Propulsive Efficiency of Ridge/Inlet Configuration

Abstract

Controlling and directing the boundary layer on the surfaces of a flight vehicle are two of the most demanding challenges in advanced aerodynamic designs. The design of highly integrated and submerged inlets with a large offset between the entrance and compressor face is particularly challenging because of the need for controlling or reducing the adverse effects of the boundary layer on propulsive efficiency. S-duct diffusers are used widely in flight vehicles when the compressor face needs to be hidden, and their performance is generally sensitive to the quality of ingested boundary layer from the fuselage. Passive or active flow control mechanisms are needed to prevent flow separations at the bends. In this paper, a new method is presented for optimal inlet/body integration based on a pair of ridges ahead of the inlet and its effects on the performance of a semicircular S-duct inlet integrated on a flat surface using CFD. In this design, the ridge changes an inefficient inlet concept to one with acceptable performance. The new method of integration is practicable for top-mounted inlet configurations where the use of diverters and other mechanisms results in higher amounts of drag, weight, and complexity.

Aerodynamic efficiency analysis of the ridge integrated submerged inlet

“…The possibility of using a ridge configuration as a passive boundary layer diverter for submerged inlet was investigated recently. 18,19 entrance by transferring it to a pair of streamwise vortices along a predefined path as shown in Figure 2(b). Controlling the vortex breakdown at the end of the ridge is the most important challenge in using the concept; it creates an expanding chaotic pattern which can be ingested by the inlet.…”

“…The possibility of using a ridge configuration as a passive boundary layer diverter for submerged inlet was investigated recently. 18,19 Figure 2(a) shows the baseline boundary layer diverter and its vortex. The ridge diverts the upstream boundary layer before the entrance by transferring it to a pair of streamwise vortices along a predefined path as shown in Figure 2(b).…”

“…(a) Baseline ridge and the captured vortex pattern on a cross-section in 2018, Re = 2.7956e+5. 18 (b) Boundary layer diversion by the ridge vortices 19 (c) Vortex core filaments M ∞ = 0.5, Re = 2.3067e+7. 19 …”