The CFD modelling of the ramjet start with low losses of the stagnation pressure was carried out. The basic feature of this start technology was the jet of compressed air creating effect of a throttle which aids in preliminary decelerating of the flow up to transonic velocities. The comparison with experiment was performed for the hydrogen burning. We studied the axial and near-wall supply of gas fuel. The physical mechanisms stimulating stable presence of transonic mode in the part with constant section were investigated within the frameworks URANS approach. It was shown that fuel supply blockage is a way to control near-wall supplying of gaseous fuel at considerably low pressure falls. And blocking the ignition processes is a way to control the axial supply at quite high pressure falls.

Numerical simulation of ignition of the gas mixture not mixed previously in the supersonic flow localized in a channel was performed. The ignition is initiated by the shock wave from the throttling jet, which results in significant changing of pressure difference between the main flow and the gas generator of the throttling jet. It is shown that applying boundary conditions similar to the breakdown of arbitrary discontinuity conditions, makes it possible to obtain the transonic mode observed in the experiment. The near-wall and axisymmetric supply of the gaseous fuel was considered.

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