Fundamental Challenges of Micro-Vanes and Micro-Ramps for High-Speed Inlet Applications: A Computational Fluid Dynamics Investigation

Abstract

Computational Fluid Dynamics simulations were conducted on traditional, subboundary layer micro-vane and micro-ramp flow control devices under simulated Mach 2 and 2.5 supersonic conditions. A CFD based numerical investigation was undertaken to assess and characterize the fundamental strengths and weaknesses associated with passive sub-boundary layer micro-vanes and micro-ramps in a supersonic flowfield. The purpose of the computatio nal investigation was to identify fundamental limitations of sub-boundary layer micro-vanes and micro-ramps with the intention to (later) develop advanced shaped mi cro-devices that can overcome or minimize any identified limitations. A brief comput ational excursion was also conducted to assess the performance impact of locating sub-boundary layer microvanes and micro-ramps on a porous surface (similar to a traditional inlet bleed system) where the diameter of the holes characteriz ing the porous surface approached the characteristic height of the micro-d evice. The observations resulting from this computational study concluded sub-boundary layer micro-vanes primarily suffer from vortex lift-off in addition t o associated inlet integration issues such as the threat of thermal erosion in high tempe rature environments or introducing a FOD hazard due to structural failure. Sub-boundary layer microramps tended to immediately displace the created vo rtex pair away from the nearwall region before a significant amount of high momentum, high energy fluid was transferred to the targeted deficient region of the boundary layer. Sub-boundary layer micro-vanes consistently outperformed sub-boundary layer micro-ramps of equivalent height when utilizing two differing comp arative metrics. Directly locating either sub-boundary layer micro-vanes or micro-ramps on a porous surface resulted in a significant degradation in the micro- devices’ performance, relative to a solid surface, when the diameter of the holes appro ached the characteristic height of the micro-device.