07-08-2012, 09:49 AM
Jet Propulsion and Compressor Design
Compressor Design.ppt (Size: 2.75 MB / Downloads: 196)
Fluid Machinery
Positive Displacement
Working fluid is confined within a boundary.
Energy transfer is by volume changes due to the
movement of the boundary.
Dynamic
Working fluid is not confine within a boundary.
Energy transfer is by dynamic
effects of the rotor on the fluid stream.
Summary of Propeller and Rocket Thrust
For Aircraft propulsion the big advantage of using a propeller is that less fuel must be carried on board.
• The rate of airflow through the propeller can be as much as three orders of magnitude larger than the rate of fuel consumption of the driving engine.
Propulsion using a propeller has much better efficiency when compared to propulsion with a rocket.
• The aircraft using a propeller can travel much greater distances before having to refuel.
Comparison of the Axial-Flow and Radial-Flow Compressors
Axial-Flow compressors do not significantly change the direction of the flow stream, thus Axial-Flow Compressor allows for multiple stages. Radial-Flow Compressors can not be staged.
While the Radial-Flow Compressor has a larger Compressor Pressure Ratio (CPR) per stage, the multi-stages of the Axial-Flow compressor allows for a larger overall CPR.
The frontal area for a given air flow rate is smaller for an Axial-Flow Compressor than for a Radial-Flow Compressor.
The Axial-Flow Compressor has a higher efficiency.
Disadvantages are the higher cost to manufacture the Axial-Flow Compressor, and the Radial-flow Compressor is more durable than the Axial-Flow Compressor.