Numerical And Experimental Research On The Ramjet Combustor Based On Cavity

Ramjet combustor with cavity as flameholder has simple configuration and excellent flamehold characteristic. Experimental and numerical investigation, which focused on the technique of flamehold and high combustion efficiency, were conducted based on an axisymmetric ramjet combustor.Firstly, the ignition characteristic in an axisymmetric ramjet model combustor with cavity as flameholder was experimentally conducted. The size of cavity and mechanism of flame spread in circumference and axial direction were analysised through ignition experiments of various cavity layout and different constitution. Results revealed that the stored-up energy by the cavity is determined by the size of cavity, which is necessary for the flame spread before the establishment of combustion. The way the kerosene injected into the combustor is also a vital factor, which affects the reliability of ignition. Then the method of combustion performance evaluation was summarized and experiments were carried to examine the effects of the cavity parameter on the combustion performance. Several ignition tests under low pressure, which give an elemental knowledge about difficulties of ignition under low pressure, were implementedThe flow field of connected-pipe combustor at ground pressure was studied numerically. It can be concluded that different flow filed before ignition, which depended on various factors, lead to distinct concentration of kerosene which affect the ignition characteristic. The combustion field of H2 should be organized properly when using H2-induced ignition. The work model of cavity differ according to the temperature in cavity, in which the degree was determined by the method and efficiency of injection and distance before cavity. The inflammation, which was difficult to expand to the main flow and was limited within a narrow area, extended only to the surround of the wall where combustion occurred.Two solutions to flame spread problem were proposaled in the purpose of overcome the ignition difficulty of work at low pressure,which were analysied preliminaryly with numerical simulation.