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MAE 4261: AIR-BREATHING ENGINES. Overview of Axial Compressors Mechanical and Aerospace Engineering Department Florida Institute of Technology D. R. Kirk. Radial (Centrifugal) Devices Can not handle as high mass flow Less efficient than axial device Short length Robust Less Parts.
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MAE 4261: AIR-BREATHING ENGINES Overview of Axial Compressors Mechanical and Aerospace Engineering Department Florida Institute of Technology D. R. Kirk
Radial (Centrifugal) Devices Can not handle as high mass flow Less efficient than axial device Short length Robust Less Parts Axial Devices High mass flow High efficiency Stackable (multi-staging) More parts More complex TWO PRIMARY TYPES OF COMPRESSORS
WHERE IN THE ENGINE? PW2000 Fan Compressor
2 SPOOL DEVICE: PW2000 Low Pressure Compressor (wlow) High Pressure Compressor (whigh) High and Low Pressure Turbines
SCHEMATIC REPRESENTATION Single Shaft Compressor Twin-Spool Turbofan
2 SPOOL DEVICE Low Pressure Spool Low Pressure Compressor High Pressure Compressor
FEATURES OF INTEREST: PW2000 Intra-Blade Supports Change in cross sectional flow area Disks (centrifugal stress) also called ‘Blisks’ Blades are twisted
AXIAL COMPRESSOR: SCHEMATIC REPRESENTATION Centerline Centerline
REVIEW: PRESSURE DISTRIBUTION • Rotor • Adds swirl to flow • Adds kinetic energy to flow with ½rv2 • Increases total energy carried in flow by increasing angular momentum • Stator • Removes swirl from flow • Not a moving blade → cannot add any net energy to flow • Converts kinetic energy associated with swirl to internal energy by raising static pressure of flow • NGV adds no energy. Adds swirl in direction of rotor motion to lower Mach number of flow relative to rotor blades (improves aerodynamics)
AXIAL COMPRESSOR ENERGY EXCHANGE • Rotor • Adds swirl to flow • Adds kinetic energy to flow with ½rv2 • Increases total energy carried in flow by increasing angular momentum • Stator • Removes swirl from flow • Not a moving blade → cannot add any net energy to flow • Converts kinetic energy associated with swirl to internal energy by raising static pressure of flow • NGV adds no energy. Adds swirl in direction of rotor motion to lower Mach number of flow relative to rotor blades (improves aerodynamics) w Centerline S R R NGV
LOSSES AND CASCADE TESTING Measure of loss correlated to Blade geometry and Easily measured in cascade
ENGINE TESTING: BIRD STRIKE http://100.rolls-royce.com/facts/view.jsp?id=215
ADDITIONAL ISSUES AND BLADE TESTING • Other Issues • High Cycle Fatigue • Materials • Manufacturing • Containment of Blade • Disk Rupture • Sealing • Tip and Hub Losses • Turbine Cooling Bleed • Inspection • Replacement Parts ($) ‘Blade-Out’ Simulation