| Popis: |
In the current work we focused our research on the intake starting process which is crucial for proper performance of Supersonic Combustion Ramjet engines. To this date there is no generally valid method to accurately predict intake starting for a certain three-dimensional SCRamjet intake configuration. Therefore we conducted starting experiments at Mach 6 and 7 in a blow down wind tunnel on a three dimensional intake model, equipped with a movable cowl and therefore variable internal contraction. Our focus was on the influence of the cowl geometry, the free stream Mach number, the angle of attack and the ratio of total temperature in the free stream to model wall temperature on intake starting. While the influence of total temperature was minor in the temperature ranges considered, the effect of angle of attack was twofold: when the intake was pitched, that the leading edge shock decreased in strength, the intake showed improved starting characteristics. For a pitch angle in the opposite direction and for increasing yaw angles, intake starting was prevented. For a decrease in free stream Mach number from 7 to 6, the starting internal contraction ratio was delayed from 1.92 to 1.73, for the v-shaped lip configuration. Exchanging the v-shaped lip with a straight lip geometry, improved intake starting and at a constant free stream Mach number of 7, the maximum internal contraction for starting moved from 1.92 to 2.12. |
