| Popis: |
A streamline-traced Busemann inlet was tested in the Virginia Tech supersonic blowdown wind tunnel in a Mach 4.08 freestream flow. These tests involved the starting and operational characteristics of a high contraction ratio (10) circular inlet, commonly referred to as a ‘sugar scoop’. For this inlet, Mach 4.08 is near the limit of isentropic-compression and beyond some empirically derived viscous operational limits. In addition, at this speed the internal contraction ratio of the scoop design is significantly above the Kantrowitz criterion for starting. In order to operate the inlet supersonically at Mach 4.08, the inlet must spill at least enough air to reduce the effective contraction ratio below these limits. To achieve starting and allow supersonic operation of the inlet at low speeds, a sliding door was integrated into the region of the inlet crotch to reduce the internal contraction of the inlet and allow additional spillage. Both unsteady 3D viscous CFD and an experimental investigation were performed. In the experiment, starting and operation were verified with the door near the full open position. The mass flow rate of the captured air was measured and aerothermodynamic probing of the flow downstream of the inlet throat was accomplished. Results verified that the flow had become supersonic at the inlet throat when the door was opened slightly over two-thirds of its full travel. The experimental trends qualitatively agreed with the CFD simulations. |
