Irreversibilities in Propulsion Systems P M V Subbarao

Irreversibilities in Propulsion Systems P M V Subbarao Professor Mechanical Engineering Department A Major Criteria for Geometric Design of Components…. .

Irreversible Turbofan Cycle : Unwanted Entropy Generation Inlet 4 1 2 3 7 c 5 6 7 h

Irreversible Turbofan Cycle : Unwanted Pressure Loss Inlet 4 1 2 3 7 c 5 6 7 h

Ideal & Irreversible Turbofan cycle

Irreversible Propulsion cycle

Classification of Irreversibilities • Internal Irreversibilities : Friction, flow separation & Turbulence • External Irreversibilities: Shocks, Friction, flow separation & Turbulence • Heat loss & incomplete combustion

External Irreversibilities due to Intake System

Typical External flow at Subsonic Cruising Conditions

Geometry of Subsonic Inlet at the Entrance

External Flow Irreversibilities in Subsonic Intakes Supercritical. Design

Control of Additional Drag in Intake Systems

Normal Shock Intakes A sharp lipped subsonic diffuser may be used in supersonic engine without a significant aerodynamic penalty for Mac < 1. 6.

Modes of Operation of External Compression Inlets

Performance of Subsonic Diffuser with NS PRF

Selection of Subsonic Diffuser with NS The total pressure recovery of a normal shock rapidly deteriorates beyond Mach ~ 1. 6. 90% total pressure recovery is achieved at 1. 6.

External Compression Inlets M>1 Oblique Shock Normal Shock Cowl Shock A single compression ram inlet involves one oblique shock and one normal shock.

Performance of External Compression Inlets PRF

Modes of Operation of External Compression Inlets

Location of Oblique shock & External Drag No Slippage but High External drag Slippage with low External drag

Variable Geometry Inlets.

A High Quality Interior Geometry