Combustion Characteristics of a Solid Fuel Ramjet with Secondary Air Intake in Combustion Chamber

doi:10.12382/bgxb.2023.0905

Abstract

Abstract:

In response to the low combustion rate and efficiency caused by diffusion combustion in solid fuel ramjet, a solution involving a solid fuel ramjet withdual-side secondary air intake is proposed to improve combustion performance. A combustion model for the ramjet is established based on Standard k-ε turbulence model and vortex dissipation equations. Simulation calculations are conducted to analyze the internal flow field, burning surface recession rate, and combustion efficiency for both the basic ramjet model (without side air intakes) and the dual-side secondary air intake ramjet model. And the influence of bypass ratio on the performance of dual-side secondary air intake ramjet is investigated. The results indicate that the internal flow field of dual-side secondary air intake ramjet exhibits new flow field characteristics such as secondary recirculation zone and swirling zone, which contribute to enhanced mixing and combustion. Combustion efficiency and specific impulse (I_sp) increase first and then decrease with the increase in bypass ratio, reaching their highest values when the bypass ratio achieves 60%. Compared to the basic ramjet model, the combustion efficiency of dual-side secondary air intake ramjet is increased by nearly 40%, and its specific impulse is increased by 12.09% at a bypass ratio of 60%. Overall, the thrust increases with the increase in bypass ratio, with the maximum thrust being observed at a bypass ratio of 60%. However, the thrust increment diminishes gradually as the bypass ratio continues to increase.

Key words: solid fuel ramjet, secondary air intake, recession rate, combustion efficiency, thrust, specific impulse

CLC Number:

V235.21

CHANG Ya, WU Zhiwen, WANG Rui, GAO Kunpeng, ZHANG Zhe, WANG Ningfei. Combustion Characteristics of a Solid Fuel Ramjet with Secondary Air Intake in Combustion Chamber[J]. Acta Armamentarii, 2024, 45(12): 4451-4461.

Figures/Tables 17

Table 1 Comparison of experimental and numerical results

工况	入口内径/mm	装药长度/mm	空气流量/(kg·s^-1)	空气总温/K	压强/MPa	燃速/(mm·s^-1)
工况	入口内径/mm	装药长度/mm	空气流量/(kg·s^-1)	空气总温/K	压强/MPa	试验值	计算值
1	23.4	202	0.293	624	0.807	0.574	0.576
2	23.4	202	0.308	615	0.848	0.597	0.598

Fig.1 Physical Model

Table 2 Boundary conditions for flow field calculation

SFRJ模型	质量流量/(kg·s^-1)		总温/K
SFRJ模型	主路	旁路	总温/K
SFRJ基本模型	1		692
燃烧室双旁侧二次进气SFRJ模型	0.7	0.15	692

Fig.2 Grid Model

Fig.3 Grid independence verification

Fig.4 Analytical section of flow field

Fig.5 Temperature contour

Fig.6 Temperature distribution along the axial section

Fig.7 Pressure Contour

Fig.8 Upstream streamline distribution of combustion chamber

Fig.9 Downstream streamline distribution in combustion chamber

Fig.10 Streamline distribution in afterburning chamber

Fig.11 Analysis characteristic line of burning rate

Fig.12 Burning rates at different bypass ratios

Table 3 Variation of average burning rate

旁路比/%	平均燃速/(mm·s^-1)	增长率/%
0	0.784
10	0.830	5.97
20	0.842	1.46
30	0.855	1.48
40	0.859	0.46
50	0.826	-3.82
60	1.038	25.62
70	1.189	14.60
80	1.390	16.87
90	1.703	22.57

Fig.13 Combustion efficiencies at different bypass ratios

Fig.14 Thrust and specific impulse curves at different bypass ratios

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