Fluid Dynamics最新文献_第3页

Computational Analysis of an AK-47 Bullet Proximate to Stationary, Moving, and Porous Wall AK-47子弹接近静止、移动和多孔壁的计算分析

IF 0.6 4区工程技术

Fluid Dynamics Pub Date : 2025-09-03 DOI: 10.1134/S0015462825600944

K. R. Kandula, Y. Parkhi, T. Gholap, D. Sahoo

{"title":"Computational Analysis of an AK-47 Bullet Proximate to Stationary, Moving, and Porous Wall","authors":"K. R. Kandula, Y. Parkhi, T. Gholap, D. Sahoo","doi":"10.1134/S0015462825600944","DOIUrl":"10.1134/S0015462825600944","url":null,"abstract":"In firearms and ballistics, grasping the interaction between high-speed projectiles and their surroundings is crucial for optimizing trajectory, stability, and accuracy. This study explores the comparison of intricate flow dynamics involved when a bullet, traveling at the Mach number equal to 2, is fired near both a moving object or wall and a stationary wall, particularly in urban warfare scenarios. The proximity to the wall introduces an asymmetry in the pressure distribution across the bullet’s body, affecting its flow physics in diverse ways. The present analysis employs Computational Fluid Dynamics to scrutinize the flow field around a 7.82-mm bullet from an AK-47 rifle moving at supersonic speeds near the ground. Computational simulations explore phenomena at various heights from a nearby stationary or moving wall, ranging from the region of nearest influence to a ground distance five times the bullet’s diameter. The study encompasses height-to-diameter ratios h/D from 0.5 to 5, shedding light on the overall flow field, the pressure coefficient distributions, and the lift, drag, and moment coefficients. Additionally, the flow field in the wake region is examined. The results highlight the generation of a detached bow shock wave at the bullet’s tip, significantly influencing the drag coefficient experienced by the projectile. This study contrasts the effects of a stationary wall at varying proximities to the ground with those of a moving wall at equivalent distances. The comparison highlights change in flow characteristics and various parameters, providing valuable insights into high-speed projectiles in proximity to stationary walls and moving walls simultaneously (h/D) at a Mach number 2 during urban warfare scenarios. Furthermore, a study on the effect of porous wall proximity to the bullet has been conducted, and the shock absorption reduces the momentum. Understanding these phenomena is crucial for optimizing the bullet design and enhancing the effectiveness of missile ballistics in real-world applications.","PeriodicalId":560,"journal":{"name":"Fluid Dynamics","volume":"60 4","pages":""},"PeriodicalIF":0.6,"publicationDate":"2025-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144934606","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Effect of Air Tab Orientation on the Mixing and Spreading Characteristics of a Subsonic Jet 气片方向对亚音速射流混合与扩散特性的影响

IF 0.6 4区工程技术

Fluid Dynamics Pub Date : 2025-09-03 DOI: 10.1134/S0015462825600518

R. Arun Prasad, S. Ilakkiya, N. Krishna, K. Dhamodaran, S. Thanigaiarasu

{"title":"Effect of Air Tab Orientation on the Mixing and Spreading Characteristics of a Subsonic Jet","authors":"R. Arun Prasad, S. Ilakkiya, N. Krishna, K. Dhamodaran, S. Thanigaiarasu","doi":"10.1134/S0015462825600518","DOIUrl":"10.1134/S0015462825600518","url":null,"abstract":"The aim of this experimental study is to investigate the influence of air tab orientation on the mixing and spreading behavior of a Mach 0.8 primary jet ejected from an axisymmetric nozzle. Two air tabs have been considered in two configurations, namely, 90° and 45°, with respect to the primary jet centerline. The air tab Mach numbers, ranging from 1.1 to 1.4 in an interval of 0.1, have been considered. The jet decay along the primary jet centerline (X), along the lateral (Y), and vertical (Z) directions have been acquired. The jet half-width also has been calculated to assess the mixing/spreading enhancement induced by air tabs along the lateral and vertical directions. The percentage reduction in potential core achieved by 90° air tabs is higher than that of the 45° air tabs at all the Mach numbers studied. The 90° air tabs contract the primary jet along the vertical direction and expand it along the lateral direction. This implies a better jet mixing enhancement in the vertical direction and improves spreading along the lateral direction. On the other hand, the 45° air tabs result in rapid jet decay along both directions, in the far-field locations. The present study reveals that the 90° air tabs are best suited for applications that require better jet mixing, while the 45° air tabs are suitable for moderate jet mixing with the minimum total pressure loss.","PeriodicalId":560,"journal":{"name":"Fluid Dynamics","volume":"60 4","pages":""},"PeriodicalIF":0.6,"publicationDate":"2025-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144934713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Dynamics of the Development of the Hydraulic Fracture near Injector in a Formation with Account for Sedimentation of Disperse Particles near Its Boundaries 考虑边界附近分散颗粒沉降的地层注水井附近水力裂缝发育动力学

