Weather Resistance and Bleed Air Control for the Diverterless Supersonic Inlet IAN ZABEL ME 547 –...
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Transcript of Weather Resistance and Bleed Air Control for the Diverterless Supersonic Inlet IAN ZABEL ME 547 –...
Weather Resistance and Bleed Air Control for the Diverterless Supersonic InletIAN 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
◦ 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 Combined System
◦ 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?