Abstract:
In order to obtain the characteristics and structural regulation law of the RBCC (Rocket-Based Combined-Cycle) engine in a flight Mach number range of
Ma0 = 0~8, an engine characteristic analysis model is established based on experimental data, which adopts the control volume method and takes into account the effects of heat complete gas, chemical equilibrium flow, viscosity loss, heat loss, etc. The model is then verified using the thrust and specific impulse data obtained in a free-jet experiment. Characteristics of the RBCC engine of two-dimensional variable structures are analyzed for three operation modes, i.e. the injector operation mode, the ramjet operation mode and the rocket & ramjet mode. Effects of the flight dynamic pressure, Mach number, angle of attack, equivalent ratio and rocket flow rate on the performance of the model engine are quantitatively obtained. A characteristic analysis is carried out for the
Ma0 = 0~8 RBCC engine along a simulated trajectory, and variations with the flight Mach number at different engine operation modes are given for the air inlet contraction ratio, combustor expansion ratio, nozzle expansion ratio, total area ratio. The results show that: 1) Under the ejector operation mode, for every increasement of one in the flight Mach number, the engine thrust and specific impulse are increased by about 18.2%, and the rocket thrust gain is increased by about 15%. 2) Under the ramjet operation mode, with the increase of the rocket flow rate, the rocket thrust gain decreases, and the larger the rocket flow rate is, the narrower the positive rocket thrust gain range is. 3) During the operation mode transformation at
Ma0 = 2, the performance and structural parameters of the engine are both discontinoues, thus special attention needs to be put for the continuous adjustment of the thrust and structural parameters of the engine. 4) Under the given simulated trajectory, the inlet contraction ratio, the combustor expansion ratio, the nozzle expansion ratio and the engine total area ratio vary 6.17, 4.26, 30.38, 8.94 times in the range of
Ma0 = 0~8,respectively.