Experimental Investigation of the Starting Behavior of a Three-Dimensional Scramjet Intake

Abstract

To this date, there is no generally valid method to accurately predict intake starting for a certain three-dimensional scramjet intake configuration. Therefore, experiments are conducted at Mach 6 and 7 in a blowdown wind tunnel on a three-dimensional intake model, equipped with a movable cowl and therefore variable internal contraction. The internal contraction is slowly decreased, and the performance parameters at the interface to the combustion chamber are measured with a rake. The general trends from the Kantrowitz diagram were able to be reproduced, namely enhanced intake starting for higher freestream Mach numbers and lower internal contraction ratios. Furthermore, the effect of the angle of attack was twofold: When the intake was pitched, the leading-edge shock decreased in strength, and the intake showed improved starting characteristics. For increasing yaw angles, intake starting was hindered. Exchanging the -shaped cowl with a straight-cowl geometry improved intake starting due to the additional mass spillage. Once the intake was started, increasing the internal contraction ratio to 2.56 did not cause the intake to unstart for all Mach numbers investigated.