Ian Zabel ME 547 – Transfer / Rate Process Weather Resistance and Bleed Air Control for the Diverterless Supersonic Inlet Ian Zabel ME 547 – Transfer / Rate Process

The Supersonic Inlet Diverter Function Redirect the boundary layer Ensure even pressure distribution Consequences Increase in inlet drag Complex structure and bleed system Significant radar reflection Types Ramp inlet bleed system (F-15, Tu-144) Formed Inlet Diverter (F-16) Combinations of Both

The Diverterless Supersonic Inlet (DSI) Function Divert the boundary layer through obstruction Prevent radar reflection and signal dispersion Benefits Low radar cross section (RCS) Structurally simple No critical need for bleed systems Downsides Potentially reduced pressure recovery Optimal within small speed ranges (transonic) Complicated design optimization (lots of testing) Poor / no weather resistance

Bleed Systems Function Purpose Mass flow rate control Cabin air quality (Passenger aircraft) Cooling of internal systems Shockwave Control Location After compressor – passenger aircraft Before compressor – Supersonic aircraft Damaged compressor blades/stators Current Problems Mechanically complex Bypass airflow wasted

Ice Buildup Cause and Prevention Occurrences High altitude, convective weather ~100 engine power loss events since 1990 Supercooled water and ice crystals Power Loss Ice entering compressor (no flow) Ice entering combustor (no fuel ignition) Damaged compressor blades/stators Current Mitigation Electrical heating – power draw and thin metal Vibration – mechanically complex if forced Avoiding the weather – restricted operation

Using Deicer Deicer Benefits Issues Alcohol, Salt, Glycols Used to modify the freezing point Similar to methods used on roads Benefits No system necessary on the aircraft No power draw on the aircraft Issues Requires airport resources Time intensive Unusable during flight

The ‘Weeping Wing’ Concept Porous Internal / External Surface Hole size increases along the diffuser Deicing chemical pumped through small holes Flows down internal surface into large holes Benefits Prevention of ice formation Bleed system addition potential Downsides Deicing chemicals potentially on blades Limited use, activated by pilot / sensors Potential boundary layer separation

System Combination Perforated Internal Surface Acts as bleed system Mechanically simple Shock location control Moisture and Ice Control Less surface area for ice crystals Potential for using condenser For subsonic, active prevention needed For supersonic, no concern due to shock Used in combination with ‘weeping wing’ Expose salt or alcohols to ice to remove

Conclusion Questions? Combined System Implications Final Result DSI doesn’t need significant bleed system, but… Slight mass flow rate control improves efficiency Ice control where and when needed Implications Broadened operational scope Reduced cold weather maintenance Increased aircraft capability Minimal change in RCS Final Result Significantly improved cold weather resistance Questions?