Influence of geometrical and thermal actions on the flow characteristics in the ramjet channel

The comparative analysis is carried out to determine the effect of the increased pressure resulting from the thermal or geometrical action on the flow characteristics (pressure, total pressure reduction, Mach number) on the base of the results of numerical investigation of the transition from the supersonic to subsonic flow in the diffusor (opening angles Θ = 10° and 90°) of the supersonic air inlet in the ramjet. Analysis of calculation results enables to find the relation between the heat addition and geometrical action on the flow in the channel, when the total pressure reductions feasibly coincide in the diffusor. In this case, the static pressure and Mach number at the combustion chamber entrance are also close to each other. It is shown that, when the diffusor with big opening angles is used for the above mentioned actions, the total pressure may rise by 2.7 ÷ 3 in the combustion chamber, which does not influence the air inlet performance and hence the automatic controllability of the total pressure ahead the combustion chamber entrance is provided.