IF 0.6 4区工程技术

Fluid Dynamics Pub Date : 2025-07-30 DOI: 10.1134/S0015462824604558

D. P. Meteleva, A. Ya. Gil’manov, A. P. Shevelev

引用次数: 0

Experimental Investigation of the Mechanisms of Spontaneous Bending of a Viscous Jet 粘性射流自发弯曲机理的实验研究

IF 0.6 4区工程技术

Fluid Dynamics Pub Date : 2025-07-30 DOI: 10.1134/S0015462824605515

A. A. Safronov, A. A. Koroteev, A. E. Agafonov, A. L. Grigor’ev, N. I. Filatov, A. V. Khlynov

引用次数: 0

Gasdynamic Modeling of High-Temperature Siliconizing of Porous Silicon-Based Materials 多孔硅基材料高温硅化气动力学模拟

IF 0.6 4区工程技术

Fluid Dynamics Pub Date : 2025-07-30 DOI: 10.1134/S001546282460528X

V. A. Demin, S. A. Igoshev

引用次数: 0

Investigation on Mixing Behavior of Seeping Gas Film in Supersonic Boundary Layer Based on Acetone Planar Laser-Induced Fluorescence 基于丙酮平面激光诱导荧光的超声速边界层渗流气膜混合行为研究

IF 0.6 4区工程技术

Fluid Dynamics Pub Date : 2025-07-30 DOI: 10.1134/S001546282460559X

Q. Mi, S. K. Chen, S. H. Yi, D. D. Gang, F. Yuan

{"title":"Investigation on Mixing Behavior of Seeping Gas Film in Supersonic Boundary Layer Based on Acetone Planar Laser-Induced Fluorescence","authors":"Q. Mi, S. K. Chen, S. H. Yi, D. D. Gang, F. Yuan","doi":"10.1134/S001546282460559X","DOIUrl":"10.1134/S001546282460559X","url":null,"abstract":"Porous media seepage flow is the active flow control method used to reduce heat and skin friction in high-speed vehicles, but effective measurement techniques for mixing the seeping gases with the incoming boundary layer are lacking. By premixing approximately 20% acetone vapor in the cooling gas and employing the acetone planar laser-induced fluorescence (PLIF) technology, flow of the seeping gas film within the boundary layer was visualized. A correlation between the relative intensity of PLIF image grayscale and the gas film mixing rate is established. Experimental results showed that the seeping gas film layer remains initially laminar in the Mach 3 laminar boundary layer; with the lower injection rate, the film layer develops slowly and maintains a longer laminar state. As the injection rate increases, the film layer thickens significantly along streamwise direction on the porous wall. After reaching a certain thickness, instability develops, leading to intensified mixing with the incoming boundary layer downstream and the formation of large-scale mixing structures. The position of instability moves upstream with increase in the injection rates, indicating that the higher film injection rates tend to induce boundary layer instability and premature transition. When the injection rate F < 0.2%, the diffusion rate of the seeping gas film into the outer boundary layer is low, and the film maintains a high concentration at the bottom of the boundary layer. With the higher injection rates, the mixing ratio increases and diffuses outward, with a slight decrease in the normal concentration gradient of the film along the wall. For a given injection rate, the diffusion range of the seeping gas film continuously increases but does not exceed 5 mm in thickness. The study shows that the acetone PLIF technology can effectively achieve fine visualization and quantitative analysis of the mixing flow structures of seeping gases within supersonic boundary layers.","PeriodicalId":560,"journal":{"name":"Fluid Dynamics","volume":"60 2","pages":""},"PeriodicalIF":0.6,"publicationDate":"2025-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145171476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Numerical Simulation of Hyperelastic Sphere Water Entry Influenced by Surface Features 地表特征对超弹性球入水影响的数值模拟

