The gas flow inside an ejector under pulse periodic impact of a detonation wave is investigated numerically. The flow behind the detonation wave that exits a long detonation tube 20 mm in diameter is used as the ejecting gas. The initial distributions of the gas velocity, the pressure, the temperature, and the density are preset inside the detonation tube. The Navier-Stokes equations are solved using the second order Roe type finite difference scheme. The flow rate of the ejected air and the thrust generated by the jet engine under pulsating conditions are determined. It is shown that the use of an ejector can yield thrust augmentation by 17%.
The investigation considered a spherical flame front propagating in free space filled with a hydrogen-air mixture containing 15 % hydrogen. The experiments were conducted inside latex shells. We initiated combustion in the centre of the volume, using either a 1 mJ spark or a nichrome wire explosion releasing 5 J of energy. In the case of the 7 m3 and larger shells, we recorded video data on the flame front using an InfraTec ImageIR 8320 infrared camera featuring a 2.0--5.7 μm spectral ranges and a rate of 300 frames per second. In the case of the 0.003 m3 and smaller shells, we visualised the processes by means of an IAB-451 schlieren system. We recorded these images using a Videosprint G/2 visible-wavelength camera at a rate of 1000 frames per second. We identified the differences in flame front acceleration dynamics for the same combustible mixture composition and flame initiation energy. We found that the distribution function specifics concerning the pre-exponential factors in the power law of flame front acceleration indicate that individual random perturbations have a considerable effect at the initial stage of quasi-spherical flame front formation. We compared flame front propagation for the cases when the initiation energy was 1 mJ and 5 J respectively and determined that the initiation energy also affects the process
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