Numerical and experimental investigation of the effect of geometry on combustion characteristics of solid-fuel ramjet

International Journal of Aerospace Engineering

et al. 2021

Self Cite

In this work, 2D numerical RANS (Reynolds Average Navier-Stokes) simulations were carried out to investigate the thermodynamic performance of a solid fuel ramjet (SFRJ) with different inlet conditions. This is achieved by using an in-house FORTRAN code to simulate a 2D turbulent, reacting, unsteady flow in the ramjet engine. The inlet conditions are characterized by three key parameters: (1) swirl number ( S N ), (2) mass flow rate ( m ̇ air ), and (3) inlet temperature ( T in ). With the code numerically validated by benchmarking with a number of computed cases, it is applied to perform systematic studies on the turbulent flow recirculation, combustion, and heat transfer characteristics. It is found that increasing S N , m ̇ air , or T in can dramatically enhance the combustion heat release rate, regression rate, and combustor average temperature. Furthermore, the analysis on the chemical reaction intermediate (CO) reveals that the chemical reaction is more sufficient with increased m ̇ air , but S N = 0 . In addition, a secondary vortex is generated at the corner of the backward facing step in the presence of a swirl flow resulting from the instability of the shear layer. Finally, the nonlinear correlations between the heat transfer, combustion characteristics, and flow field characteristics and the corresponding inlet thermodynamic parameters are identified.

Section: Heat Transfer Characteristics Figure 11 Describes the Regres...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Inlet Thermodynamic Conditions on Solid Fuel Ramjet Performances

Zhao

International Journal of Aerospace Engineering

et al. 2021

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“…In Equation ( 13), the value of A py and E apy could be found in Reference [37], and the temperature of solid fuel surface could be represented by T ω .…”

Section: Chemical Reaction Modelmentioning

confidence: 99%

Numerical Investigation of the Effect of Sudden Expansion Ratio of Solid Fuel Ramjet Combustor with Swirling Turbulent Reacting Flow

Cai

et al. 2019

Energies

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In this paper, the effect of sudden expansion ratio of solid fuel ramjet (SFRJ) combustor is numerically investigated with swirl flow. A computational fluid dynamics (CFD) code is written in FORTRAN to simulate the combustion and flow patterns in the combustion chamber. The connected-pipe facility is used to perform the experiment with swirl, and high-density Polyethylene (HDPE) is used as the solid fuel. The investigation is performed with different sudden expansion ratios, in which the port and inlet diameters are independently varied. The results indicated that the self-sustained combustion of the SFRJ occurs around the reattachment point at first, and then the heat released in reattachment point is used to achieve the self-sustained combustion in the redevelopment zone. The average regression rate is proportional to the sudden expansion ratio for the cases with a fixed port diameter, which is mainly dominated by the enhancement of heat transfer in backward-facing step. However, the average regression rate is inversely proportional to the sudden expansion ratio for the cases with fixed inlet diameter, which is influenced by the heat transfer mechanism of developed turbulent flow in the redevelopment zone.

“…It was found that the local regression rate is closely related to the local convective heat flux, downstream conditions do not influence the regression pattern, and mean regression rate decreased with the increase of port diameter. Moreover, Gong et al [8,9] pointed out that the star solid fuel demonstrated higher space-averaged regression rate than that of the traditional single-port cylindrical solid fuel. They conducted an experimental and numerical investigation on the combustion characteristics of the SFRJ with star solid fuel.…”

Section: Introductionmentioning

confidence: 99%

Unsteady Simulation of Ignition of Turbulent Reactive Swirling Flow of Novel Design of Solid-Fuel Ramjet Motor

Musa

et al. 2019

Energies

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This paper presents a numerical investigation of ignition and combustion stabilization of a novel design of a solid-fuel ramjet (SFRJ) motor with and without swirl flow. The proposed design includes two solid fuels, retaining the simple design of the classic SFRJ. Numerical simulations of unsteady, turbulent, reactive, and swirling flow coupled with solid-fuel pyrolysis have been performed using an in-house CFD solver. Experiments on SFRJ were conducted via a connected-pipe test facility to validate the developed code. Furthermore, the code was validated for chemical reactions, heat diffusion, and swirl flow by using benchmark test cases of shock-induced, semi-infinite plate, and dump combustor with swirl flow, respectively. Then, the proposed and classic designs were simulated for the same inflow conditions and configurations, and the results were analyzed and discussed. It is found that the mixing degree, reactant residence time, mass flux, ignition delay time, and regression rate improve when using the proposed design. Moreover, the proposed design reveals interesting observations of a new flame being created and merged with the main flame.