missile system requirements are often chrequired to be implemented as dual type relatively heavy to integrate. The SSSL ssystems, see Figure 12 right is characterize“Novel TVC” was to combine these two sol The jet vane induced thrust loss is dominateis influenced by the bow shock. Thus, a principal design is shown in Figure 13 (le(guide vane) positioned upstream of the flap The spoke wheel, presented in the previous itself can be fixed to the nozzle, supersonicsliding type bearings or ball type bearings. vane, and the hinge moment for the intetraditional JV systems. However, the integr

American I

Firing of booster nozzl

zzle, nozzle seen before and after firing

VII. Novel TVC

nozzle and our experience in TVC technology was important factors “Novel TVC system utilizing jet flaps “.

aracterized by having roll requirement. SSSL type nozzles are often nozzle systems, see Figure 12 left. Such systems are expensive and ystem is characterized by very low flow losses. Traditional JVTVC

d by high thrust losses, but are relative easy to integrate. The idea of the utions into one system having the performance benefits of both.

d by the leading edge bow shock, i.e. both the zero drag and alpha drag jet vane design similar to the movable SSSL walls was studied. The ft). The leading edge of the jet vane (flap) is protected by a static fin .

chapter, can be used as the guide vane by extending the length. The flap part, at both ends, i.e. at the nozzle outer wall and at the plug wall by The hinge line for the flap will be positioned downstream of the guide gration are foreseen to be much greater than the hinge moment for ation will eliminate the bending forces in the JV blade (root), which is

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often a design challenge for traditional JV designs. By the integration, the leading edge is protected and traditional JV erosion is probably more or less eliminated. The need of sophisticated JV materials is reduced. The integration of the guide-vane flap system is comparable with the integration of a traditional JV system. The TVC with guide vanes and flaps is shown in detail in Figure 14. Different combinations of side thrust are seen on the plots.

Figure 12 Dual type SSSL TVC system(left) and JVTVC system (right)

Throat area

Supersonc area

Fin inlet positionedin subsonic area, i.e.Minimized leading edgeloss

Static finswill only increasenozzle wall area,i.i wetted area

JV located downstream of static fin, i.e pressure inducedloss at zero deflection is negligible

Subsonic area(Motor chamber)

Part of Nozzle Structure JV

Prandtl MeyerExpansionand reduced pressure

CompresionFlow from Chamber

Throat area

Flow from Chamber

Figure 13 Principal sketch of “Novel TVC”

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Figure 14 Implementation of JV flap system into a short double expansion type nozzle (Pat. pending)

VIII. Performance Evaluation

The Novel TVC system utilizing guide vanes with jet flaps has been integrated into a high efficiency compact nozzle, generic type in order to evaluate the performance for such a TVC integration. The geometry model is shown in form of the CFD grid in Figure 15. The grid is shown from the motor inside on left, i.e. the low velocity region, and on right the grid is shown from motor aft. All flaps are positioned in Zero degrees. The grid utilized, covering a sector of 180° and consists of 417723 grid points. CFD analyses are performed at 0° deflected fins and at 20° deflected fins. The forces have been calculated, and effects of nozzle, i.e. damping of forces is included in the presented results. Results for the nozzle is plotted in Figure 16 and Figure 17 for flaps positioned in 0° and 20°. Plot view from motor inside to the left and view from motor aft to the right in both figures. The pressure on the guide vane and flap is smoothly decreasing with the nozzle expansion for the 0° simulation. No pressure wave reflections or indications of pressure loss can be observed. The pressure on the flap is compressed as the flow hits the oblique ramp with flap positioned in 20°. The peak pressure on the pressure side is in the region of p/p0≈0.2 [-]. The expansion on the suction side reduces the pressure to be at the lowest p/p0≈0.004 [-]. Pressure at Nozzle exit is in the region of p/p0≈0.025 [-] The resulting side thrust angle for the simulated TVC utilizing guide vanes with flaps was 7°. The flaps are slightly larger than traditional jet vanes. Larger thrust deflection angles should be obtainable by optimizing the flap position and size. The calculated thrust loss at a 7° thrust deflection is very low, approximately 20% of the loss compared to traditional JV systems. The loss is closer to the typical losses for SSSL systems. The thrust loss vs flap deflection is

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compared with a typical traditional JV system in Figure 19. Both system are capable of a 7° thrust deflection at full JV/flap deflection. Actuator requirements are, due to the hinge line position, increased compared to traditional JV systems. However, the actuator force seems to be well below SSSL type actuator demands, even taking into account that flap system has be moved approx three times in angle compared to the SSSL moved the angle.

t

Figur

Figur

Throa

Jet Flap Hinge Line

e p

e 15 CFD Grid of TVC n

e 16 CFD solution, plots

Inlet Guide Van

ozzle utilizing flaps, seen from

LOG10 (PSTAT)

of static pressure, log10 functi

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Guide vane

Jet Fla

motor chamber (inside) and from aft

LOG10 (PSTAT)

on. Flaps positioned in 0°

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LOG10 (PSTAT)

LOG10 (PSTAT)

Figure 17 CFD solution, plots of static pressure, log10 function. Flaps positioned in 20°

e

e

e

Figure 18 CFD solutio

Guide vane

n, plot of

Hinge Lin

Mach number along guide vane w

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Suction Sid

Pressure Sid

ith jet flap, pressure side and suction side

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0

2

4

6

8

10

12

14

0 5 10 15 20 25JV/Flap Deflection Angle

Thru

st L

oss [

%]

Loss JV, initial burnLoss JV, end of burnLoss guide vane w/ flaps

Figure 19 Typical thrust loss of a traditional JV system vs the presented guide vane w/ jet flap system

IX. Conclusion

The TVC design tools applied at Nammo are validated in different TVC systems and shows excellent agreement with test results of different designs. The Aerodynamic effects are predicted at a high level of confidence and the new math model for TVC performance analyses are in excellent agreement with performed TVC motor firings. The analyzed performance of the “Novel TVC utilizing guide vanes with jet flaps” is a promising candidate for further studies. The lateral thrust and roll moment are close to what is possible with traditional JV systems. The thrust-induced loss is more or less negligible compared to traditional JV systems. The design integration is as simple as for traditional JV systems and the integration can be made as a lightweight component. Actuator forces would normally to be less than required for SSSL type systems. It should also be noted that the TVC with guide vanes and jet flaps is patent pending.

Acknowledgments This work has been financed by our participation in the Norwegian Propulsion Technology Development Program, initiated in 1997.

References

[1] Crowe, C. T., “Drag Coefficient of Particles in a Rocket Nozzle”, AIAA Journal, 5, 1021-1022, 1967. [2] Hermsen, R. W., “Review of Particle Drag Models,” JANNAF Performance Standardization Subcommittee, 12th Meeting Minutes, January 1979.

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[3] Schaff, S., P. Chambre, “Flow of rarefied Gases,” in Fundamentals of Gas Dynamics, Princeton Series, Vol. III, Princeton University Press, 1958. [4] B. McBride, S. Gordon, M. Reno, CETPC/93, “ Chemical Equilibrium with Transport Properties, 1993”, COSMIC Program # LEW-16017, Lewis Research Center, Cleveland, Ohio. [5] SPP, A Computer Program for the Predictions of Solid Propellant Rocket Motor Performance, Software and Engineering Associates Inc., Carson City, Ne

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