Computational Fluid Dynamics Flow Field Solutions for a

Kinetic Energy (KE) Projectile With Sabot

by Karen R. Heavey, James DeSpirito, and Jubaraj Sahu

ARL-MR-572 September 2003 Approved for public release; distribution is unlimited.

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Army Research Laboratory Aberdeen Proving Ground, MD 21005-5066

ARL-MR-572 September 2003

Computational Fluid Dynamics Flow Field Solutions for a Kinetic Energy (KE) Projectile With Sabot

Karen R. Heavey, James DeSpirito, and Jubaraj Sahu

Weapons and Materials Research Directorate, ARL Approved for public release; distribution is unlimited.

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January 2002 May 2003 5a. CONTRACT NUMBER

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4. TITLE AND SUBTITLE

Computational Fluid Dynamics Flow Field Solutions for a Kinetic Energy (KE) Projectile With Sabot

5c. PROGRAM ELEMENT NUMBER

5d. PROJECT NUMBER

1L162618AH80 5e. TASK NUMBER

6. AUTHOR(S)

Karen R. Heavey, James DeSpirito, and Jubaraj Sahu

5f. WORK UNIT NUMBER

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

U.S. Army Research Laboratory ATTN: AMSRL-WM-BC Aberdeen Proving Ground, MD 21005-5066

8. PERFORMING ORGANIZATION REPORT NUMBER

ARL-MR-572

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

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12. DISTRIBUTION/AVAILABILITY STATEMENT

Approved for public release; distribution is unlimited.

13. SUPPLEMENTARY NOTES

14. ABSTRACT

A study was undertaken to investigate and analyze the flow field results produced by various computational solvers for a projectile of interest to the U.S. Army. Computational fluid dynamics (CFD) techniques were used to obtain numerical solutions for the flow field of a kinetic energy projectile with the original and a modified (experimental) sabot. Computed results were obtained at Mach 4.5 and a 0 angle of attack. Qualitative flow field features showed the pressure on the surface of the model as well as pressures in the flow field. The surface pressure data on the projectile were extracted from the solution files and compared. In all cases, the results were comparable. These results show the predictive capabilities of CFD techniques in the analysis of supersonic flow over projectiles with sabots. They also provide an insight into the software capabilities of several of the many tools available to research scientists in the field of CFD.

15. SUBJECT TERMS

computational fluid dynamics (CFD), projectile aerodynamics, projectile with sabot, structured and unstructured grids

16. SECURITY CLASSIFICATION OF: 19a. NAME OF RESPONSIBLE PERSON Karen R. Heavey

a. REPORT UNCLASSIFIED

b. ABSTRACT UNCLASSIFIED

c. THIS PAGE UNCLASSIFIED

17. LIMITATION OF ABSTRACT

UL

18. NUMBER OF PAGES

30

19b. TELEPHONE NUMBER (Include area code) 410-278-2916

Standard Form 298 (Rev. 8/98) Prescribed by ANSI Std. Z39.18

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Contents

List of Figures iv

List of Tables v

Acknowledgments vi

1. Introduction 1

2. Flow Solvers 1 2.1 ZNSFLOW Code...............................................................................................................1

2.2 CFD++ Code .....................................................................................................................2

2.3 FLUENT Code ..................................................................................................................3

3. Projectile and Model Geometry 4 3.1 Projectile System...............................................................................................................4

3.2 Computational Models ......................................................................................................4

4. Computational Meshes 5 4.1 ZNSFLOW Grids ..............................................................................................................5

4.2 CFD++ Grids.....................................................................................................................6

4.3 FLUENT Grids..................................................................................................................7

5. Results 8 5.1 Original Sabot....................................................................................................................8

5.2 Modified Sabot ................................................................................................................12

5.3 Force Comparison ...........................................................................................................16

5.4 Solver Differences ...........................................................................................................19

6. Conclusion 20

7. References 21

iv

List of Figures

Figure 1. Drawing of an M829A2 round. .......................................................................................4 Figure 2. Schematic of computational model. ................................................................................4 Figure 3. Computational model of original sabot. ..........................................................................5 Figure 4. Expanded view of sabot cup: original (left) and modified (right)..................................5 Figure 5. The 2-D structured mesh for original sabot.....................................................................6 Figure 6. Computational mesh for 3-D model with modified sabot. ..............................................7 Figure 7. Mach contours for 2-D ZNSFLOW. ...............................................................................9 Figure 8. Mach contours for 2-D CFD++. ......................................................................................9 Figure 9. Mach contours for 2-D FLUENT. .................................................................................10 Figure 10. Pressure contours for 2-D ZNSFLOW. .......................................................................10 Figure 11. Pressure contours for 2-D CFD++...............................................................................11 Figure 12. Pressure contours for 2-D FLUENT............................................................................11 Figure 13. Comparison of Cp along centerline for 2-D cases.......................................................12 Figure 14. Mach contours for 3-D ZNSFLOW. ...........................................................................13 Figure 15. Mach contours for 3-D CFD++. ..................................................................................13 Figure 16. Mach contours for 3-D FLUENT. ...............................................................................14 Figure 17. Pressure contours for 3-D ZNSFLOW. .......................................................................14 Figure 18. Pressure contours for CFD++......................................................................................15 Figure 19. Pressure contours for 3-D FLUENT............................................................................15 Figure 20. Surface pressure for 3-D CFD++. ...............................................................................16 Figure 21. Surface pressure for 3-D ZNSFLOW..........................................................................17 Figure 22. Surface pressure for 3-D FLUENT. ............................................................................17 Figure 23. Comparison of Cp along the projectile centerline for 3-D cases.................................18 Figure 24. Comparison of Cp along 60 plane for modified sabot...............................................18 Figure 25. Comparison of centerline Cp for original and modified sabot, CFD++ solutions. .....19

v

List of Tables

Table 1. Dimensions for structured grids........................................................................................6 Table 2. Elements for unstructured grids......................................