Abstract
In the field of external ballistics, the geometry (shape and structure) of the projectile plays a significant role. This geometry affects a multitude of variables, including air resistance, stability, range, and accuracy. The objective of this study was to decrease the drag coefficients by making different geometric alterations to the Spitzer-type ogive bullet and examining the flow conditions, Mach number, and pressure distributions around the projectile using a three-dimensional numerical simulation. Upon examination of the results, it was observed that the flow exhibited subsonic stagnation zones and a velocity drop upstream of the nose tip. The flow became slightly supersonic as it expanded around the ogive nose and boattail junction. Expansion fans and recompression shocks were detected at the points where the ogive-shaped nose of the projectile transitions to the body, where the boattail-shaped rear of the projectile transitions to the body, and at the base of the projectile. The pressure coefficient value reached its maximum value of CP=0.7 when the air decelerated and dropped to CP=-0.5 as the projectile transitioned from the nose to the body. A gradual decrease in pressure along the projectile surface resulted in a more consistent and lower pressure coefficient compared to the nose. The A3-type bullet, including the most extensive spiral groove, exhibited a 12.4% enhancement in drag reduction as compared to the original bullet. The B-series of straight grooves exhibited a considerable decrease in drag. Nevertheless, the efficacy of helical grooves in regulating flow separation at the tail surpassed that of other methods. The A-series bullets, namely A2 and A3, were well-suited for applications that demanded little aerodynamic resistance. The B-series bullets exhibited enhancements compared to the conventional design and may be deemed suitable for more straightforward production or design limitations.
Keywords
Supporting Institution
TUBITAK
Project Number
1919B012109748
Thanks
The authors would like to thank TUBITAK (The Scientific and Technological Research Council of Turkey) (Project number: 2209-A-1919B012109748) for their financial support.
References
- R. L. McCoy, Modern Exterior Ballistics. Schiffer Military History, 2012.
- A. Ferfouri, T. Allouche, D. D. Jerković, N. Hristov, M. Vučković, and A. Benmeddah, “Prediction of drag aerodynamic coefficient of the 155mm projectile under axisymmetric flow using different approaches,” Journal of the Serbian Society for Computational Mechanics, vol. 17, no. 2, pp. 69–86, Dec. 2023.
- S. Sahoo and M. K. Laha, “Coefficient of Drag and Trajectory Simulation of 130 mm Supersonic Artillery Shell with Recovery Plug or Fuze,” Defence Science Journal/Defence Science Journal, vol. 64, no. 6, pp. 502–508, Nov. 2014.
- T. Gholap, R. Salokhe, G. Ghadage, S. Mane, and D. Sahoo, “Aerodynamic analysis of an AK-47 bullet moving at mach 2.0 in close proximity to the ground,” FME Transactions, vol. 50, no. 2, pp. 369–381, Jan. 2022.
- S. Selimli, “Yüzey geometrisinin mermi aerodinamik davranışları üzerine etkisinin nümerik incelenmesi”, Politeknik Dergisi, 24(1), 299-304, 2021.
- D. S. K. Reddy, P. K. Sah, and A. Sharma, “Prediction of Drag Coefficient of a Base Bleed Artillery Projectile at Supersonic Mach number,” Journal of Physics. Conference Series, vol. 2054, no. 1, p. 012013, Oct. 2021.
- A. Khan, I. Shah, S. Aziz, M. Waqas, U. K. U. Zaman, and D.-W. Jung, “Numerical and Experimental Analysis of Drag and Lift Forces on a Bullet Head,” Aerospace, vol. 9, no. 12, p. 816, Dec. 2022.
- C. Gan “Computational Fluid Dynamics (CFD) of Drag Force for Bullet’s Shape Design.” In Journal of Physics: Conference Series , Vol. 1888, No. 1, p. 012016
- S. Salunke, S. Shinde, T. Gholap, and D. Sahoo, “Comparative computational analysis of NATO 5.56 mm, APM2 7.62 mm and AK-47 7.82 mm bullet moving at Mach 2.0 in close vicinity to the wall,” FME Transactions, vol. 51, no. 1, pp. 81–89, Jan. 2023.
- S. Serdarevic-Kadic and J. Terzic, “Effects of Base Shape to Drag at Transonic and Supersonic Speeds by CFD,” in DAAAM international scientific book, pp. 071–080, 2019.
- B. Litz, Applied Ballistics for Long-Range Shooting, 2nd ed., Applied Ballistics LLC, 2011.
- Larson, E., Lwali, R., & Samardzic, D. (2015). Bullet drag estimation with compressible conical flow equations and commercial software. Department of Aerospace Engineering and Engineering Mechanics, San Diego State University research.
- I. Asproulias, “RANS modelling for compressible turbulent flows involving shock wave boundary layer interactions,” PhD Thesis, UK: The University of Manchester, 2014.
- https://www.afs.enea.it/project/neptunius/docs/fluent/html/th/node421.htm [Online]. Available, [Accessed: 31-May-2024].
- P. Spalart and S. Allmaras, “A one-equation turbulence model for aerodynamic flows,” 30th Aerospace Sciences Meeting and Exhibit, Jan. 1992.