IF 0.6 4区工程技术

Fluid Dynamics Pub Date : 2025-07-30 DOI: 10.1134/S0015462824605485

X. Zhou, S. Geng, L. T. Zhang

引用次数: 0

Mathematical Modelling of Targeted Delivery of Medicines to a Respiratory Tract 呼吸道药物靶向递送的数学模型

IF 0.6 4区工程技术

Fluid Dynamics Pub Date : 2025-07-30 DOI: 10.1134/S0015462824605461

D. V. Antonov, S. S. Sazhin, P. A. Strizhak, O. V. Nagatkina

引用次数: 0

Instability of the Flow in a Plane Channel with Compliant Walls of Finite Thickness 有限厚柔性壁平面通道内流动的不稳定性

IF 0.6 4区工程技术

Fluid Dynamics Pub Date : 2025-07-30 DOI: 10.1134/S0015462824605631

A. V. Boiko, E. S. Golub, A. P. Chupakhin

引用次数: 0

Anomalous Heat Transfer Enhancement in a Limited Package of Inclined Grooves on a Heated Section of a Plate in a Turbulent Air Flow 紊流中平板受热部分有限斜槽包内的异常换热增强

IF 0.6 4区工程技术

Fluid Dynamics Pub Date : 2025-07-30 DOI: 10.1134/S0015462824605540

S. A. Isaev, D. V. Nikushchenko, S. Z. Sapozhnikov, V. V. Mityakov, V. V. Seroshtanov, D. Kong, A. A. Klyus

{"title":"Anomalous Heat Transfer Enhancement in a Limited Package of Inclined Grooves on a Heated Section of a Plate in a Turbulent Air Flow","authors":"S. A. Isaev, D. V. Nikushchenko, S. Z. Sapozhnikov, V. V. Mityakov, V. V. Seroshtanov, D. Kong, A. A. Klyus","doi":"10.1134/S0015462824605540","DOIUrl":"10.1134/S0015462824605540","url":null,"abstract":"The abnormal intensification of a separated flow and heat transfer in limited packages of inclined grooves on a heated isothermal section of a plate in a uniform air flow at Re = 3 × 104 are numerically and physically modeled. The numerical predictions obtained on the basis of solutions of the Reynolds-averaged Navier–Stokes equations when closed by a model of shear stress transport and the energy equation are validated by comparing them with heat measurement data using the gradient heatmetry method of heat flux measurements in a package of four inclined grooves on a special thermophysical setup at St. Petersburg Polytechnic University (SPbPU). The influence of the number of grooves in limited packages on the intensification of the separated flow and heat transfer on a structured plate is analyzed on a previously created thermophysical setup for studying heat transfer in a single groove with the angle of inclination varying from 0° to 90°. It is shown that with an increase in the number of grooves, there is an increase in the relative heat transfer coefficients in them, caused by an increase in extraordinary pressure drops in the grooves as they move away from the leading edge of the plate, accompanied by an intensification of recirculating and swirling flows. A fundamental difference in the distribution of the relative heat transfer coefficient in the end part for the first and subsequent grooves in limited packages is established. As the number of grooves increases, heat transfer in the end sections intensifies.","PeriodicalId":560,"journal":{"name":"Fluid Dynamics","volume":"60 2","pages":""},"PeriodicalIF":0.6,"publicationDate":"2025-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145171722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0