Multi-port air-intake

Fig. 15.21 Ducted rocket with multi-port air-intake.

When the airflow induced from the atmosphere is introduced through the singleport intake, the mixture formed in the forward part of the ramburner is fuel-lean because all the air induced from the single-port air-intake is introduced into the forward part. Thus, an excess-air mixture (fuel-lean mixture) is formed, the temperature of which becomes too low to initiate self-ignition. However, when a multi-port intake is used, the airflow is divided into two separate flows, entering at the forward part and the rear part of the ramburner. At the upstream flow, the air-to-fuel ratio can be made stoichiometric, which allows the mixture to ignite. At the downstream flow, the excess air is mixed with the combustion products and the temperature is lowered to increase the specific impulse. 

Fig. 15.23 Effect of air mixing process in the ramburner on combustion efficiency for two single-port intakes or two multi-port intakes as a function of boron particle size.

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