Wind tunnel study of aerodynamic characteristics of base combustion

Abstract

This paper discusses experimental research on the aerodynamic characteristics of base bleeding with combustion of fuel-rich solid fuel in flows at subsonic, transonic, and supersonic speeds. The effects of ejection parameter, freestream Mach number, geometry parameter of jet hole, rotary speed of model, and combustion temperature at jet hole on the base drag reduction rate for the model are investigated. The results show significant differences of drag reduction characteristics between base combustion of fuel-rich solid fuel and base bleeding of cold or hot gas. Nomenclature C Db = base-drag coefficient without base combustion (or base-bleed) C Dbj = base-drag coefficient with base combustion (or base-bleed) &C Db = (C Db = base-drag reduction rate due to base -C Dbj )/C Db combustion (or base-bleed) D b = base diameter DJ = jet hole diameter / = m/pVS b = ejection parameter Mso = Mach number of freestream m = mass burning rate of fuel-rich solid fuel P b = base pressure of model P^ = static pressure of freestream R = mean linear burning rate with rotation -0 = mean linear burning rate with zero rotary speed S b = base area of model T b= combustion temperature at jet hole T 0 = total temperature of freestream t = combustion time V = velocity of freestream p = density of freestream -(dC Db /dI) I=0 = drag reduction efficiency of base combustion (or base bleed)

Effect of Base Bleed Dimensions on the Ballistic Performance of Artillery Projectiles

“…Figure 22 shows the change of projectile range at different exit diameters of base bleed unit and different maximum radii of base bleed grain while the grain length and inner diameter are constant. For each R max , the range increases with the increase in D exit up to a certain value then, no further increase occurs This agrees with the mentioned in [8,15] which stated that exit diameter has no considerable influence on base pressure when reaches certain size. The exit diameter increases with the increase of R max .…”

“…Ejected gases from the base bleed unit are responsible for the base drag reduction resulting in range extension of artillery projectiles. Base bleed effect has been studied by many researchers using different approaches such as firing tests [1][2][3][4][5], wind tunnel experiments [6][7][8][9], analytical methods [10][11][12][13][14][15][16][17] and computational fluid dynamic simulations [18][19][20][21]. In some of these studies, the researchers used solid propellants as the source of the ejected gases.…”

Optimization of artillery projectiles base drag reduction using hot base flow

“…Experiments performed by several researchers [6][7][8][9] to study the effect of bleed mass-flow rate on the base pressure exhibit certain common characteristics and indicate three distinct operating regimes based on the quantity of bleed fluid injected. The results of various studies using air, hydrogen, helium, argon and nitrogen have shown that afterbody flows with BB can result in base drag reduction [6][7][8][9]. The significant increases in base pressure have also been observed using a heated bleed gas [6,9].…”

Direct Numerical Simulations of Transitional Supersonic Base Flows

“…However, to modify the near-wake flow effectively, the fundamental physical mechanisms that govern the development and evolution of coherent structures in the wake, leading to an alteration of the base pressure, need to be understood. Only then can efficient modifications of the near wake be implemented in the form of passive control such as base bleed, 2−9 boattailing, 10−12 base burning, 13,14 etc., or, eventually, even active flow control.…”