1. 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

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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?