Drag Reduction by Boundary-Layer Combustion: Effects of Flow Disturbances from Rectangular-to-Elliptical-Shape-Transition Inlets

作者：Chan Wilson Y K^*; Mee David J; Smart Michael K; Turner James C

来源：Journal of Propulsion and Power, 2015, 31(5): 1256-1267.

DOI：10.2514/1.B35335

A key issue that can affect the implementation of boundary-layer combustion for viscous drag reduction in scramjet combustors is the potential of nonuniform flow entering the combustor from the inlet. Experiments were conducted in the T4 Stalker tube to study the effects of these flow nonuniformities on boundary-layer combustion in a circular constant-area combustor. A rectangular-to-elliptical shape-transition inlet, typical of the type proposed for self-starting scramjets, was designed, manufactured, and attached upstream of the combustor in the current experiments. Numerical simulations of the flow through the rectangular-to-elliptical shape-transition inlet showed that the inlet generated a nonuniform outflow that had vortices, shock waves, and expansion waves. When tested at design-point inflow conditions, the total skin friction drag measured in the combustor was reduced by 61% when hydrogen burned in the boundary layer. These levels of reduction are similar to those measured in experiments conducted without a realistic scramjet inlet upstream of the combustor, thus demonstrating that the drag reduction brought about by boundary-layer combustion is not affected by the flow disturbances generated from the REST inlet. Tests conducted at off-design conditions further demonstrated that the drag reduction brought about by boundary-layer combustion was not affected by changes in the inflow conditions.

• 出版日期2015-10