Aerodynamic Layout Designs Using of Microflaps for Flow Control of a Supersonic Finned Projectile

Xiaopeng Li,Tianming Wang,Yangzheng Zhao,Shun Kang

doi:10.1051/jnwpu/20193720344

Abstract

In this paper, the flow control system consists of some small microflaps located between the rear fins of the projectile. These microflaps can alter the flow field in the finned region of the projectile resulting in asymmetric pressure distribution and thus producing control forces and moments, furthermore to provide directional control for a supersonic projectile. Due to the small size and high speed characteristics of projectile, which is with fast and valid response characteristics, this flow control system has initially shown excellent potential in terms of supersonic flow control. The CFD simulation used here solves steady-state Reynolds-averaged Navier-Stokes equation with two-equation turbulence model k-ε. Firstly, we investigate the flow mechanism around microflap in supersonic flow, the flow fields around the microflap are complex, involving three-dimensional shock-shock, shock-boundary layer interactions. Secondly, for the microflap and the fin of Basic Finner configuration, the influence of microflap geometric parameters, microflap locations on aerodynamics is obtained and the interference mechanism is explored. Finally, several typical roll and pitch control layouts are described. According to the simulation results and their analysis, some preliminary conclusions can be drawn: by analyzing the flow interference mechanism between microflap and the fin, we find that the separated shocks ahead of the microflap, the bow shocks around microflap, and the trailing-edge wake, have influences on fin's surface pressure; among these factors, the bow shocks are stronger than separated shocks, furthermore it can generate larger high pressure region. Then we find out the aerodynamic characteristics of several typical control layouts at a supersonic speed, Ma=2.5, furthermore, hence nearly 4.8% drag is increase compared with the condition without microflap. As the number of microflaps increasing, the control aerodynamic forces and moments increases almost linearly. With a proper layout of the microflap's location, quick change in the surface pressure distribution can be achieved for rear fins of the projectile, the microflap should be mounted that can increase the high pressure zone, meanwhile, reduce the low pressure zone on the surface of fins, thus modulating the projectile's attitude can be realized.

Highlights

Dykes 等[9] 研究了采用突起物对弹箭方向控制的可行性方案,针对 Army⁃Navy 的超声速弹箭,详尽地研究了弹翼、突起物之间的干扰特性,分析了采用突起物进行偏航与滚转控制的可行性方案,给出了这些控制方案下气动力与力矩的变化规律。 Scheuermann 等[10] 针对 Basic⁃Finner 炮弹,在炮弹尾部翼面之间布置突起物,通过 CFD 数值计算与风洞试验,研究了突起物对弹箭的气动力与力矩特性影响规律。 Sahu 等[11] 针对 Basic⁃Finner 弹箭×形布局俯仰控制方案,在弹体尾部两片弹翼之间排布了 4 个突起物,详细地研究了不同马赫数与攻角下,突起物对全弹气动特性的影响规律,在亚声速与跨声速的状态下,突起物的排布对弹箭的气动特性影响较弱,在超声速的状态下,突起物产生的波系对弹翼的干扰较强,故引起弹箭气动特性变化较大。然而,目前较少有关于突起物与弹翼之间的干扰流场结构以及突起物相对于弹身的安装位置对弹翼气动特性影响规律的研究。
In this paper, the flow control system consists of some small microflaps located between the rear fins of the projectile
These microflaps can alter the flow field in the finned region of the projectile resulting in asymmetric pressure distribution and producing control forces and moments, to provide directional control for a supersonic projectile

Summary

Introduction

Dykes 等[9] 研究了采用突起物对弹箭方向控制的可行性方案,针对 Army⁃Navy 的超声速弹箭,详尽地研究了弹翼、突起物之间的干扰特性,分析了采用突起物进行偏航与滚转控制的可行性方案,给出了这些控制方案下气动力与力矩的变化规律。 Scheuermann 等[10] 针对 Basic⁃Finner 炮弹,在炮弹尾部翼面之间布置突起物,通过 CFD 数值计算与风洞试验,研究了突起物对弹箭的气动力与力矩特性影响规律。 Sahu 等[11] 针对 Basic⁃Finner 弹箭×形布局俯仰控制方案,在弹体尾部两片弹翼之间排布了 4 个突起物,详细地研究了不同马赫数与攻角下,突起物对全弹气动特性的影响规律,在亚声速与跨声速的状态下,突起物的排布对弹箭的气动特性影响较弱,在超声速的状态下,突起物产生的波系对弹翼的干扰较强,故引起弹箭气动特性变化较大。然而,目前较少有关于突起物与弹翼之间的干扰流场结构以及突起物相对于弹身的安装位置对弹翼气动特性影响规律的研究。图 5 为弹箭滚转控制方案 6(排布 4 个突起物) ,4 个突起物分别位于对角 2 个象限内,每个象限里排布 2 个突起物,2 个突起物距离弹翼前缘的距离分别为 8 mm,16 mm,突起物与就近弹翼的夹角为 15°,30°。表 7 为不同安装位置的突起物对气动特性的影响规律,相对于距离弹翼 3 mm 的突起物,另外 2 个构型的阻力分别减小 0.12 N,0.17 N;侧向力的绝对值增加量分别为 0.35 N,0.43 N,侧向力绝对值略有增加,增加量也较为平缓,这是由于图 16 中压力分布改变所致,高压区面积逐渐增加,低压区面积逐渐缩小所致。突起物自身产生的阻力分别减小 0.

Results

Conclusion