Abstract: This invention relates to air breathing engines, such as ramjets, scramjets and internal combustion, and more particularly to an active combustion control device for a combustor. In more particularity, the present invention relates to a method and apparatus that applies active combustion control technology to advanced propulsion devices and closed-loop fuel injection at sub-harmonic frequencies of the instability frequency of the combustor. The problem of limited actuator frequency response is addressed by injecting fuel pulses at sub-harmonic frequencies of the instability. The fuel may be liquid, solid or gas. To achieve this desired result, a closed loop controller is designed to determine sub-harmonic frequencies using a divider to divide the instability frequency of a combustor, yielding a fraction of the harmonic frequency.

Abstract: This invention relates to air breathing engines, such as ramjets, scramjets and internal combustion, and more particularly to an active combustion control device for a combustor. In more particularity, the present invention relates to a method and apparatus that applies active combustion control technology to advanced propulsion devices and closed-loop fuel injection at sub-harmonic frequencies of the instability frequency of the combustor. The problem of limited actuator frequency response is addressed by injecting fuel pulses at sub-harmonic frequencies of the instability. The fuel may be liquid, solid or gas. To achieve this desired result, a closed loop controller is designed to determine sub-harmonic frequencies using a divider to divide the instability frequency of a combustor, yielding a fraction of the harmonic frequency.

Abstract: This invention relates to air breathing engines, such as ramjets, scramjets and internal combustion, and more particularly to an active combustion control device for a combustor. In more particularity, the present invention relates to a method and apparatus that applies active combustion control technology to advanced propulsion devices and closed-loop fuel injection at sub-harmonic frequencies of the instability frequency of the combustor. The problem of limited actuator frequency response is addressed by injecting fuel pulses at sub-harmonic frequencies of the instability. The fuel may be liquid, solid or gas. To achieve this desired result, a closed loop controller is designed to determine sub-harmonic frequencies using a divider to divide the instability frequency of a combustor, yielding a fraction of the harmonic frequency.

Abstract: This invention relates to air breathing engines, such as ramjets, scramjets and internal combustion, and more particularly to an active combustion control device for a combustor. In more particularity, the present invention relates to a method and apparatus that applies active combustion control technology to advanced propulsion devices and closed-loop fuel injection at sub-harmonic frequencies of the instability frequency of the combustor. The problem of limited actuator frequency response is addressed by injecting fuel pulses at sub-harmonic frequencies of the instability. The fuel may be liquid, solid or gas. To achieve this desired result, a closed loop controller is designed to determine sub-harmonic frequencies using a divider to divide the instability frequency of a combustor, yielding a fraction of the harmonic frequency.

Abstract: This invention relates to air breathing engines, such as ramjets, scramjets and internal combustion, and more particularly to an active combustion control device for a combustor. In more particularity, the present invention relates to a method and apparatus that applies active combustion control technology to advanced propulsion devices and closed-loop fuel injection at sub-harmonic frequencies of the instability frequency of the combustor. The problem of limited actuator frequency response is addressed by injecting fuel pulses at sub-harmonic frequencies of the instability. The fuel may be liquid, solid or gas. To achieve this desired result, a closed loop controller is designed to determine sub-harmonic frequencies using a divider to divide the instability frequency of a combustor, yielding a fraction of the harmonic frequency.

Abstract: A shear layer of a fluid flow has relatively large vortical structures generated by acoustic forcing from oscillations induced in a cavity closely adjacent to the flow so that these structures enhance mixing at the layer. The forcing frequency is selected by varying the dimensions of the cavity, and several cavities of different dimensions may be provided for forcing at different frequencies, including beat frequencies. The cavity provides passive, high amplitude forcing effective with a compressible shear layer due to high speed flow, including supersonic flow. Cavities of differing configuration provide forcing for fluid flow from nozzles of different geometries. The most effective enhancement is provided by particular excitation frequencies generated by a cavity having a size selected in accordance with dimensionless relations between the flow parameters and nozzle geometry.