Mermide Geometrik Değişiklikler Yoluyla Sürüklemenin Azaltılmasının Hesaplamalı Akışkanlar Dinamiği Analizi
Abstract
Dış balistik alanında, merminin geometrisi (şekli ve yapısı) önemli bir rol oynar. Bu geometri hava direnci, stabilite, menzil ve isabetlilik gibi çok sayıda değişkeni etkilemektedir. Bu çalışmada, Spitzer tipi ogive mermisine çeşitli geometrik modifikasyonlar uygulayarak sürükleme katsayılarını azaltmak amacıyla üç boyutlu bir sayısal simülasyon gerçekleştirilmiştir. Sayısal modelleme amacıyla ANSYS Fluent paketi kullanılmış ve farklı Mach sayıları için mermi üzerindeki sürükleme katsayısı ve mermi etrafındaki akış koşulları, hız ve basınç dağılımları incelenmiştir. Analiz edilen tüm mermiler, akışın olmadığı ses altı bir bölge ve burun ucunun yukarısında hızda bir azalma ile eksenel simetrik özelliklere sahipti. Hava akışı, oval burun ile tekne kuyruğu arasındaki birleşme noktasında ses hızının biraz üzerinde bir hıza ulaşmıştır. Bu durum, kovan ile gövde, tekne kuyruğu ile gövde ve merminin tabanı arasındaki geçişlerde genişleme fanlarının ve yeniden sıkıştırma şoklarının oluşmasına neden olmuştur. Merminin orta kısmındaki basınç dağılımı neredeyse simetriktir, düşük basınç alanları merminin etrafında odaklanmış ve yüksek basınç alanları hem yukarı hem de aşağı yönde yayılmıştır. Oluşturulan tüm mermiler, orijinal mermiye kıyasla daha düşük sürükleme katsayısı değerlerine sahipti. A3 tipi mermi 0.288 ile en düşük değere sahipti. Bununla birlikte, ilk mermi ile karşılaştırıldığında sürüklemede %12,4'lük kayda değer bir artış elde edilmiştir.
Project Number
1919B012109748
References
- R. L. McCoy, Modern Exterior Ballistics. Schiffer Military History, 2012.
- A. Ferfouri, T. Allouche, D. D. Jerković, N. Hristov, M. Vučković, and A. Benmeddah, “Prediction of drag aerodynamic coefficient of the 155mm projectile under axisymmetric flow using different approaches,” Journal of the Serbian Society for Computational Mechanics, vol. 17, no. 2, pp. 69–86, Dec. 2023.
- S. Sahoo and M. K. Laha, “Coefficient of Drag and Trajectory Simulation of 130 mm Supersonic Artillery Shell with Recovery Plug or Fuze,” Defence Science Journal/Defence Science Journal, vol. 64, no. 6, pp. 502–508, Nov. 2014.
- T. Gholap, R. Salokhe, G. Ghadage, S. Mane, and D. Sahoo, “Aerodynamic analysis of an AK-47 bullet moving at mach 2.0 in close proximity to the ground,” FME Transactions, vol. 50, no. 2, pp. 369–381, Jan. 2022.
- S. Selimli, “Yüzey geometrisinin mermi aerodinamik davranışları üzerine etkisinin nümerik incelenmesi”, Politeknik Dergisi, 24(1), 299-304, 2021.
- D. S. K. Reddy, P. K. Sah, and A. Sharma, “Prediction of Drag Coefficient of a Base Bleed Artillery Projectile at Supersonic Mach number,” Journal of Physics. Conference Series, vol. 2054, no. 1, p. 012013, Oct. 2021.
- A. Khan, I. Shah, S. Aziz, M. Waqas, U. K. U. Zaman, and D.-W. Jung, “Numerical and Experimental Analysis of Drag and Lift Forces on a Bullet Head,” Aerospace, vol. 9, no. 12, p. 816, Dec. 2022.
- C. Gan “Computational Fluid Dynamics (CFD) of Drag Force for Bullet’s Shape Design.” In Journal of Physics: Conference Series , Vol. 1888, No. 1, p. 012016
- S. Salunke, S. Shinde, T. Gholap, and D. Sahoo, “Comparative computational analysis of NATO 5.56 mm, APM2 7.62 mm and AK-47 7.82 mm bullet moving at Mach 2.0 in close vicinity to the wall,” FME Transactions, vol. 51, no. 1, pp. 81–89, Jan. 2023.
- S. Serdarevic-Kadic and J. Terzic, “Effects of Base Shape to Drag at Transonic and Supersonic Speeds by CFD,” in DAAAM international scientific book, pp. 071–080, 2019.
- B. Litz, Applied Ballistics for Long-Range Shooting, 2nd ed., Applied Ballistics LLC, 2011.
- Larson, E., Lwali, R., & Samardzic, D. (2015). Bullet drag estimation with compressible conical flow equations and commercial software. Department of Aerospace Engineering and Engineering Mechanics, San Diego State University research.
- I. Asproulias, “RANS modelling for compressible turbulent flows involving shock wave boundary layer interactions,” PhD Thesis, UK: The University of Manchester, 2014.
- https://www.afs.enea.it/project/neptunius/docs/fluent/html/th/node421.htm [Online]. Available, [Accessed: 31-May-2024].
- P. Spalart and S. Allmaras, “A one-equation turbulence model for aerodynamic flows,” 30th Aerospace Sciences Meeting and Exhibit, Jan. 1992.
Details
| Primary Language | English |
|---|---|
| Subjects | Aerodynamics (Excl. Hypersonic Aerodynamics), Computational Methods in Fluid Flow, Heat and Mass Transfer (Incl. Computational Fluid Dynamics), Turbulent Flows |
| Journal Section | Research Articles |
| Authors | |
| Project Number | 1919B012109748 |
| Early Pub Date | June 28, 2024 |
| Publication Date | June 30, 2024 |
| Submission Date | May 31, 2024 |
| Acceptance Date | June 26, 2024 |
| Published in Issue | Year 2024 Volume: 7 Issue: 1 |
