An improvement of the base bleed unit on base drag reduction and heat energy addition as well as mass addition

Xue, Xiaochun; Yu, Yonggang

doi:10.1016/j.applthermaleng.2016.08.072

Cited by 13 publications

(10 citation statements)

References 18 publications

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“…The test shows that under the conditions of artillery firing, the base-bleed propellant is at a critical state of re-ignition after permanent extinguishment and extinguishment. Xue [4] et al simulated the gas combustion and flow process of the supersonic wake of base-bleed projectile to analyze the key factor of drag reduction and pressure decrease of base bleed projectile.…”

Section: Numerical Simulation and Unsteady Combustion Model Of Ap/htpmentioning

confidence: 99%

Numerical Simulation and Unsteady Combustion Model of AP/HTPB Propellant under Depressurization by Rotation

2019

Propellants Explo Pyrotec

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In order to study micro‐scale combustion characteristics of base‐bleed propellant ammonium perchlorate/hydroxyl terminated polybutadiene (AP/HTPB) under rotation condition, a two‐dimensional unsteady rotating combustion model of periodic sandwich model of AP/HTPB was established. In the gas phase, a two‐step overall reaction was used to couple the gas‐solid boundary layer, the rotational momentum was fitted and the numerical simulation comparative analysis under the initial combustion pressure of 0.1 MPa–5 MPa and the rotation velocity of 0–10 800 r min−1 was experimented. The results show that under the conditions of an initial combustion pressure of 3.5 MPa, a depressurization rate of 1000 MPa s−1 and a rotation velocity of 10 200 r min−1, the formation of a narrow diffusion‐controlled chemical reaction zone appears in the initial stage of depressurization. When the combustion pressure drops to about 0.88 MPa, the flame shows dual characteristics: diffusion‐controlled and premixed combustion. When the pressure dropped to 0.1 MPa, the flame is premixed combustion. The steady combustion process at different combustion pressures and different rotational velocities was analyzed numerically. The results show that there is a linear positive correlation between the flame deflection angle and the pressure. When the rotation velocity is lower than 10 000 r min−1, the deflection angle of the gas flame increases linearly with the rotation velocity. However, when the rotation velocity is higher than 10 000 r min−1, the deflection angle and the rotation velocity of the gas flame increase exponentially. The trend of the average Reynolds number of the combustion surface is basically the same as that of the deflection angle of the gas flame. Therefore, the average Reynolds number of the combustion surface can be used to describe the influence of rotation and pressure on the deflection angle of the gas phase flame.

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Section: Numerical Simulation and Unsteady Combustion Model Of Ap/htpmentioning

confidence: 99%

Numerical Simulation and Unsteady Combustion Model of AP/HTPB Propellant under Depressurization by Rotation

2019

Propellants Explo Pyrotec

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“…At low injection rates, the base pressure rise is nearly proportional to the enthalpy of the bleed gas. The peak base pressure is higher, and occurs at a lower of the bleed mass-flow rate, than for the corresponding cold bleed case [6,9]. Therefore, present study is focused on base drag optimization of a 122 mm artillery projectiles using a BB technology.…”

Section: Introductionmentioning

confidence: 99%

“…Such a capability is of significant current interest. Detailed understanding of the energy as well as mass addition and the fluid-dynamic interactions occurring around the projectile and especially the afterbody flow is a requirement before proposing solutions to reduce the drag [5,6]. In actual system, the mass-flow rate injected in the afterbody flow is provided by the combustion of the propellant.…”

Section: Introductionmentioning

confidence: 99%

“…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].…”

Section: Introductionmentioning

confidence: 99%

“…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]. At low injection rates, the base pressure rise is nearly proportional to the enthalpy of the bleed gas.…”

Section: Introductionmentioning

confidence: 99%

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Optimization of artillery projectiles base drag reduction using hot base flow

Amin

Jaramaz

2019

Therm sci

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The CFD numerical simulations were carried out to investigate the base drag characteristics of a projectile with base bleed unit with a central jet. Different base bleed grain types with different combustion temperatures were used. The goal was to find a way to effectively control the base flow for base drag reduction and optimisate the latter using an adequate CFD software. Axisymmetric, compressible, mass-averaged Navier-Stokes equations are solved using the k-ω SST, transition k-kl-ω, and RSM turbulence models. The various base flow characteristics are obtained by the change in the non-dimensionalized injection impulse. The results obtained through the present study show that there is an optimum bleed condition for all base bleed grains tested. That optimum is dependent on the temperature of the grain combustion products. The optimum reduces the total drag for 6,9% in the case of air injection at temperature of 300 K and reaches up to 28% in the case of propellant combustion products injection at almost 2500 K. Besides, the increasing of molecular weight has a role no less important than temperature of the combustion products in terms of base drag reduction.

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Investigation of thermal performance in dual‐fuel units

Xue

2022

Energy Science & Engineering

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Numerical studies were carried out to investigate the thermal performance of the muzzle flow with strong shock discontinuities and gas-gas heat transfer mechanism in the base bleed unit (BBU) of an aerodynamic vehicle under the combined effects of muzzle flow and depressurization process. The process was modeled using the Navier-Stokes equations with chemical kinetics and interior ballistic equations. The results show that the muzzle phenomena with large temperature gradients and different wave structures appear after the supersonic vehicle enters into the free-flight stage. The BBU also experiences a strong depressurization process with the release of high-temperature propellant gas at 2200 K. However, the igniter combustion gas at a higher temperature of 3050 K in the BBU develops downstream and upstream repeatedly under the combined effects of the base wave and depressurization process, which makes the energy conversion process in the unit more complicated. With the projectile leaving the control of the muzzle flow, the BBU is full of the igniter combustion gas and the energy in the unit is uniformly distributed gradually. The high-temperature area, at approximately 2750 K, propagates downstream along the axial and radial directions simultaneously until it finally dominates the entire unit. The maximum temperature of the combustion gas acting on the propellant surface is always 2740 K and the maximum heat flux remains approximately 1250 W/cm 2 at later periods.

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An improvement of the base bleed unit on base drag reduction and heat energy addition as well as mass addition

Cited by 13 publications

References 18 publications

Numerical Simulation and Unsteady Combustion Model of AP/HTPB Propellant under Depressurization by Rotation

Numerical Simulation and Unsteady Combustion Model of AP/HTPB Propellant under Depressurization by Rotation

Optimization of artillery projectiles base drag reduction using hot base flow

Investigation of thermal performance in dual‐fuel units

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