Mermi Hareketinin Modellenmesinde Kullanılan Noble-Abel ve İdeal Gaz Denklemlerinin Akış Alanına Etkisinin Nümerik İncelenmesi

Öz

Gelişen malzeme ve üretim teknolojileri ile birlikte silahlar küçülmeye başlamış ve bu problem büyük oranda çözülmüştür. Ancak silahlardan temel olarak elde edilmek istenen yüksek yıkım etkisidir. Bu durum günümüzde halen en önemli problemlerden birisi olan geri tepme kuvvetini de beraberinde getirmekte ve incelenmesi gereken bir konu olarak güncelliğini sürdürmektedir. Bir ateşli silahta geri tepme kuvveti barutun yanmasına bağlı olarak ortaya çıkan gazın basıncından kaynaklanır. Bu anlamda ateşli silah namlusunda hareket eden bir merminin etrafındaki akış alanının tahmin edilmesi gerekir ki bu oldukça karmaşık bir iştir. Karmaşıklıklar, türbülans, karmaşık yüzey geometrisi, hesaplama alanındaki zaman değişikliği, sıkıştırılabilirlik ve gaz denklemleri gibi çok sayıda faktörün varlığından kaynaklanmaktadır. Bu çalışma kapsamında yanma sonucu olan gazların davranışının modellenmesinde kullanılan Noble-Abel ve ideal gaz denklemlerinin, merminin akış alanı üzerindeki etkisi nümerik olarak incelenmiştir. Nümerik modellemede Fluent paket programı kullanılmıştır. Hesaplamalar iki boyutlu, kararsız, sıkıştırılabilir, eksenel simetrik şartlarda gerçekleştirilmiştir. Hesaplamalar sonucunda mermi etrafında oluşan basınç dağılımı, namlu ekseninden farklı konum boyunca çizilmiş ve bu konumlarda farklı zaman değerleri için basınç değerleri gösterilmiştir.

Anahtar Kelimeler

• Nümerik modelleme
• Dinamik analiz
• Mermi
• Namlu
• Akış alanı

Numerical Investigation of the Effects of Noble-Abel and Ideal Gas Equations Used in the Modeling of Projectile Movement on the Flow Field

Abstract

With the developing materials and manufacturing technologies, the guns started to get smaller and this problem was solved to a large extent. However, what is basically desired to be obtained from the guns is the high destruction effect. This situation brings with it the recoil force, which is still one of the most important problems today, and continues to be a topic that needs to be examined. In a gun, the recoil force is due to the pressure of the gas that occurs due to the combustion of gunpowder. In this sense, it is necessary to estimate the flow field around a projectile moving in a firearm barrel, which is a very complex phenomena. The complexities are due to the presence of a large number of factors, such as turbulence, complex surface geometry, time change in the computational domain, compressibility, and gas equations. In this study, the effect of Noble-Abel and ideal gas equations, which are used in modelling the behaviour of combustion gases, on the flow field of the projectile was investigated numerically. Fluent program was used in numerical modelling. Calculations were carried out in two-dimensional, transient, compressible, axisymmetric conditions. As a result of the calculations, the pressure distribution around the projectile was drawn along a position different from the barrel axis, and pressure values were shown for different time values at these positions.

Keywords

• Numerical modelling
• Dynamic analysis
• Projectile
• Barrel
• Flow region

Kaynakça

1. Bournot, H., Daniel, E., & Cayzac, R. (2006). Improvements of the base bleed effect using reactive particles. International Journal of Thermal Sciences, 45(11), 1052–1065. https://doi.org/https://doi.org/10.1016/j.ijthermalsci.2006.01.018
2. Carson, R. A., & Sahni, O. (2014). Numerical investigation of propellant leak methods in large-caliber cannons for blast overpressure attenuation. Shock Waves, 24(6), 625–638. https://doi.org/10.1007/s00193-014-0522-7
3. Cler, D., Chevaugeon, N., Shephard, M., Flaherty, J. E., & Remacle, J.-F. (2003). CFD application to gun muzzle blast--a validation case study. 41st AIAA Aerospace Sciences Meeting and Exhibit.
4. Danberg, J. E., & Nietubicz, C. J. (1992). Predicted flight performance of base-bleed projectiles. Journal of Spacecraft and Rockets, 29(3), 366–372. https://doi.org/10.2514/3.26360
5. Fansler, K. S., & Schmidt, E. M. (1978). Trajectory perturbations of asymmetric fin-stabilized projectiles caused by muzzle blast. Journal of Spacecraft and Rockets, 15(1), 62–64. https://doi.org/10.2514/3.27998
6. Jiang, X.-H., Fan, B.-C., & Li, H.-Z. (2008). Numerical investigation on the muzzle flow with dynamic mesh based on ALE equation. Jisuan Lixue Xuebao/Chinese Journal of Computational Mechanics, 25, 563–567.
7. Jiang, X., Fan, B., & Li, H. (2008). Numerical investigations on dynamic process of muzzle flow. Applied Mathematics and Mechanics, 29, 351–360. https://doi.org/10.1007/s10483-008-0306-y
8. Jiang, Z. (2003). Wave dynamic processes induced by a supersonic projectile discharging from a shock tube. Physics of Fluids, 15(6), 1665–1675. https://doi.org/10.1063/1.1566752

9. Jiang, Z., Huang, Y., & Takayama, K. (2004). Shocked flows induced by supersonic projectiles moving in tubes. Computers & Fluids, 33(7), 953–966. https://doi.org/https://doi.org/10.1016/S0045-7930(03)00041-0
10. Le, G., Ma, D., Feng, Y., Shi, G., Zhu, Z., & Song, X. (2004). Numerical simulation of muzzle blast flowfields of large caliber guns. 25, 19–22.
11. Luo, Y., Xu, D., & Li, H. (2020). Analysis of the Dynamic Characteristics of the Muzzle Flow Field and Investigation of the Influence of Projectile Nose Shape. Applied Sciences , Vol. 10. https://doi.org/10.3390/app10041468
12. Mathur, T., & Dutton, J. C. (1996). Base-Bleed Experiments with a Cylindrical Afterbody in Supersonic Flow. Journal of Spacecraft and Rockets, 33(1), 30–37. https://doi.org/10.2514/3.55703
13. Xavier, S. (2011). Numerical Analysis of Gun Barrel Pressure Blast Using Dynamic Mesh Adaption.
14. Zhuo, C., Feng, F., Wu, X., Liu, Q., & Ma, H. (2014). Numerical simulation of the muzzle flows with base bleed projectile based on dynamic overlapped grids. Computers & Fluids, 105, 307–320. https://doi.org/https://doi.org/10.1016/j.compfluid.2014.08.006